Class: String

Inherits:

Object

Object
String

show all

Includes:: Comparable

Defined in:: string.c

Overview

A String object holds and manipulates an arbitrary sequence of bytes, typically representing characters. String objects may be created using String::new or as literals.

Because of aliasing issues, users of strings should be aware of the methods that modify the contents of a String object. Typically, methods with names ending in “!” modify their receiver, while those without a “!” return a new String. However, there are exceptions, such as String#[]=.

Direct Known Subclasses

Warning::buffer

Class Method Summary collapse

.try_convert(object) ⇒ Object^?

If object is a String object, returns object.

Instance Method Summary collapse

#%(object) ⇒ Object

Returns the result of formatting object into the format specification self (see Kernel#sprintf for formatting details): “%05d” % 123 # => “00123”.
#*(integer) ⇒ Object

Returns a new String containing integer copies of self: “Ho! ” * 3 # => “Ho! Ho! Ho! ” “Ho! ” * 0 # => “”.
#+(other_string) ⇒ Object

Returns a new String containing other_string concatenated to self: “Hello from ” + self.to_s # => “Hello from main”.
#+ ⇒ self

Returns self if self is not frozen.
#- ⇒ Object

Returns a frozen, possibly pre-existing copy of the string.
#<<(object) ⇒ String

Returns a new String containing the concatenation of self and object: s = ‘foo’ s << ‘bar’ # => “foobar”.
#<=>(other_string) ⇒ -1, ...

Compares self and other_string, returning: - -1 if other_string is smaller.
#==(str2) ⇒ Object

Returns true if object has the same length and content; as self; false otherwise: s = ‘foo’ s == ‘foo’ # => true s == ‘food’ # => false s == ‘FOO’ # => false.
#===(str2) ⇒ Object

Returns true if object has the same length and content; as self; false otherwise: s = ‘foo’ s == ‘foo’ # => true s == ‘food’ # => false s == ‘FOO’ # => false.
#=~(y) ⇒ Object

Returns the Integer index of the first substring that matches the given regexp, or nil if no match found: ‘foo’ =~ /f/ # => 0 ‘foo’ =~ /o/ # => 1 ‘foo’ =~ /x/ # => nil.
#[](*args) ⇒ Object

Returns the substring of self specified by the arguments.
#[]=(*args) ⇒ Object

Element Assignment—Replaces some or all of the content of str.
#ascii_only? ⇒ Boolean

Returns true for a string which has only ASCII characters.
#b ⇒ String

Returns a copied string whose encoding is ASCII-8BIT.
#bytes ⇒ Array

Returns an array of bytes in str.
#bytesize ⇒ Integer

Returns the count of bytes in self: “x80u3042”.bytesize # => 4 “hello”.bytesize # => 5.
#byteslice(*args) ⇒ Object

Byte Reference—If passed a single Integer, returns a substring of one byte at that position.
#capitalize(*args) ⇒ Object

Returns a copy of str with the first character converted to uppercase and the remainder to lowercase.
#capitalize!(*args) ⇒ Object

Modifies str by converting the first character to uppercase and the remainder to lowercase.
#casecmp(other_str) ⇒ -1, ...

Compares self and other_string, ignoring case, and returning: - -1 if other_string is smaller.
#casecmp?(other_string) ⇒ true, ...

Returns true if self and other_string are equal after Unicode case folding, otherwise false: ‘foo’.casecmp?(‘foo’) # => true ‘foo’.casecmp?(‘food’) # => false ‘food’.casecmp?(‘foo’) # => true ‘FOO’.casecmp?(‘foo’) # => true ‘foo’.casecmp?(‘FOO’) # => true.
#center(width, padstr = ' ') ⇒ String

Centers str in width.
#chars ⇒ Array

Returns an array of characters in str.
#chomp(separator = $/) ⇒ String

Returns a new String with the given record separator removed from the end of str (if present).
#chomp!(separator = $/) ⇒ String^?

Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.
#chop ⇒ String

Returns a new String with the last character removed.
#chop! ⇒ String^?

Processes str as for String#chop, returning str, or nil if str is the empty string.
#chr ⇒ String

Returns a one-character string at the beginning of the string.
#clear ⇒ String

Makes string empty.
#codepoints ⇒ Array

Returns an array of the Integer ordinals of the characters in str.
#concat(*objects) ⇒ Object

Returns a new String containing the concatenation of self and all objects in objects:.
#count([other_str]) ⇒ Integer

Each other_str parameter defines a set of characters to count.
#crypt(salt_str) ⇒ String

Returns the string generated by calling crypt(3) standard library function with str and salt_str, in this order, as its arguments.
#delete([other_str]) ⇒ String

Returns a copy of str with all characters in the intersection of its arguments deleted.
#delete!([other_str]) ⇒ String^?

Performs a delete operation in place, returning str, or nil if str was not modified.
#delete_prefix(prefix) ⇒ String

Returns a copy of str with leading prefix deleted.
#delete_prefix!(prefix) ⇒ self^?

Deletes leading prefix from str, returning nil if no change was made.
#delete_suffix(suffix) ⇒ String

Returns a copy of str with trailing suffix deleted.
#delete_suffix!(suffix) ⇒ self^?

Deletes trailing suffix from str, returning nil if no change was made.
#downcase(*args) ⇒ Object

Returns a copy of str with all uppercase letters replaced with their lowercase counterparts.
#downcase!(*args) ⇒ Object

Downcases the contents of str, returning nil if no changes were made.
#dump ⇒ String

Returns a quoted version of the string with all non-printing characters replaced by \xHH notation and all special characters escaped.
#each_byte ⇒ Object

Passes each byte in str to the given block, or returns an enumerator if no block is given.
#each_char ⇒ Object

Passes each character in str to the given block, or returns an enumerator if no block is given.
#each_codepoint ⇒ Object

Passes the Integer ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block.
#each_grapheme_cluster ⇒ Object

Passes each grapheme cluster in str to the given block, or returns an enumerator if no block is given.
#each_line(*args) ⇒ Object

Splits str using the supplied parameter as the record separator ($/ by default), passing each substring in turn to the supplied block.
#empty? ⇒ Boolean

Returns true if the length of self is zero, false otherwise: “hello”.empty? # => false “ ”.empty? # => false “”.empty? # => true.
#encode(*args) ⇒ Object

The first form returns a copy of str transcoded to encoding encoding.
#encode!(*args) ⇒ Object

The first form transcodes the contents of str from str.encoding to encoding.
#encoding ⇒ Encoding

Returns the Encoding object that represents the encoding of obj.
#end_with?([suffixes]) ⇒ Boolean

Returns true if str ends with one of the suffixes given.
#eql?(object) ⇒ Boolean

Returns true if object has the same length and content; as self; false otherwise: s = ‘foo’ s.eql?(‘foo’) # => true s.eql?(‘food’) # => false s.eql?(‘FOO’) # => false.
#force_encoding(encoding) ⇒ String

Changes the encoding to encoding and returns self.
#freeze ⇒ Object
#getbyte(index) ⇒ 0 .. 255

returns the indexth byte as an integer.
#grapheme_clusters ⇒ Array

Returns an array of grapheme clusters in str.
#gsub(*args) ⇒ Object

Returns a copy of str with all occurrences of pattern substituted for the second argument.
#gsub!(*args) ⇒ Object

Performs the substitutions of String#gsub in place, returning str, or nil if no substitutions were performed.
#hash ⇒ Integer

Returns the integer hash value for self.
#hex ⇒ Integer

Treats leading characters from str as a string of hexadecimal digits (with an optional sign and an optional 0x) and returns the corresponding number.
#include?(other_str) ⇒ Boolean

Returns true if str contains the given string or character.
#index(*args) ⇒ Object

Returns the Integer index of the first occurrence of the given substring, or nil if none found: ‘foo’.index(‘f’) # => 0 ‘foo’.index(‘o’) # => 1 ‘foo’.index(‘oo’) # => 1 ‘foo’.index(‘ooo’) # => nil.
#initialize(*args) ⇒ Object constructor

Returns a new String that is a copy of string.
#replace(other_str) ⇒ String

Replaces the contents of str with the corresponding values in other_str.
#insert(index, other_string) ⇒ self

Inserts the given other_string into self; returns self.
#inspect ⇒ String

Returns a printable version of str, surrounded by quote marks, with special characters escaped.
#intern ⇒ Object

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist.
#length ⇒ Integer

Returns the count of characters (not bytes) in self: “x80u3042”.length # => 2 “hello”.length # => 5.
#lines(separator = $/, chomp: false) ⇒ Array

Returns an array of lines in str split using the supplied record separator ($/ by default).
#ljust(integer, padstr = ' ') ⇒ String

If integer is greater than the length of str, returns a new String of length integer with str left justified and padded with padstr; otherwise, returns str.
#lstrip ⇒ String

Returns a copy of the receiver with leading whitespace removed.
#lstrip! ⇒ self^?

Removes leading whitespace from the receiver.
#match(*args) ⇒ Object

Returns a Matchdata object (or nil) based on self and the given pattern.
#match?(pattern, offset = 0) ⇒ Boolean

Returns true or false based on whether a match is found for self and pattern.
#succ ⇒ String

Returns the successor to self.
#succ! ⇒ self

Equivalent to String#succ, but modifies self in place; returns self.
#oct ⇒ Integer

Treats leading characters of str as a string of octal digits (with an optional sign) and returns the corresponding number.
#ord ⇒ Integer

Returns the Integer ordinal of a one-character string.
#partition(sep) ⇒ Object

Searches sep or pattern (regexp) in the string and returns the part before it, the match, and the part after it.
#prepend(*other_strings) ⇒ String

Returns a new String containing the concatenation of all given other_strings and self: s = ‘foo’ s.prepend(‘bar’, ‘baz’) # => “barbazfoo”.
#replace(other_str) ⇒ String

Replaces the contents of str with the corresponding values in other_str.
#reverse ⇒ String

Returns a new string with the characters from str in reverse order.
#reverse! ⇒ String

Reverses str in place.
#rindex(*args) ⇒ Object

Returns the Integer index of the last occurrence of the given substring, or nil if none found: ‘foo’.rindex(‘f’) # => 0 ‘foo’.rindex(‘o’) # => 2 ‘foo’.rindex(‘oo’) # => 1 ‘foo’.rindex(‘ooo’) # => nil.
#rjust(integer, padstr = ' ') ⇒ String

If integer is greater than the length of str, returns a new String of length integer with str right justified and padded with padstr; otherwise, returns str.
#rpartition(sep) ⇒ Object

Searches sep or pattern (regexp) in the string from the end of the string, and returns the part before it, the match, and the part after it.
#rstrip ⇒ String

Returns a copy of the receiver with trailing whitespace removed.
#rstrip! ⇒ self^?

Removes trailing whitespace from the receiver.
#scan(pat) ⇒ Object

Both forms iterate through str, matching the pattern (which may be a Regexp or a String).
#scrub(*args) ⇒ Object

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self.
#scrub!(*args) ⇒ Object

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self.
#setbyte(index, integer) ⇒ Integer

modifies the indexth byte as integer.
#length ⇒ Integer

Returns the count of characters (not bytes) in self: “x80u3042”.length # => 2 “hello”.length # => 5.
#slice(*args) ⇒ Object

Returns the substring of self specified by the arguments.
#slice!(*args) ⇒ Object

Deletes the specified portion from str, and returns the portion deleted.
#split(*args) ⇒ Object

Divides str into substrings based on a delimiter, returning an array of these substrings.
#squeeze([other_str]) ⇒ String

Builds a set of characters from the other_str parameter(s) using the procedure described for String#count.
#squeeze!([other_str]) ⇒ String^?

Squeezes str in place, returning either str, or nil if no changes were made.
#start_with?([prefixes]) ⇒ Boolean

Returns true if str starts with one of the prefixes given.
#strip ⇒ String

Returns a copy of the receiver with leading and trailing whitespace removed.
#strip! ⇒ self^?

Removes leading and trailing whitespace from the receiver.
#sub(*args) ⇒ Object

Returns a copy of str with the first occurrence of pattern replaced by the second argument.
#sub!(*args) ⇒ Object

Performs the same substitution as String#sub in-place.
#succ ⇒ String

Returns the successor to self.
#succ! ⇒ self

Equivalent to String#succ, but modifies self in place; returns self.
#sum(n = 16) ⇒ Integer

Returns a basic n-bit checksum of the characters in str, where n is the optional Integer parameter, defaulting to 16.
#swapcase(*args) ⇒ Object

Returns a copy of str with uppercase alphabetic characters converted to lowercase and lowercase characters converted to uppercase.
#swapcase!(*args) ⇒ Object

Equivalent to String#swapcase, but modifies the receiver in place, returning str, or nil if no changes were made.
#to_c ⇒ Object

Returns a complex which denotes the string form.
#to_f ⇒ Float

Returns the result of interpreting leading characters in str as a floating point number.
#to_i(base = 10) ⇒ Integer

Returns the result of interpreting leading characters in str as an integer base base (between 2 and 36).
#to_r ⇒ Object

Returns the result of interpreting leading characters in str as a rational.
#to_s ⇒ Object

Returns self.
#to_str ⇒ Object

Returns self.
#to_sym ⇒ Object

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist.
#tr(from_str, to_str) ⇒ String

Returns a copy of str with the characters in from_str replaced by the corresponding characters in to_str.
#tr!(from_str, to_str) ⇒ String^?

Translates str in place, using the same rules as String#tr.
#tr_s(from_str, to_str) ⇒ String

Processes a copy of str as described under String#tr, then removes duplicate characters in regions that were affected by the translation.
#tr_s!(from_str, to_str) ⇒ String^?

Performs String#tr_s processing on str in place, returning str, or nil if no changes were made.
#undump ⇒ String

Returns an unescaped version of the string.
#unicode_normalize(form = :nfc) ⇒ Object

Unicode Normalization—Returns a normalized form of str, using Unicode normalizations NFC, NFD, NFKC, or NFKD.
#unicode_normalize!(form = :nfc) ⇒ Object

Destructive version of String#unicode_normalize, doing Unicode normalization in place.
#unicode_normalized?(form = :nfc) ⇒ Boolean

Checks whether str is in Unicode normalization form form, which can be any of the four values :nfc, :nfd, :nfkc, or :nfkd.
#upcase(*args) ⇒ Object

Returns a copy of str with all lowercase letters replaced with their uppercase counterparts.
#upcase!(*args) ⇒ Object

Upcases the contents of str, returning nil if no changes were made.
#upto(*args) ⇒ Object

With a block given, calls the block with each String value returned by successive calls to String#succ; the first value is self, the next is self.succ, and so on; the sequence terminates when value other_string is reached; returns self: ‘a8’.upto(‘b6’) {|s| print s, ‘ ’ } # => “a8” Output: a8 a9 b0 b1 b2 b3 b4 b5 b6.
#valid_encoding? ⇒ Boolean

Returns true for a string which is encoded correctly.

Methods included from Comparable

#<, #<=, #>, #>=, #between?, #clamp

Constructor Details

#new(string = '') ⇒ `Object` #new(string = '', encoding: encoding) ⇒ `Object` #new(string = '', capacity: size) ⇒ `Object`

Returns a new String that is a copy of string.

With no arguments, returns the empty string with the Encoding ASCII-8BIT:

s = String.new
s # => ""
s.encoding # => #<Encoding:ASCII-8BIT>

With the single String argument string, returns a copy of string with the same encoding as string:

s = String.new("Que veut dire \u{e7}a?")
s # => "Que veut dire \u{e7}a?"
s.encoding # => #<Encoding:UTF-8>

Literal strings like "" or here-documents always use script encoding, unlike String.new.

With keyword encoding, returns a copy of str with the specified encoding:

s = String.new(encoding: 'ASCII')
s.encoding # => #<Encoding:US-ASCII>
s = String.new('foo', encoding: 'ASCII')
s.encoding # => #<Encoding:US-ASCII>

Note that these are equivalent:

s0 = String.new('foo', encoding: 'ASCII')
s1 = 'foo'.force_encoding('ASCII')
s0.encoding == s1.encoding # => true

With keyword capacity, returns a copy of str; the given capacity may set the size of the internal buffer, which may affect performance:

String.new(capacity: 1) # => ""
String.new(capacity: 4096) # => ""

The string, encoding, and capacity arguments may all be used together:

String.new('hello', encoding: 'UTF-8', capacity: 25)

# File 'string.c', line 1669

static VALUE
rb_str_init(int argc, VALUE *argv, VALUE str)
{
    static ID keyword_ids[2];
    VALUE orig, opt, venc, vcapa;
    VALUE kwargs[2];
    rb_encoding *enc = 0;
    int n;

    if (!keyword_ids[0]) {
	keyword_ids[0] = rb_id_encoding();
	CONST_ID(keyword_ids[1], "capacity");
    }

    n = rb_scan_args(argc, argv, "01:", &orig, &opt);
    if (!NIL_P(opt)) {
	rb_get_kwargs(opt, keyword_ids, 0, 2, kwargs);
	venc = kwargs[0];
	vcapa = kwargs[1];
	if (venc != Qundef && !NIL_P(venc)) {
	    enc = rb_to_encoding(venc);
	}
	if (vcapa != Qundef && !NIL_P(vcapa)) {
	    long capa = NUM2LONG(vcapa);
	    long len = 0;
	    int termlen = enc ? rb_enc_mbminlen(enc) : 1;

	    if (capa < STR_BUF_MIN_SIZE) {
		capa = STR_BUF_MIN_SIZE;
	    }
	    if (n == 1) {
		StringValue(orig);
		len = RSTRING_LEN(orig);
		if (capa < len) {
		    capa = len;
		}
		if (orig == str) n = 0;
	    }
	    str_modifiable(str);
	    if (STR_EMBED_P(str)) { /* make noembed always */
                char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
                memcpy(new_ptr, RSTRING(str)->as.ary, RSTRING_EMBED_LEN_MAX + 1);
                RSTRING(str)->as.heap.ptr = new_ptr;
            }
            else if (FL_TEST(str, STR_SHARED|STR_NOFREE)) {
                const size_t size = (size_t)capa + termlen;
                const char *const old_ptr = RSTRING_PTR(str);
                const size_t osize = RSTRING(str)->as.heap.len + TERM_LEN(str);
                char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
                memcpy(new_ptr, old_ptr, osize < size ? osize : size);
                FL_UNSET_RAW(str, STR_SHARED);
                RSTRING(str)->as.heap.ptr = new_ptr;
	    }
	    else if (STR_HEAP_SIZE(str) != (size_t)capa + termlen) {
		SIZED_REALLOC_N(RSTRING(str)->as.heap.ptr, char,
			(size_t)capa + termlen, STR_HEAP_SIZE(str));
	    }
	    RSTRING(str)->as.heap.len = len;
	    TERM_FILL(&RSTRING(str)->as.heap.ptr[len], termlen);
	    if (n == 1) {
		memcpy(RSTRING(str)->as.heap.ptr, RSTRING_PTR(orig), len);
		rb_enc_cr_str_exact_copy(str, orig);
	    }
	    FL_SET(str, STR_NOEMBED);
	    RSTRING(str)->as.heap.aux.capa = capa;
	}
	else if (n == 1) {
	    rb_str_replace(str, orig);
	}
	if (enc) {
	    rb_enc_associate(str, enc);
	    ENC_CODERANGE_CLEAR(str);
	}
    }
    else if (n == 1) {
	rb_str_replace(str, orig);
    }
    return str;
}

Class Method Details

.try_convert(object) ⇒ `Object`^?

If object is a String object, returns object.

Otherwise if object responds to :to_str, calls object.to_str and returns the result.

Returns nil if object does not respond to :to_str

Raises an exception unless object.to_str returns a String object.

Returns:

(Object, nil)

# File 'string.c', line 2456

static VALUE
rb_str_s_try_convert(VALUE dummy, VALUE str)
{
    return rb_check_string_type(str);
}

Instance Method Details

#%(object) ⇒ `Object`

Returns the result of formatting object into the format specification self (see Kernel#sprintf for formatting details):

"%05d" % 123 # => "00123"

If self contains multiple substitutions, object must be an Array or Hash containing the values to be substituted:

"%-5s: %016x" % [ "ID", self.object_id ] # => "ID   : 00002b054ec93168"
"foo = %{foo}" % {foo: 'bar'} # => "foo = bar"
"foo = %{foo}, baz = %{baz}" % {foo: 'bar', baz: 'bat'} # => "foo = bar, baz = bat"

# File 'string.c', line 2158

static VALUE
rb_str_format_m(VALUE str, VALUE arg)
{
    VALUE tmp = rb_check_array_type(arg);

    if (!NIL_P(tmp)) {
        return rb_str_format(RARRAY_LENINT(tmp), RARRAY_CONST_PTR(tmp), str);
    }
    return rb_str_format(1, &arg, str);
}

#*(integer) ⇒ `Object`

Returns a new String containing integer copies of self:

"Ho! " * 3 # => "Ho! Ho! Ho! "
"Ho! " * 0 # => ""

# File 'string.c', line 2088

VALUE
rb_str_times(VALUE str, VALUE times)
{
    VALUE str2;
    long n, len;
    char *ptr2;
    int termlen;

    if (times == INT2FIX(1)) {
        return str_duplicate(rb_cString, str);
    }
    if (times == INT2FIX(0)) {
        str2 = str_alloc(rb_cString);
	rb_enc_copy(str2, str);
	return str2;
    }
    len = NUM2LONG(times);
    if (len < 0) {
	rb_raise(rb_eArgError, "negative argument");
    }
    if (RSTRING_LEN(str) == 1 && RSTRING_PTR(str)[0] == 0) {
       str2 = str_alloc(rb_cString);
       if (!STR_EMBEDDABLE_P(len, 1)) {
           RSTRING(str2)->as.heap.aux.capa = len;
           RSTRING(str2)->as.heap.ptr = ZALLOC_N(char, (size_t)len + 1);
           STR_SET_NOEMBED(str2);
       }
       STR_SET_LEN(str2, len);
       rb_enc_copy(str2, str);
       return str2;
    }
    if (len && LONG_MAX/len <  RSTRING_LEN(str)) {
	rb_raise(rb_eArgError, "argument too big");
    }

    len *= RSTRING_LEN(str);
    termlen = TERM_LEN(str);
    str2 = str_new0(rb_cString, 0, len, termlen);
    ptr2 = RSTRING_PTR(str2);
    if (len) {
        n = RSTRING_LEN(str);
        memcpy(ptr2, RSTRING_PTR(str), n);
        while (n <= len/2) {
            memcpy(ptr2 + n, ptr2, n);
            n *= 2;
        }
        memcpy(ptr2 + n, ptr2, len-n);
    }
    STR_SET_LEN(str2, len);
    TERM_FILL(&ptr2[len], termlen);
    rb_enc_cr_str_copy_for_substr(str2, str);

    return str2;
}

#+(other_string) ⇒ `Object`

Returns a new String containing other_string concatenated to self:

"Hello from " + self.to_s # => "Hello from main"

# File 'string.c', line 2018

VALUE
rb_str_plus(VALUE str1, VALUE str2)
{
    VALUE str3;
    rb_encoding *enc;
    char *ptr1, *ptr2, *ptr3;
    long len1, len2;
    int termlen;

    StringValue(str2);
    enc = rb_enc_check_str(str1, str2);
    RSTRING_GETMEM(str1, ptr1, len1);
    RSTRING_GETMEM(str2, ptr2, len2);
    termlen = rb_enc_mbminlen(enc);
    if (len1 > LONG_MAX - len2) {
	rb_raise(rb_eArgError, "string size too big");
    }
    str3 = str_new0(rb_cString, 0, len1+len2, termlen);
    ptr3 = RSTRING_PTR(str3);
    memcpy(ptr3, ptr1, len1);
    memcpy(ptr3+len1, ptr2, len2);
    TERM_FILL(&ptr3[len1+len2], termlen);

    ENCODING_CODERANGE_SET(str3, rb_enc_to_index(enc),
			   ENC_CODERANGE_AND(ENC_CODERANGE(str1), ENC_CODERANGE(str2)));
    RB_GC_GUARD(str1);
    RB_GC_GUARD(str2);
    return str3;
}

#+ ⇒ `self`

Returns self if self is not frozen.

Otherwise. returns self.dup, which is not frozen.

Returns:

(self)

# File 'string.c', line 2757

static VALUE
str_uplus(VALUE str)
{
    if (OBJ_FROZEN(str)) {
	return rb_str_dup(str);
    }
    else {
	return str;
    }
}

#- ⇒ `Object`

Returns a frozen, possibly pre-existing copy of the string.

The returned String will be deduplicated as long as it does not have any instance variables set on it.

# File 'string.c', line 2777

static VALUE
str_uminus(VALUE str)
{
    if (!BARE_STRING_P(str) && !rb_obj_frozen_p(str)) {
        str = rb_str_dup(str);
    }
    return rb_fstring(str);
}

#<<(object) ⇒ `String`

Returns a new String containing the concatenation of self and object:

s = 'foo'
s << 'bar' # => "foobar"

If object is an Integer, the value is considered a codepoint and converted to a character before concatenation:

s = 'foo'
s << 33 # => "foo!"

Related: String#concat, which takes multiple arguments.

Returns:

(String)

# File 'string.c', line 3190

VALUE
rb_str_concat(VALUE str1, VALUE str2)
{
    unsigned int code;
    rb_encoding *enc = STR_ENC_GET(str1);
    int encidx;

    if (RB_INTEGER_TYPE_P(str2)) {
	if (rb_num_to_uint(str2, &code) == 0) {
	}
	else if (FIXNUM_P(str2)) {
	    rb_raise(rb_eRangeError, "%ld out of char range", FIX2LONG(str2));
	}
	else {
	    rb_raise(rb_eRangeError, "bignum out of char range");
	}
    }
    else {
	return rb_str_append(str1, str2);
    }

    encidx = rb_enc_to_index(enc);
    if (encidx == ENCINDEX_ASCII || encidx == ENCINDEX_US_ASCII) {
	/* US-ASCII automatically extended to ASCII-8BIT */
	char buf[1];
	buf[0] = (char)code;
	if (code > 0xFF) {
	    rb_raise(rb_eRangeError, "%u out of char range", code);
	}
	rb_str_cat(str1, buf, 1);
	if (encidx == ENCINDEX_US_ASCII && code > 127) {
	    rb_enc_associate_index(str1, ENCINDEX_ASCII);
	    ENC_CODERANGE_SET(str1, ENC_CODERANGE_VALID);
	}
    }
    else {
	long pos = RSTRING_LEN(str1);
	int cr = ENC_CODERANGE(str1);
	int len;
	char *buf;

	switch (len = rb_enc_codelen(code, enc)) {
	  case ONIGERR_INVALID_CODE_POINT_VALUE:
	    rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
	    break;
	  case ONIGERR_TOO_BIG_WIDE_CHAR_VALUE:
	  case 0:
	    rb_raise(rb_eRangeError, "%u out of char range", code);
	    break;
	}
	buf = ALLOCA_N(char, len + 1);
	rb_enc_mbcput(code, buf, enc);
	if (rb_enc_precise_mbclen(buf, buf + len + 1, enc) != len) {
	    rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
	}
	rb_str_resize(str1, pos+len);
	memcpy(RSTRING_PTR(str1) + pos, buf, len);
	if (cr == ENC_CODERANGE_7BIT && code > 127)
	    cr = ENC_CODERANGE_VALID;
	ENC_CODERANGE_SET(str1, cr);
    }
    return str1;
}

#<=>(other_string) ⇒ `-1`, ...

Compares self and other_string, returning:

-1 if other_string is smaller.
0 if the two are equal.
1 if other_string is larger.
nil if the two are incomparable.

Examples:

'foo' <=> 'foo' # => 0
'foo' <=> 'food' # => -1
'food' <=> 'foo' # => 1
'FOO' <=> 'foo' # => -1
'foo' <=> 'FOO' # => 1
'foo' <=> 1 # => nil

Returns:

(-1, 0, 1, nil)

# File 'string.c', line 3451

static VALUE
rb_str_cmp_m(VALUE str1, VALUE str2)
{
    int result;
    VALUE s = rb_check_string_type(str2);
    if (NIL_P(s)) {
	return rb_invcmp(str1, str2);
    }
    result = rb_str_cmp(str1, s);
    return INT2FIX(result);
}

#==(object) ⇒ `Boolean` #===(object) ⇒ `Boolean`

Returns true if object has the same length and content; as self; false otherwise:

s = 'foo'
s == 'foo' # => true
s == 'food' # => false
s == 'FOO' # => false

Returns false if the two strings’ encodings are not compatible:

"\u{e4 f6 fc}".encode("ISO-8859-1") == ("\u{c4 d6 dc}") # => false

If object is not an instance of String but responds to to_str, then the two strings are compared using object.==.

Overloads:

#==(object) ⇒ Boolean
Returns:
- (Boolean)
#===(object) ⇒ Boolean
Returns:
- (Boolean)

# File 'string.c', line 3396

VALUE
rb_str_equal(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) {
	if (!rb_respond_to(str2, idTo_str)) {
	    return Qfalse;
	}
	return rb_equal(str2, str1);
    }
    return rb_str_eql_internal(str1, str2);
}

#==(object) ⇒ `Boolean` #===(object) ⇒ `Boolean`

Returns true if object has the same length and content; as self; false otherwise:

s = 'foo'
s == 'foo' # => true
s == 'food' # => false
s == 'FOO' # => false

Returns false if the two strings’ encodings are not compatible:

"\u{e4 f6 fc}".encode("ISO-8859-1") == ("\u{c4 d6 dc}") # => false

If object is not an instance of String but responds to to_str, then the two strings are compared using object.==.

Overloads:

#==(object) ⇒ Boolean
Returns:
- (Boolean)
#===(object) ⇒ Boolean
Returns:
- (Boolean)

# File 'string.c', line 3396

VALUE
rb_str_equal(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) {
	if (!rb_respond_to(str2, idTo_str)) {
	    return Qfalse;
	}
	return rb_equal(str2, str1);
    }
    return rb_str_eql_internal(str1, str2);
}

#=~(regexp) ⇒ `Integer`^? #=~(object) ⇒ `Integer`^?

Returns the Integer index of the first substring that matches the given regexp, or nil if no match found:

'foo' =~ /f/ # => 0
'foo' =~ /o/ # => 1
'foo' =~ /x/ # => nil

Note: also updates Regexp-related global variables.

If the given object is not a Regexp, returns the value returned by object =~ self.

Note that string =~ regexp is different from regexp =~ string (see Regexp#=~):

number= nil
"no. 9" =~ /(?<number>\d+)/
number # => nil (not assigned)
/(?<number>\d+)/ =~ "no. 9"
number #=> "9"

Overloads:

#=~(regexp) ⇒ Integer^?
Returns:
- (Integer, nil)
#=~(object) ⇒ Integer^?
Returns:
- (Integer, nil)

# File 'string.c', line 3936

static VALUE
rb_str_match(VALUE x, VALUE y)
{
    switch (OBJ_BUILTIN_TYPE(y)) {
      case T_STRING:
	rb_raise(rb_eTypeError, "type mismatch: String given");

      case T_REGEXP:
	return rb_reg_match(y, x);

      default:
	return rb_funcall(y, idEqTilde, 1, x);
    }
}

#[](index) ⇒ `nil` #[](start, length) ⇒ `nil` #[](range) ⇒ `nil` #[](regexp, capture = 0) ⇒ `nil` #[](substring) ⇒ `nil`

Returns the substring of self specified by the arguments.

When the single Integer argument index is given, returns the 1-character substring found in self at offset index:

'bar'[2] # => "r"

Counts backward from the end of self if index is negative:

'foo'[-3] # => "f"

Returns nil if index is out of range:

'foo'[3] # => nil
'foo'[-4] # => nil

When the two Integer arguments start and length are given, returns the substring of the given length found in self at offset start:

'foo'[0, 2] # => "fo"
'foo'[0, 0] # => ""

Counts backward from the end of self if start is negative:

'foo'[-2, 2] # => "oo"

Special case: returns a new empty String if start is equal to the length of self:

'foo'[3, 2] # => ""

Returns nil if start is out of range:

'foo'[4, 2] # => nil
'foo'[-4, 2] # => nil

Returns the trailing substring of self if length is large:

'foo'[1, 50] # => "oo"

Returns nil if length is negative:

'foo'[0, -1] # => nil

When the single Range argument range is given, derives start and length values from the given range, and returns values as above:

'foo'[0..1] is equivalent to 'foo'[0, 2].
'foo'[0...1] is equivalent to 'foo'[0, 1].

When the Regexp argument regexp is given, and the capture argument is 0, returns the first matching substring found in self, or nil if none found:

'foo'[/o/] # => "o"
'foo'[/x/] # => nil
s = 'hello there'
s[/[aeiou](.)\1/] # => "ell"
s[/[aeiou](.)\1/, 0] # => "ell"

If argument capture is given and not 0, it should be either an Integer capture group index or a String or Symbol capture group name; the method call returns only the specified capture (see Regexp Capturing):

s = 'hello there'
s[/[aeiou](.)\1/, 1] # => "l"
s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "non_vowel"] # => "l"
s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, :vowel] # => "e"

If an invalid capture group index is given, nil is returned. If an invalid capture group name is given, IndexError is raised.

When the single String argument substring is given, returns the substring from self if found, otherwise nil:

'foo'['oo'] # => "oo"
'foo'['xx'] # => nil

String#slice is an alias for String#[].

Overloads:

#[](index) ⇒ nil
Returns:
- (nil)
#[](start, length) ⇒ nil
Returns:
- (nil)
#[](range) ⇒ nil
Returns:
- (nil)
#[](regexp, capture = 0) ⇒ nil
Returns:
- (nil)
#[](substring) ⇒ nil
Returns:
- (nil)

# File 'string.c', line 4735

static VALUE
rb_str_aref_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
	if (RB_TYPE_P(argv[0], T_REGEXP)) {
	    return rb_str_subpat(str, argv[0], argv[1]);
	}
	else {
	    long beg = NUM2LONG(argv[0]);
	    long len = NUM2LONG(argv[1]);
	    return rb_str_substr(str, beg, len);
	}
    }
    rb_check_arity(argc, 1, 2);
    return rb_str_aref(str, argv[0]);
}

#[]=(integer) ⇒ `Object` #[]=(integer, integer) ⇒ `Object` #[]=(range) ⇒ `Object` #[]=(regexp) ⇒ `Object` #[]=(regexp, integer) ⇒ `Object` #[]=(regexp, name) ⇒ `Object` #[]=(other_str) ⇒ `Object`

Element Assignment—Replaces some or all of the content of str. The portion of the string affected is determined using the same criteria as String#[]. If the replacement string is not the same length as the text it is replacing, the string will be adjusted accordingly. If the regular expression or string is used as the index doesn’t match a position in the string, IndexError is raised. If the regular expression form is used, the optional second Integer allows you to specify which portion of the match to replace (effectively using the MatchData indexing rules. The forms that take an Integer will raise an IndexError if the value is out of range; the Range form will raise a RangeError, and the Regexp and String will raise an IndexError on negative match.

# File 'string.c', line 4960

static VALUE
rb_str_aset_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 3) {
	if (RB_TYPE_P(argv[0], T_REGEXP)) {
	    rb_str_subpat_set(str, argv[0], argv[1], argv[2]);
	}
	else {
	    rb_str_splice(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]), argv[2]);
	}
	return argv[2];
    }
    rb_check_arity(argc, 2, 3);
    return rb_str_aset(str, argv[0], argv[1]);
}

#ascii_only? ⇒ `Boolean`

Returns true for a string which has only ASCII characters.

"abc".force_encoding("UTF-8").ascii_only?          #=> true
"abc\u{6666}".force_encoding("UTF-8").ascii_only?  #=> false

Returns:

(Boolean)

# File 'string.c', line 10438

static VALUE
rb_str_is_ascii_only_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return cr == ENC_CODERANGE_7BIT ? Qtrue : Qfalse;
}

#b ⇒ `String`

Returns a copied string whose encoding is ASCII-8BIT.

Returns:

(String)

# File 'string.c', line 10400

static VALUE
rb_str_b(VALUE str)
{
    VALUE str2 = str_alloc(rb_cString);
    str_replace_shared_without_enc(str2, str);
    ENC_CODERANGE_CLEAR(str2);
    return str2;
}

#bytes ⇒ `Array`

Returns an array of bytes in str. This is a shorthand for str.each_byte.to_a.

If a block is given, which is a deprecated form, works the same as each_byte.

Returns:

(Array)

# File 'string.c', line 8692

static VALUE
rb_str_bytes(VALUE str)
{
    VALUE ary = WANTARRAY("bytes", RSTRING_LEN(str));
    return rb_str_enumerate_bytes(str, ary);
}

#bytesize ⇒ `Integer`

Returns the count of bytes in self:

"\x80\u3042".bytesize # => 4
"hello".bytesize # => 5

Related: String#length.

Returns:

(Integer)

# File 'string.c', line 1986

static VALUE
rb_str_bytesize(VALUE str)
{
    return LONG2NUM(RSTRING_LEN(str));
}

#byteslice(integer) ⇒ `String`^? #byteslice(integer, integer) ⇒ `String`^? #byteslice(range) ⇒ `String`^?

Byte Reference—If passed a single Integer, returns a substring of one byte at that position. If passed two Integer objects, returns a substring starting at the offset given by the first, and a length given by the second. If given a Range, a substring containing bytes at offsets given by the range is returned. In all three cases, if an offset is negative, it is counted from the end of str. Returns nil if the initial offset falls outside the string, the length is negative, or the beginning of the range is greater than the end. The encoding of the resulted string keeps original encoding.

"hello".byteslice(1)     #=> "e"
"hello".byteslice(-1)    #=> "o"
"hello".byteslice(1, 2)  #=> "el"
"\x80\u3042".byteslice(1, 3) #=> "\u3042"
"\x03\u3042\xff".byteslice(1..3) #=> "\u3042"

Overloads:

#byteslice(integer) ⇒ String^?
Returns:
- (String, nil)
#byteslice(integer, integer) ⇒ String^?
Returns:
- (String, nil)
#byteslice(range) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 5823

static VALUE
rb_str_byteslice(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
	long beg = NUM2LONG(argv[0]);
	long end = NUM2LONG(argv[1]);
	return str_byte_substr(str, beg, end, TRUE);
    }
    rb_check_arity(argc, 1, 2);
    return str_byte_aref(str, argv[0]);
}

#capitalize ⇒ `String` #capitalize([options]) ⇒ `String`

Returns a copy of str with the first character converted to uppercase and the remainder to lowercase.

See String#downcase for meaning of options and use with different encodings.

"hello".capitalize    #=> "Hello"
"HELLO".capitalize    #=> "Hello"
"123ABC".capitalize   #=> "123abc"

Overloads:

#capitalize ⇒ String
Returns:
- (String)
#capitalize([options]) ⇒ String
Returns:
- (String)

# File 'string.c', line 7127

static VALUE
rb_str_capitalize(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_TITLECASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return str;
    if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }
    return ret;
}

#capitalize! ⇒ `String`^? #capitalize!([options]) ⇒ `String`^?

Modifies str by converting the first character to uppercase and the remainder to lowercase. Returns nil if no changes are made. There is an exception for modern Georgian (mkhedruli/MTAVRULI), where the result is the same as for String#downcase, to avoid mixed case.

See String#downcase for meaning of options and use with different encodings.

a = "hello"
a.capitalize!   #=> "Hello"
a               #=> "Hello"
a.capitalize!   #=> nil

Overloads:

#capitalize! ⇒ String^?
Returns:
- (String, nil)
#capitalize!([options]) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 7092

static VALUE
rb_str_capitalize_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_TITLECASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
	str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#casecmp(other_str) ⇒ `-1`, ...

Compares self and other_string, ignoring case, and returning:

-1 if other_string is smaller.
0 if the two are equal.
1 if other_string is larger.
nil if the two are incomparable.

Examples:

'foo'.casecmp('foo') # => 0
'foo'.casecmp('food') # => -1
'food'.casecmp('foo') # => 1
'FOO'.casecmp('foo') # => 0
'foo'.casecmp('FOO') # => 0
'foo'.casecmp(1) # => nil

Returns:

(-1, 0, 1, nil)

# File 'string.c', line 3485

static VALUE
rb_str_casecmp(VALUE str1, VALUE str2)
{
    VALUE s = rb_check_string_type(str2);
    if (NIL_P(s)) {
	return Qnil;
    }
    return str_casecmp(str1, s);
}

#casecmp?(other_string) ⇒ `true`, ...

Returns true if self and other_string are equal after Unicode case folding, otherwise false:

'foo'.casecmp?('foo') # => true
'foo'.casecmp?('food') # => false
'food'.casecmp?('foo') # => true
'FOO'.casecmp?('foo') # => true
'foo'.casecmp?('FOO') # => true

Returns nil if the two values are incomparable:

'foo'.casecmp?(1) # => nil

Returns:

(true, false, nil)

# File 'string.c', line 3568

static VALUE
rb_str_casecmp_p(VALUE str1, VALUE str2)
{
    VALUE s = rb_check_string_type(str2);
    if (NIL_P(s)) {
	return Qnil;
    }
    return str_casecmp_p(str1, s);
}

#center(width, padstr = ' ') ⇒ `String`

Centers str in width. If width is greater than the length of str, returns a new String of length width with str centered and padded with padstr; otherwise, returns str.

"hello".center(4)         #=> "hello"
"hello".center(20)        #=> "       hello        "
"hello".center(20, '123') #=> "1231231hello12312312"

Returns:

(String)

# File 'string.c', line 10020

static VALUE
rb_str_center(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'c');
}

#chars ⇒ `Array`

Returns an array of characters in str. This is a shorthand for str.each_char.to_a.

If a block is given, which is a deprecated form, works the same as each_char.

Returns:

(Array)

# File 'string.c', line 8770

static VALUE
rb_str_chars(VALUE str)
{
    VALUE ary = WANTARRAY("chars", rb_str_strlen(str));
    return rb_str_enumerate_chars(str, ary);
}

#chomp(separator = $/) ⇒ `String`

Returns a new String with the given record separator removed from the end of str (if present). If $/ has not been changed from the default Ruby record separator, then chomp also removes carriage return characters (that is it will remove \n, \r, and \r\n). If $/ is an empty string, it will remove all trailing newlines from the string.

"hello".chomp                #=> "hello"
"hello\n".chomp              #=> "hello"
"hello\r\n".chomp            #=> "hello"
"hello\n\r".chomp            #=> "hello\n"
"hello\r".chomp              #=> "hello"
"hello \n there".chomp       #=> "hello \n there"
"hello".chomp("llo")         #=> "he"
"hello\r\n\r\n".chomp('')    #=> "hello"
"hello\r\n\r\r\n".chomp('')  #=> "hello\r\n\r"

Returns:

(String)

# File 'string.c', line 9251

static VALUE
rb_str_chomp(int argc, VALUE *argv, VALUE str)
{
    VALUE rs = chomp_rs(argc, argv);
    if (NIL_P(rs)) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, 0, chompped_length(str, rs));
}

#chomp!(separator = $/) ⇒ `String`^?

Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.

Returns:

(String, nil)

# File 'string.c', line 9217

static VALUE
rb_str_chomp_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE rs;
    str_modifiable(str);
    if (RSTRING_LEN(str) == 0) return Qnil;
    rs = chomp_rs(argc, argv);
    if (NIL_P(rs)) return Qnil;
    return rb_str_chomp_string(str, rs);
}

#chop ⇒ `String`

Returns a new String with the last character removed. If the string ends with \r\n, both characters are removed. Applying chop to an empty string returns an empty string. String#chomp is often a safer alternative, as it leaves the string unchanged if it doesn’t end in a record separator.

"string\r\n".chop   #=> "string"
"string\n\r".chop   #=> "string\n"
"string\n".chop     #=> "string"
"string".chop       #=> "strin"
"x".chop.chop       #=> ""

Returns:

(String)

# File 'string.c', line 9064

static VALUE
rb_str_chop(VALUE str)
{
    return rb_str_subseq(str, 0, chopped_length(str));
}

#chop! ⇒ `String`^?

Processes str as for String#chop, returning str, or nil if str is the empty string. See also String#chomp!.

Returns:

(String, nil)

# File 'string.c', line 9028

static VALUE
rb_str_chop_bang(VALUE str)
{
    str_modify_keep_cr(str);
    if (RSTRING_LEN(str) > 0) {
	long len;
	len = chopped_length(str);
	STR_SET_LEN(str, len);
	TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
	if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
	    ENC_CODERANGE_CLEAR(str);
	}
	return str;
    }
    return Qnil;
}

#chr ⇒ `String`

Returns a one-character string at the beginning of the string.

a = "abcde"
a.chr    #=> "a"

Returns:

(String)

# File 'string.c', line 5634

static VALUE
rb_str_chr(VALUE str)
{
    return rb_str_substr(str, 0, 1);
}

#clear ⇒ `String`

Makes string empty.

a = "abcde"
a.clear    #=> ""

Returns:

(String)

# File 'string.c', line 5610

static VALUE
rb_str_clear(VALUE str)
{
    str_discard(str);
    STR_SET_EMBED(str);
    STR_SET_EMBED_LEN(str, 0);
    RSTRING_PTR(str)[0] = 0;
    if (rb_enc_asciicompat(STR_ENC_GET(str)))
	ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
    else
	ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
    return str;
}

#codepoints ⇒ `Array`

Returns an array of the Integer ordinals of the characters in str. This is a shorthand for str.each_codepoint.to_a.

If a block is given, which is a deprecated form, works the same as each_codepoint.

Returns:

(Array)

# File 'string.c', line 8845

static VALUE
rb_str_codepoints(VALUE str)
{
    VALUE ary = WANTARRAY("codepoints", rb_str_strlen(str));
    return rb_str_enumerate_codepoints(str, ary);
}

#concat(*objects) ⇒ `Object`

Returns a new String containing the concatenation of self and all objects in objects:

s = 'foo'
s.concat('bar', 'baz') # => "foobarbaz"

For each given object object that is an Integer, the value is considered a codepoint and converted to a character before concatenation:

s = 'foo'
s.concat(32, 'bar', 32, 'baz') # => "foo bar baz"

Related: String#<<, which takes a single argument.

# File 'string.c', line 3153

static VALUE
rb_str_concat_multi(int argc, VALUE *argv, VALUE str)
{
    str_modifiable(str);

    if (argc == 1) {
	return rb_str_concat(str, argv[0]);
    }
    else if (argc > 1) {
	int i;
	VALUE arg_str = rb_str_tmp_new(0);
	rb_enc_copy(arg_str, str);
	for (i = 0; i < argc; i++) {
	    rb_str_concat(arg_str, argv[i]);
	}
	rb_str_buf_append(str, arg_str);
    }

    return str;
}

#count([other_str]) ⇒ `Integer`

Each other_str parameter defines a set of characters to count. The intersection of these sets defines the characters to count in str. Any other_str that starts with a caret ^ is negated. The sequence c1-c2 means all characters between c1 and c2. The backslash character \ can be used to escape ^ or - and is otherwise ignored unless it appears at the end of a sequence or the end of a other_str.

a = "hello world"
a.count "lo"                   #=> 5
a.count "lo", "o"              #=> 2
a.count "hello", "^l"          #=> 4
a.count "ej-m"                 #=> 4

"hello^world".count "\\^aeiou" #=> 4
"hello-world".count "a\\-eo"   #=> 4

c = "hello world\\r\\n"
c.count "\\"                   #=> 2
c.count "\\A"                  #=> 0
c.count "X-\\w"                #=> 3

Returns:

(Integer)

# File 'string.c', line 7936

static VALUE
rb_str_count(int argc, VALUE *argv, VALUE str)
{
    char table[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0, tstr;
    char *s, *send;
    int i;
    int ascompat;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);

    tstr = argv[0];
    StringValue(tstr);
    enc = rb_enc_check(str, tstr);
    if (argc == 1) {
	const char *ptstr;
	if (RSTRING_LEN(tstr) == 1 && rb_enc_asciicompat(enc) &&
	    (ptstr = RSTRING_PTR(tstr),
	     ONIGENC_IS_ALLOWED_REVERSE_MATCH(enc, (const unsigned char *)ptstr, (const unsigned char *)ptstr+1)) &&
	    !is_broken_string(str)) {
	    int n = 0;
	    int clen;
	    unsigned char c = rb_enc_codepoint_len(ptstr, ptstr+1, &clen, enc);

	    s = RSTRING_PTR(str);
	    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
	    send = RSTRING_END(str);
	    while (s < send) {
		if (*(unsigned char*)s++ == c) n++;
	    }
	    return INT2NUM(n);
	}
    }

    tr_setup_table(tstr, table, TRUE, &del, &nodel, enc);
    for (i=1; i<argc; i++) {
	tstr = argv[i];
	StringValue(tstr);
	enc = rb_enc_check(str, tstr);
	tr_setup_table(tstr, table, FALSE, &del, &nodel, enc);
    }

    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
    send = RSTRING_END(str);
    ascompat = rb_enc_asciicompat(enc);
    i = 0;
    while (s < send) {
	unsigned int c;

	if (ascompat && (c = *(unsigned char*)s) < 0x80) {
	    if (table[c]) {
		i++;
	    }
	    s++;
	}
	else {
	    int clen;
	    c = rb_enc_codepoint_len(s, send, &clen, enc);
	    if (tr_find(c, table, del, nodel)) {
		i++;
	    }
	    s += clen;
	}
    }

    return INT2NUM(i);
}

#crypt(salt_str) ⇒ `String`

Returns the string generated by calling crypt(3) standard library function with str and salt_str, in this order, as its arguments. Please do not use this method any longer. It is legacy; provided only for backward compatibility with ruby scripts in earlier days. It is bad to use in contemporary programs for several reasons:

Behaviour of C’s crypt(3) depends on the OS it is run. The generated string lacks data portability.
On some OSes such as Mac OS, crypt(3) never fails (i.e. silently ends up in unexpected results).
On some OSes such as Mac OS, crypt(3) is not thread safe.
So-called “traditional” usage of crypt(3) is very very very weak. According to its manpage, Linux’s traditional crypt(3) output has only 2**56 variations; too easy to brute force today. And this is the default behaviour.
In order to make things robust some OSes implement so-called “modular” usage. To go through, you have to do a complex build-up of the salt_str parameter, by hand. Failure in generation of a proper salt string tends not to yield any errors; typos in parameters are normally not detectable.
- For instance, in the following example, the second invocation of String#crypt is wrong; it has a typo in “round=” (lacks “s”). However the call does not fail and something unexpected is generated.
```
"foo".crypt("$5$rounds=1000$salt$") # OK, proper usage
"foo".crypt("$5$round=1000$salt$")  # Typo not detected
```
Even in the “modular” mode, some hash functions are considered archaic and no longer recommended at all; for instance module $1$ is officially abandoned by its author: see phk.freebsd.dk/sagas/md5crypt_eol.html . For another instance module $3$ is considered completely broken: see the manpage of FreeBSD.
On some OS such as Mac OS, there is no modular mode. Yet, as written above, crypt(3) on Mac OS never fails. This means even if you build up a proper salt string it generates a traditional DES hash anyways, and there is no way for you to be aware of.
```
"foo".crypt("$5$rounds=1000$salt$") # => "$5fNPQMxC5j6."
```

If for some reason you cannot migrate to other secure contemporary password hashing algorithms, install the string-crypt gem and require 'string/crypt' to continue using it.

Returns:

(String)

# File 'string.c', line 9733

static VALUE
rb_str_crypt(VALUE str, VALUE salt)
{
#ifdef HAVE_CRYPT_R
    VALUE databuf;
    struct crypt_data *data;
#   define CRYPT_END() ALLOCV_END(databuf)
#else
    extern char *crypt(const char *, const char *);
#   define CRYPT_END() (void)0
#endif
    VALUE result;
    const char *s, *saltp;
    char *res;
#ifdef BROKEN_CRYPT
    char salt_8bit_clean[3];
#endif

    StringValue(salt);
    mustnot_wchar(str);
    mustnot_wchar(salt);
    if (RSTRING_LEN(salt) < 2) {
        goto short_salt;
    }

    s = StringValueCStr(str);
    saltp = RSTRING_PTR(salt);
    if (!saltp[0] || !saltp[1]) goto short_salt;
#ifdef BROKEN_CRYPT
    if (!ISASCII((unsigned char)saltp[0]) || !ISASCII((unsigned char)saltp[1])) {
	salt_8bit_clean[0] = saltp[0] & 0x7f;
	salt_8bit_clean[1] = saltp[1] & 0x7f;
	salt_8bit_clean[2] = '\0';
	saltp = salt_8bit_clean;
    }
#endif
#ifdef HAVE_CRYPT_R
    data = ALLOCV(databuf, sizeof(struct crypt_data));
# ifdef HAVE_STRUCT_CRYPT_DATA_INITIALIZED
    data->initialized = 0;
# endif
    res = crypt_r(s, saltp, data);
#else
    res = crypt(s, saltp);
#endif
    if (!res) {
	int err = errno;
	CRYPT_END();
	rb_syserr_fail(err, "crypt");
    }
    result = rb_str_new_cstr(res);
    CRYPT_END();
    return result;

  short_salt:
    rb_raise(rb_eArgError, "salt too short (need >=2 bytes)");
    UNREACHABLE_RETURN(Qundef);
}

#delete([other_str]) ⇒ `String`

Returns a copy of str with all characters in the intersection of its arguments deleted. Uses the same rules for building the set of characters as String#count.

"hello".delete "l","lo"        #=> "heo"
"hello".delete "lo"            #=> "he"
"hello".delete "aeiou", "^e"   #=> "hell"
"hello".delete "ej-m"          #=> "ho"

Returns:

(String)

# File 'string.c', line 7755

static VALUE
rb_str_delete(int argc, VALUE *argv, VALUE str)
{
    str = str_duplicate(rb_cString, str);
    rb_str_delete_bang(argc, argv, str);
    return str;
}

#delete!([other_str]) ⇒ `String`^?

Performs a delete operation in place, returning str, or nil if str was not modified.

Returns:

(String, nil)

# File 'string.c', line 7679

static VALUE
rb_str_delete_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    char *s, *send, *t;
    VALUE del = 0, nodel = 0;
    int modify = 0;
    int i, ascompat, cr;

    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i=0; i<argc; i++) {
	VALUE s = argv[i];

	StringValue(s);
	enc = rb_enc_check(str, s);
	tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
    }

    str_modify_keep_cr(str);
    ascompat = rb_enc_asciicompat(enc);
    s = t = RSTRING_PTR(str);
    send = RSTRING_END(str);
    cr = ascompat ? ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
    while (s < send) {
	unsigned int c;
	int clen;

	if (ascompat && (c = *(unsigned char*)s) < 0x80) {
	    if (squeez[c]) {
		modify = 1;
	    }
	    else {
		if (t != s) *t = c;
		t++;
	    }
	    s++;
	}
	else {
	    c = rb_enc_codepoint_len(s, send, &clen, enc);

	    if (tr_find(c, squeez, del, nodel)) {
		modify = 1;
	    }
	    else {
		if (t != s) rb_enc_mbcput(c, t, enc);
		t += clen;
		if (cr == ENC_CODERANGE_7BIT) cr = ENC_CODERANGE_VALID;
	    }
	    s += clen;
	}
    }
    TERM_FILL(t, TERM_LEN(str));
    STR_SET_LEN(str, t - RSTRING_PTR(str));
    ENC_CODERANGE_SET(str, cr);

    if (modify) return str;
    return Qnil;
}

#delete_prefix(prefix) ⇒ `String`

Returns a copy of str with leading prefix deleted.

"hello".delete_prefix("hel") #=> "lo"
"hello".delete_prefix("llo") #=> "hello"

Returns:

(String)

# File 'string.c', line 10255

static VALUE
rb_str_delete_prefix(VALUE str, VALUE prefix)
{
    long prefixlen;

    prefixlen = deleted_prefix_length(str, prefix);
    if (prefixlen <= 0) return str_duplicate(rb_cString, str);

    return rb_str_subseq(str, prefixlen, RSTRING_LEN(str) - prefixlen);
}

#delete_prefix!(prefix) ⇒ `self`^?

Deletes leading prefix from str, returning nil if no change was made.

"hello".delete_prefix!("hel") #=> "lo"
"hello".delete_prefix!("llo") #=> nil

Returns:

(self, nil)

# File 'string.c', line 10233

static VALUE
rb_str_delete_prefix_bang(VALUE str, VALUE prefix)
{
    long prefixlen;
    str_modify_keep_cr(str);

    prefixlen = deleted_prefix_length(str, prefix);
    if (prefixlen <= 0) return Qnil;

    return rb_str_drop_bytes(str, prefixlen);
}

#delete_suffix(suffix) ⇒ `String`

Returns a copy of str with trailing suffix deleted.

"hello".delete_suffix("llo") #=> "he"
"hello".delete_suffix("hel") #=> "hello"

Returns:

(String)

# File 'string.c', line 10341

static VALUE
rb_str_delete_suffix(VALUE str, VALUE suffix)
{
    long suffixlen;

    suffixlen = deleted_suffix_length(str, suffix);
    if (suffixlen <= 0) return str_duplicate(rb_cString, str);

    return rb_str_subseq(str, 0, RSTRING_LEN(str) - suffixlen);
}

#delete_suffix!(suffix) ⇒ `self`^?

Deletes trailing suffix from str, returning nil if no change was made.

"hello".delete_suffix!("llo") #=> "he"
"hello".delete_suffix!("hel") #=> nil

Returns:

(self, nil)

# File 'string.c', line 10311

static VALUE
rb_str_delete_suffix_bang(VALUE str, VALUE suffix)
{
    long olen, suffixlen, len;
    str_modifiable(str);

    suffixlen = deleted_suffix_length(str, suffix);
    if (suffixlen <= 0) return Qnil;

    olen = RSTRING_LEN(str);
    str_modify_keep_cr(str);
    len = olen - suffixlen;
    STR_SET_LEN(str, len);
    TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
    if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
	ENC_CODERANGE_CLEAR(str);
    }
    return str;
}

#downcase ⇒ `String` #downcase([options]) ⇒ `String`

Returns a copy of str with all uppercase letters replaced with their lowercase counterparts. Which letters exactly are replaced, and by which other letters, depends on the presence or absence of options, and on the encoding of the string.

The meaning of the options is as follows:

No option: Full Unicode case mapping, suitable for most languages (see :turkic and :lithuanian options below for exceptions). Context-dependent case mapping as described in Table 3-14 of the Unicode standard is currently not supported.
:ascii: Only the ASCII region, i.e. the characters “A” to “Z” and “a” to “z”, are affected. This option cannot be combined with any other option.
:turkic: Full Unicode case mapping, adapted for Turkic languages (Turkish, Azerbaijani, …). This means that upper case I is mapped to lower case dotless i, and so on.
:lithuanian: Currently, just full Unicode case mapping. In the future, full Unicode case mapping adapted for Lithuanian (keeping the dot on the lower case i even if there is an accent on top).
:fold: Only available on downcase and downcase!. Unicode case folding, which is more far-reaching than Unicode case mapping. This option currently cannot be combined with any other option (i.e. there is currently no variant for turkic languages).

Please note that several assumptions that are valid for ASCII-only case conversions do not hold for more general case conversions. For example, the length of the result may not be the same as the length of the input (neither in characters nor in bytes), some roundtrip assumptions (e.g. str.downcase == str.upcase.downcase) may not apply, and Unicode normalization (i.e. String#unicode_normalize) is not necessarily maintained by case mapping operations.

Non-ASCII case mapping/folding is currently supported for UTF-8, UTF-16BE/LE, UTF-32BE/LE, and ISO-8859-1~16 Strings/Symbols. This support will be extended to other encodings.

"hEllO".downcase   #=> "hello"

Overloads:

#downcase ⇒ String
Returns:
- (String)
#downcase([options]) ⇒ String
Returns:
- (String)

# File 'string.c', line 7048

static VALUE
rb_str_downcase(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_DOWNCASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        ret = rb_str_new(RSTRING_PTR(str), RSTRING_LEN(str));
        str_enc_copy(ret, str);
        downcase_single(ret);
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }

    return ret;
}

#downcase! ⇒ `String`^? #downcase!([options]) ⇒ `String`^?

Downcases the contents of str, returning nil if no changes were made.

See String#downcase for meaning of options and use with different encodings.

Overloads:

#downcase! ⇒ String^?
Returns:
- (String, nil)
#downcase!([options]) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 6975

static VALUE
rb_str_downcase_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_DOWNCASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        if (downcase_single(str))
            flags |= ONIGENC_CASE_MODIFIED;
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
	str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#dump ⇒ `String`

Returns a quoted version of the string with all non-printing characters replaced by \xHH notation and all special characters escaped.

This method can be used for round-trip: if the resulting new_str is eval’ed, it will produce the original string.

"hello \n ''".dump     #=> "\"hello \\n ''\""
"\f\x00\xff\\\"".dump  #=> "\"\\f\\x00\\xFF\\\\\\\"\""

#each_byte {|integer| ... } ⇒ `String` #each_byte ⇒ `Object`

Passes each byte in str to the given block, or returns an enumerator if no block is given.

"hello".each_byte {|c| print c, ' ' }

produces:

104 101 108 108 111

Overloads:

#each_byte {|integer| ... } ⇒ String
Yields:
- (integer)
Returns:
- (String)

# File 'string.c', line 8674

static VALUE
rb_str_each_byte(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_byte_size);
    return rb_str_enumerate_bytes(str, 0);
}

#each_char {|cstr| ... } ⇒ `String` #each_char ⇒ `Object`

Passes each character in str to the given block, or returns an enumerator if no block is given.

"hello".each_char {|c| print c, ' ' }

produces:

h e l l o

Overloads:

#each_char {|cstr| ... } ⇒ String
Yields:
- (cstr)
Returns:
- (String)

# File 'string.c', line 8752

static VALUE
rb_str_each_char(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_char_size);
    return rb_str_enumerate_chars(str, 0);
}

#each_codepoint {|integer| ... } ⇒ `String` #each_codepoint ⇒ `Object`

Passes the Integer ordinal of each character in str, also known as a codepoint when applied to Unicode strings to the given block. For encodings other than UTF-8/UTF-16(BE|LE)/UTF-32(BE|LE), values are directly derived from the binary representation of each character.

If no block is given, an enumerator is returned instead.

"hello\u0639".each_codepoint {|c| print c, ' ' }

produces:

104 101 108 108 111 1593

Overloads:

#each_codepoint {|integer| ... } ⇒ String
Yields:
- (integer)
Returns:
- (String)

# File 'string.c', line 8826

static VALUE
rb_str_each_codepoint(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_char_size);
    return rb_str_enumerate_codepoints(str, 0);
}

#each_grapheme_cluster {|cstr| ... } ⇒ `String` #each_grapheme_cluster ⇒ `Object`

Passes each grapheme cluster in str to the given block, or returns an enumerator if no block is given. Unlike String#each_char, this enumerates by grapheme clusters defined by Unicode Standard Annex #29 unicode.org/reports/tr29/

"a\u0300".each_char.to_a.size #=> 2
"a\u0300".each_grapheme_cluster.to_a.size #=> 1

Overloads:

#each_grapheme_cluster {|cstr| ... } ⇒ String
Yields:
- (cstr)
Returns:
- (String)

# File 'string.c', line 8976

static VALUE
rb_str_each_grapheme_cluster(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_grapheme_cluster_size);
    return rb_str_enumerate_grapheme_clusters(str, 0);
}

#each_line(separator = $/, chomp: false) {|substr| ... } ⇒ `String` #each_line(separator = $/, chomp: false) ⇒ `Object`

Splits str using the supplied parameter as the record separator ($/ by default), passing each substring in turn to the supplied block. If a zero-length record separator is supplied, the string is split into paragraphs delimited by multiple successive newlines.

If chomp is true, separator will be removed from the end of each line.

If no block is given, an enumerator is returned instead.

"hello\nworld".each_line {|s| p s}
# prints:
#   "hello\n"
#   "world"

"hello\nworld".each_line('l') {|s| p s}
# prints:
#   "hel"
#   "l"
#   "o\nworl"
#   "d"

"hello\n\n\nworld".each_line('') {|s| p s}
# prints
#   "hello\n\n"
#   "world"

"hello\nworld".each_line(chomp: true) {|s| p s}
# prints:
#   "hello"
#   "world"

"hello\nworld".each_line('l', chomp: true) {|s| p s}
# prints:
#   "he"
#   ""
#   "o\nwor"
#   "d"

Overloads:

#each_line(separator = $/, chomp: false) {|substr| ... } ⇒ String
Yields:
- (substr)
Returns:
- (String)

# File 'string.c', line 8606

static VALUE
rb_str_each_line(int argc, VALUE *argv, VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, argc, argv, 0);
    return rb_str_enumerate_lines(argc, argv, str, 0);
}

#empty? ⇒ `Boolean`

Returns true if the length of self is zero, false otherwise:

"hello".empty? # => false
" ".empty? # => false
"".empty? # => true

Returns:

(Boolean)

# File 'string.c', line 2002

static VALUE
rb_str_empty(VALUE str)
{
    if (RSTRING_LEN(str) == 0)
	return Qtrue;
    return Qfalse;
}

#encode(encoding, options) ⇒ `String` #encode(dst_encoding, src_encoding, options) ⇒ `String` #encode(**options) ⇒ `String`

The first form returns a copy of str transcoded to encoding encoding. The second form returns a copy of str transcoded from src_encoding to dst_encoding. The last form returns a copy of str transcoded to Encoding.default_internal.

By default, the first and second form raise Encoding::UndefinedConversionError for characters that are undefined in the destination encoding, and Encoding::InvalidByteSequenceError for invalid byte sequences in the source encoding. The last form by default does not raise exceptions but uses replacement strings.

The options keyword arguments give details for conversion. The arguments are:

:invalid: If the value is :replace, #encode replaces invalid byte sequences in str with the replacement character. The default is to raise the Encoding::InvalidByteSequenceError exception
:undef: If the value is :replace, #encode replaces characters which are undefined in the destination encoding with the replacement character. The default is to raise the Encoding::UndefinedConversionError.
:replace: Sets the replacement string to the given value. The default replacement string is “uFFFD” for Unicode encoding forms, and “?” otherwise.
:fallback: Sets the replacement string by the given object for undefined character. The object should be a Hash, a Proc, a Method, or an object which has [] method. Its key is an undefined character encoded in the source encoding of current transcoder. Its value can be any encoding until it can be converted into the destination encoding of the transcoder.
:xml: The value must be :text or :attr. If the value is :text #encode replaces undefined characters with their (upper-case hexadecimal) numeric character references. ‘&’, ‘<’, and ‘>’ are converted to “&”, “<”, and “>”, respectively. If the value is :attr, #encode also quotes the replacement result (using ‘“’), and replaces ‘”’ with “"”.
:cr_newline: Replaces LF (“n”) with CR (“r”) if value is true.
:crlf_newline: Replaces LF (“n”) with CRLF (“rn”) if value is true.
:universal_newline: Replaces CRLF (“rn”) and CR (“r”) with LF (“n”) if value is true.

Overloads:

#encode(encoding, **options) ⇒ String
Returns:
- (String)
#encode(dst_encoding, src_encoding, **options) ⇒ String
Returns:
- (String)
#encode(**options) ⇒ String
Returns:
- (String)

# File 'transcode.c', line 2877

static VALUE
str_encode(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr = str;
    int encidx = str_transcode(argc, argv, &newstr);
    return encoded_dup(newstr, str, encidx);
}

#encode!(encoding, options) ⇒ `String` #encode!(dst_encoding, src_encoding, options) ⇒ `String`

The first form transcodes the contents of str from str.encoding to encoding. The second form transcodes the contents of str from src_encoding to dst_encoding. The options keyword arguments give details for conversion. See String#encode for details. Returns the string even if no changes were made.

Overloads:

#encode!(encoding, **options) ⇒ String
Returns:
- (String)
#encode!(dst_encoding, src_encoding, **options) ⇒ String
Returns:
- (String)

# File 'transcode.c', line 2799

static VALUE
str_encode_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr;
    int encidx;

    rb_check_frozen(str);

    newstr = str;
    encidx = str_transcode(argc, argv, &newstr);

    if (encidx < 0) return str;
    if (newstr == str) {
	rb_enc_associate_index(str, encidx);
	return str;
    }
    rb_str_shared_replace(str, newstr);
    return str_encode_associate(str, encidx);
}

#encoding ⇒ `Encoding`

Returns the Encoding object that represents the encoding of obj.

Returns:

(Encoding)

# File 'encoding.c', line 1201

VALUE
rb_obj_encoding(VALUE obj)
{
    int idx = rb_enc_get_index(obj);
    if (idx < 0) {
	rb_raise(rb_eTypeError, "unknown encoding");
    }
    return rb_enc_from_encoding_index(idx & ENC_INDEX_MASK);
}

#end_with?([suffixes]) ⇒ `Boolean`

Returns true if str ends with one of the suffixes given.

"hello".end_with?("ello")               #=> true

# returns true if one of the +suffixes+ matches.
"hello".end_with?("heaven", "ello")     #=> true
"hello".end_with?("heaven", "paradise") #=> false

Returns:

(Boolean)

# File 'string.c', line 10168

static VALUE
rb_str_end_with(int argc, VALUE *argv, VALUE str)
{
    int i;
    char *p, *s, *e;
    rb_encoding *enc;

    for (i=0; i<argc; i++) {
	VALUE tmp = argv[i];
	StringValue(tmp);
	enc = rb_enc_check(str, tmp);
	if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
	p = RSTRING_PTR(str);
        e = p + RSTRING_LEN(str);
	s = e - RSTRING_LEN(tmp);
	if (rb_enc_left_char_head(p, s, e, enc) != s)
	    continue;
	if (memcmp(s, RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
	    return Qtrue;
    }
    return Qfalse;
}

#eql?(object) ⇒ `Boolean`

Returns true if object has the same length and content;

as +self+; +false+ otherwise:
  s = 'foo'
  s.eql?('foo') # => true
  s.eql?('food') # => false
  s.eql?('FOO') # => false

Returns +false+ if the two strings' encodings are not compatible:
  "\u{e4 f6 fc}".encode("ISO-8859-1").eql?("\u{c4 d6 dc}") # => false

Returns:

(Boolean)

# File 'string.c', line 3424

MJIT_FUNC_EXPORTED VALUE
rb_str_eql(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;
    return rb_str_eql_internal(str1, str2);
}

#force_encoding(encoding) ⇒ `String`

Changes the encoding to encoding and returns self.

Returns:

(String)

# File 'string.c', line 10384

static VALUE
rb_str_force_encoding(VALUE str, VALUE enc)
{
    str_modifiable(str);
    rb_enc_associate(str, rb_to_encoding(enc));
    ENC_CODERANGE_CLEAR(str);
    return str;
}

#freeze ⇒ `Object`

# File 'string.c', line 2740

VALUE
rb_str_freeze(VALUE str)
{
    if (OBJ_FROZEN(str)) return str;
    rb_str_resize(str, RSTRING_LEN(str));
    return rb_obj_freeze(str);
}

#getbyte(index) ⇒ `0 .. 255`

returns the indexth byte as an integer.

Returns:

(0 .. 255)

# File 'string.c', line 5646

static VALUE
rb_str_getbyte(VALUE str, VALUE index)
{
    long pos = NUM2LONG(index);

    if (pos < 0)
        pos += RSTRING_LEN(str);
    if (pos < 0 ||  RSTRING_LEN(str) <= pos)
        return Qnil;

    return INT2FIX((unsigned char)RSTRING_PTR(str)[pos]);
}

#grapheme_clusters ⇒ `Array`

Returns an array of grapheme clusters in str. This is a shorthand for str.each_grapheme_cluster.to_a.

If a block is given, which is a deprecated form, works the same as each_grapheme_cluster.

Returns:

(Array)

# File 'string.c', line 8994

static VALUE
rb_str_grapheme_clusters(VALUE str)
{
    VALUE ary = WANTARRAY("grapheme_clusters", rb_str_strlen(str));
    return rb_str_enumerate_grapheme_clusters(str, ary);
}

#gsub(pattern, replacement) ⇒ `String` #gsub(pattern, hash) ⇒ `String` #gsub(pattern) {|match| ... } ⇒ `String` #gsub(pattern) ⇒ `Object`

Returns a copy of str with all occurrences of pattern substituted for the second argument. The pattern is typically a Regexp; if given as a String, any regular expression metacharacters it contains will be interpreted literally, e.g. \d will match a backslash followed by ‘d’, instead of a digit.

If replacement is a String it will be substituted for the matched text. It may contain back-references to the pattern’s capture groups of the form \d, where d is a group number, or \k<n>, where n is a group name. Similarly, \&, \', \`, and + correspond to special variables, $&, $', $`, and $+, respectively. (See regexp.rdoc for details.) \0 is the same as \&. \\ is interpreted as an escape, i.e., a single backslash. Note that, within replacement the special match variables, such as $&, will not refer to the current match.

If the second argument is a Hash, and the matched text is one of its keys, the corresponding value is the replacement string.

In the block form, the current match string is passed in as a parameter, and variables such as $1, $2, $`, $&, and $' will be set appropriately. (See regexp.rdoc for details.) The value returned by the block will be substituted for the match on each call.

When neither a block nor a second argument is supplied, an Enumerator is returned.

"hello".gsub(/[aeiou]/, '*')                  #=> "h*ll*"
"hello".gsub(/([aeiou])/, '<\1>')             #=> "h<e>ll<o>"
"hello".gsub(/./) {|s| s.ord.to_s + ' '}      #=> "104 101 108 108 111 "
"hello".gsub(/(?<foo>[aeiou])/, '{\k<foo>}')  #=> "h{e}ll{o}"
'hello'.gsub(/[eo]/, 'e' => 3, 'o' => '*')    #=> "h3ll*"

Note that a string literal consumes backslashes. (See syntax/literals.rdoc for details on string literals.) Back-references are typically preceded by an additional backslash. For example, if you want to write a back-reference \& in replacement with a double-quoted string literal, you need to write: "..\\&..". If you want to write a non-back-reference string \& in replacement, you need first to escape the backslash to prevent this method from interpreting it as a back-reference, and then you need to escape the backslashes again to prevent a string literal from consuming them: "..\\\\&..". You may want to use the block form to avoid a lot of backslashes.

Overloads:

#gsub(pattern, replacement) ⇒ String
Returns:
- (String)
#gsub(pattern, hash) ⇒ String
Returns:
- (String)
#gsub(pattern) {|match| ... } ⇒ String
Yields:
- (match)
Returns:
- (String)

# File 'string.c', line 5571

static VALUE
rb_str_gsub(int argc, VALUE *argv, VALUE str)
{
    return str_gsub(argc, argv, str, 0);
}

#gsub!(pattern, replacement) ⇒ `String`^? #gsub!(pattern, hash) ⇒ `String`^? #gsub!(pattern) {|match| ... } ⇒ `String`^? #gsub!(pattern) ⇒ `Object`

Performs the substitutions of String#gsub in place, returning str, or nil if no substitutions were performed. If no block and no replacement is given, an enumerator is returned instead.

Overloads:

#gsub!(pattern, replacement) ⇒ String^?
Returns:
- (String, nil)
#gsub!(pattern, hash) ⇒ String^?
Returns:
- (String, nil)
#gsub!(pattern) {|match| ... } ⇒ String^?
Yields:
- (match)
Returns:
- (String, nil)

# File 'string.c', line 5503

static VALUE
rb_str_gsub_bang(int argc, VALUE *argv, VALUE str)
{
    str_modify_keep_cr(str);
    return str_gsub(argc, argv, str, 1);
}

#hash ⇒ `Integer`

Returns the integer hash value for self. The value is based on the length, content and encoding of self.

Returns:

(Integer)

# File 'string.c', line 3317

static VALUE
rb_str_hash_m(VALUE str)
{
    st_index_t hval = rb_str_hash(str);
    return ST2FIX(hval);
}

#hex ⇒ `Integer`

Treats leading characters from str as a string of hexadecimal digits (with an optional sign and an optional 0x) and returns the corresponding number. Zero is returned on error.

"0x0a".hex     #=> 10
"-1234".hex    #=> -4660
"0".hex        #=> 0
"wombat".hex   #=> 0

Returns:

(Integer)

# File 'string.c', line 9642

static VALUE
rb_str_hex(VALUE str)
{
    return rb_str_to_inum(str, 16, FALSE);
}

#include?(other_str) ⇒ `Boolean`

Returns true if str contains the given string or character.

"hello".include? "lo"   #=> true
"hello".include? "ol"   #=> false
"hello".include? ?h     #=> true

Returns:

(Boolean)

# File 'string.c', line 5941

static VALUE
rb_str_include(VALUE str, VALUE arg)
{
    long i;

    StringValue(arg);
    i = rb_str_index(str, arg, 0);

    if (i == -1) return Qfalse;
    return Qtrue;
}

#index(substring, offset = 0) ⇒ `Integer`^? #index(regexp, offset = 0) ⇒ `Integer`^?

Returns the Integer index of the first occurrence of the given substring, or nil if none found:

'foo'.index('f') # => 0
'foo'.index('o') # => 1
'foo'.index('oo') # => 1
'foo'.index('ooo') # => nil

Returns the Integer index of the first match for the given Regexp regexp, or nil if none found:

'foo'.index(/f/) # => 0
'foo'.index(/o/) # => 1
'foo'.index(/oo/) # => 1
'foo'.index(/ooo/) # => nil

Integer argument offset, if given, specifies the position in the string to begin the search:

'foo'.index('o', 1) # => 1
'foo'.index('o', 2) # => 2
'foo'.index('o', 3) # => nil

If offset is negative, counts backward from the end of self:

'foo'.index('o', -1) # => 2
'foo'.index('o', -2) # => 1
'foo'.index('o', -3) # => 1
'foo'.index('o', -4) # => nil

Related: String#rindex

Overloads:

#index(substring, offset = 0) ⇒ Integer^?
Returns:
- (Integer, nil)
#index(regexp, offset = 0) ⇒ Integer^?
Returns:
- (Integer, nil)

# File 'string.c', line 3691

static VALUE
rb_str_index_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE initpos;
    long pos;

    if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
	pos = NUM2LONG(initpos);
    }
    else {
	pos = 0;
    }
    if (pos < 0) {
	pos += str_strlen(str, NULL);
	if (pos < 0) {
	    if (RB_TYPE_P(sub, T_REGEXP)) {
		rb_backref_set(Qnil);
	    }
	    return Qnil;
	}
    }

    if (RB_TYPE_P(sub, T_REGEXP)) {
	if (pos > str_strlen(str, NULL))
	    return Qnil;
	pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
			 rb_enc_check(str, sub), single_byte_optimizable(str));

	if (rb_reg_search(sub, str, pos, 0) < 0) {
            return Qnil;
        } else {
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            pos = rb_str_sublen(str, BEG(0));
            return LONG2NUM(pos);
        }
    }
    else {
        StringValue(sub);
	pos = rb_str_index(str, sub, pos);
	pos = rb_str_sublen(str, pos);
    }

    if (pos == -1) return Qnil;
    return LONG2NUM(pos);
}

#replace(other_str) ⇒ `String`

Replaces the contents of str with the corresponding values in other_str.

s = "hello"         #=> "hello"
s.replace "world"   #=> "world"

Returns:

(String)

# File 'string.c', line 5589

VALUE
rb_str_replace(VALUE str, VALUE str2)
{
    str_modifiable(str);
    if (str == str2) return str;

    StringValue(str2);
    str_discard(str);
    return str_replace(str, str2);
}

#insert(index, other_string) ⇒ `self`

Inserts the given other_string into self; returns self.

If the Integer index is positive, inserts other_string at offset index:

'foo'.insert(1, 'bar') # => "fbaroo"

If the Integer index is negative, counts backward from the end of self and inserts other_string at offset index+1 (that is, after self[index]):

'foo'.insert(-2, 'bar') # => "fobaro"

Returns:

(self)

# File 'string.c', line 4991

static VALUE
rb_str_insert(VALUE str, VALUE idx, VALUE str2)
{
    long pos = NUM2LONG(idx);

    if (pos == -1) {
	return rb_str_append(str, str2);
    }
    else if (pos < 0) {
	pos++;
    }
    rb_str_splice(str, pos, 0, str2);
    return str;
}

#inspect ⇒ `String`

Returns a printable version of str, surrounded by quote marks, with special characters escaped.

str = "hello"
str[3] = "\b"
str.inspect       #=> "\"hel\\bo\""

Returns:

(String)

# File 'string.c', line 6156

VALUE
rb_str_inspect(VALUE str)
{
    int encidx = ENCODING_GET(str);
    rb_encoding *enc = rb_enc_from_index(encidx), *actenc;
    const char *p, *pend, *prev;
    char buf[CHAR_ESC_LEN + 1];
    VALUE result = rb_str_buf_new(0);
    rb_encoding *resenc = rb_default_internal_encoding();
    int unicode_p = rb_enc_unicode_p(enc);
    int asciicompat = rb_enc_asciicompat(enc);

    if (resenc == NULL) resenc = rb_default_external_encoding();
    if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
    rb_enc_associate(result, resenc);
    str_buf_cat2(result, "\"");

    p = RSTRING_PTR(str); pend = RSTRING_END(str);
    prev = p;
    actenc = get_actual_encoding(encidx, str);
    if (actenc != enc) {
	enc = actenc;
	if (unicode_p) unicode_p = rb_enc_unicode_p(enc);
    }
    while (p < pend) {
	unsigned int c, cc;
	int n;

        n = rb_enc_precise_mbclen(p, pend, enc);
        if (!MBCLEN_CHARFOUND_P(n)) {
	    if (p > prev) str_buf_cat(result, prev, p - prev);
            n = rb_enc_mbminlen(enc);
            if (pend < p + n)
                n = (int)(pend - p);
            while (n--) {
                snprintf(buf, CHAR_ESC_LEN, "\\x%02X", *p & 0377);
                str_buf_cat(result, buf, strlen(buf));
                prev = ++p;
            }
	    continue;
	}
        n = MBCLEN_CHARFOUND_LEN(n);
	c = rb_enc_mbc_to_codepoint(p, pend, enc);
	p += n;
	if ((asciicompat || unicode_p) &&
	  (c == '"'|| c == '\\' ||
	    (c == '#' &&
             p < pend &&
             MBCLEN_CHARFOUND_P(rb_enc_precise_mbclen(p,pend,enc)) &&
             (cc = rb_enc_codepoint(p,pend,enc),
              (cc == '$' || cc == '@' || cc == '{'))))) {
	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
	    str_buf_cat2(result, "\\");
	    if (asciicompat || enc == resenc) {
		prev = p - n;
		continue;
	    }
	}
	switch (c) {
	  case '\n': cc = 'n'; break;
	  case '\r': cc = 'r'; break;
	  case '\t': cc = 't'; break;
	  case '\f': cc = 'f'; break;
	  case '\013': cc = 'v'; break;
	  case '\010': cc = 'b'; break;
	  case '\007': cc = 'a'; break;
	  case 033: cc = 'e'; break;
	  default: cc = 0; break;
	}
	if (cc) {
	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
	    buf[0] = '\\';
	    buf[1] = (char)cc;
	    str_buf_cat(result, buf, 2);
	    prev = p;
	    continue;
	}
	if ((enc == resenc && rb_enc_isprint(c, enc)) ||
	    (asciicompat && rb_enc_isascii(c, enc) && ISPRINT(c))) {
	    continue;
	}
	else {
	    if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
	    rb_str_buf_cat_escaped_char(result, c, unicode_p);
	    prev = p;
	    continue;
	}
    }
    if (p > prev) str_buf_cat(result, prev, p - prev);
    str_buf_cat2(result, "\"");

    return result;
}

#intern ⇒ `Object` #to_sym ⇒ `Object`

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name.

"Koala".intern         #=> :Koala
s = 'cat'.to_sym       #=> :cat
s == :cat              #=> true
s = '@cat'.to_sym      #=> :@cat
s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the :xxx notation.

'cat and dog'.to_sym   #=> :"cat and dog"

# File 'symbol.c', line 839

VALUE
rb_str_intern(VALUE str)
{
    VALUE sym;
#if USE_SYMBOL_GC
    rb_encoding *enc, *ascii;
    int type;
#else
    ID id;
#endif
    GLOBAL_SYMBOLS_ENTER(symbols);
    {
        sym = lookup_str_sym_with_lock(symbols, str);

        if (sym) {
            // ok
        }
        else {
#if USE_SYMBOL_GC
            enc = rb_enc_get(str);
            ascii = rb_usascii_encoding();
            if (enc != ascii && sym_check_asciionly(str)) {
                str = rb_str_dup(str);
                rb_enc_associate(str, ascii);
                OBJ_FREEZE(str);
                enc = ascii;
            }
            else {
                str = rb_str_dup(str);
                OBJ_FREEZE(str);
            }
            str = rb_fstring(str);
            type = rb_str_symname_type(str, IDSET_ATTRSET_FOR_INTERN);
            if (type < 0) type = ID_JUNK;
            sym = dsymbol_alloc(symbols, rb_cSymbol, str, enc, type);
#else
            id = intern_str(str, 0);
            sym = ID2SYM(id);
#endif
        }
    }
    GLOBAL_SYMBOLS_LEAVE();
    return sym;
}

#length ⇒ `Integer`

Returns the count of characters (not bytes) in self:

"\x80\u3042".length # => 2
"hello".length # => 5

String#size is an alias for String#length.

Related: String#bytesize.

Returns:

(Integer)

# File 'string.c', line 1969

VALUE
rb_str_length(VALUE str)
{
    return LONG2NUM(str_strlen(str, NULL));
}

#lines(separator = $/, chomp: false) ⇒ `Array`

Returns an array of lines in str split using the supplied record separator ($/ by default). This is a shorthand for str.each_line(separator, getline_args).to_a.

If chomp is true, separator will be removed from the end of each line.

"hello\nworld\n".lines              #=> ["hello\n", "world\n"]
"hello  world".lines(' ')           #=> ["hello ", " ", "world"]
"hello\nworld\n".lines(chomp: true) #=> ["hello", "world"]

If a block is given, which is a deprecated form, works the same as each_line.

Returns:

(Array)

# File 'string.c', line 8632

static VALUE
rb_str_lines(int argc, VALUE *argv, VALUE str)
{
    VALUE ary = WANTARRAY("lines", 0);
    return rb_str_enumerate_lines(argc, argv, str, ary);
}

#ljust(integer, padstr = ' ') ⇒ `String`

If integer is greater than the length of str, returns a new String of length integer with str left justified and padded with padstr; otherwise, returns str.

"hello".ljust(4)            #=> "hello"
"hello".ljust(20)           #=> "hello               "
"hello".ljust(20, '1234')   #=> "hello123412341234123"

Returns:

(String)

# File 'string.c', line 9980

static VALUE
rb_str_ljust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'l');
}

#lstrip ⇒ `String`

Returns a copy of the receiver with leading whitespace removed. See also String#rstrip and String#strip.

Refer to String#strip for the definition of whitespace.

"  hello  ".lstrip   #=> "hello  "
"hello".lstrip       #=> "hello"

Returns:

(String)

# File 'string.c', line 9335

static VALUE
rb_str_lstrip(VALUE str)
{
    char *start;
    long len, loffset;
    RSTRING_GETMEM(str, start, len);
    loffset = lstrip_offset(str, start, start+len, STR_ENC_GET(str));
    if (loffset <= 0) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, loffset, len - loffset);
}

#lstrip! ⇒ `self`^?

Removes leading whitespace from the receiver. Returns the altered receiver, or nil if no change was made. See also String#rstrip! and String#strip!.

Refer to String#strip for the definition of whitespace.

"  hello  ".lstrip!  #=> "hello  "
"hello  ".lstrip!    #=> nil
"hello".lstrip!      #=> nil

Returns:

(self, nil)

# File 'string.c', line 9297

static VALUE
rb_str_lstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *start, *s;
    long olen, loffset;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    loffset = lstrip_offset(str, start, start+olen, enc);
    if (loffset > 0) {
	long len = olen-loffset;
	s = start + loffset;
	memmove(start, s, len);
	STR_SET_LEN(str, len);
#if !SHARABLE_MIDDLE_SUBSTRING
	TERM_FILL(start+len, rb_enc_mbminlen(enc));
#endif
	return str;
    }
    return Qnil;
}

#match(pattern, offset = 0) ⇒ `MatchData`^? #match(pattern, offset = 0) {|matchdata| ... } ⇒ `Object`

Returns a Matchdata object (or nil) based on self and the given pattern.

Note: also updates Regexp-related global variables.

Computes regexp by converting pattern (if not already a Regexp).
```
regexp = Regexp.new(pattern)
```
Computes matchdata, which will be either a MatchData object or nil (see Regexp#match):
```
matchdata = <tt>regexp.match(self)
```

With no block given, returns the computed matchdata:

'foo'.match('f') # => #<MatchData "f">
'foo'.match('o') # => #<MatchData "o">
'foo'.match('x') # => nil

If Integer argument offset is given, the search begins at index offset:

'foo'.match('f', 1) # => nil
'foo'.match('o', 1) # => #<MatchData "o">

With a block given, calls the block with the computed matchdata and returns the block’s return value:

'foo'.match(/o/) {|matchdata| matchdata } # => #<MatchData "o">
'foo'.match(/x/) {|matchdata| matchdata } # => nil
'foo'.match(/f/, 1) {|matchdata| matchdata } # => nil

Overloads:

#match(pattern, offset = 0) ⇒ MatchData^?
Returns:
- (MatchData, nil)
#match(pattern, offset = 0) {|matchdata| ... } ⇒ Object
Yields:
- (matchdata)
Returns:
- (Object)

# File 'string.c', line 3987

static VALUE
rb_str_match_m(int argc, VALUE *argv, VALUE str)
{
    VALUE re, result;
    if (argc < 1)
	rb_check_arity(argc, 1, 2);
    re = argv[0];
    argv[0] = str;
    result = rb_funcallv(get_pat(re), rb_intern("match"), argc, argv);
    if (!NIL_P(result) && rb_block_given_p()) {
	return rb_yield(result);
    }
    return result;
}

#match?(pattern, offset = 0) ⇒ `Boolean`

Returns true or false based on whether a match is found for self and pattern.

Note: does not update Regexp-related global variables.

Computes regexp by converting pattern (if not already a Regexp).

regexp = Regexp.new(pattern)

Returns true if self+.match(regexp) returns a Matchdata object, false otherwise:

'foo'.match?(/o/) # => true
'foo'.match?('o') # => true
'foo'.match?(/x/) # => false

If Integer argument offset is given, the search begins at index offset:

'foo'.match?('f', 1) # => false
'foo'.match?('o', 1) # => true

Returns:

(Boolean)

# File 'string.c', line 4025

static VALUE
rb_str_match_m_p(int argc, VALUE *argv, VALUE str)
{
    VALUE re;
    rb_check_arity(argc, 1, 2);
    re = get_pat(argv[0]);
    return rb_reg_match_p(re, str, argc > 1 ? NUM2LONG(argv[1]) : 0);
}

#succ ⇒ `String`

Returns the successor to self. The successor is calculated by incrementing characters.

The first character to be incremented is the rightmost alphanumeric: or, if no alphanumerics, the rightmost character:

'THX1138'.succ # => "THX1139"
'<<koala>>'.succ # => "<<koalb>>"
'***'.succ # => '**+'

The successor to a digit is another digit, “carrying” to the next-left character for a “rollover” from 9 to 0, and prepending another digit if necessary:

'00'.succ # => "01"
'09'.succ # => "10"
'99'.succ # => "100"

The successor to a letter is another letter of the same case, carrying to the next-left character for a rollover, and prepending another same-case letter if necessary:

'aa'.succ # => "ab"
'az'.succ # => "ba"
'zz'.succ # => "aaa"
'AA'.succ # => "AB"
'AZ'.succ # => "BA"
'ZZ'.succ # => "AAA"

The successor to a non-alphanumeric character is the next character in the underlying character set’s collating sequence, carrying to the next-left character for a rollover, and prepending another character if necessary:

s = 0.chr * 3
s # => "\x00\x00\x00"
s.succ # => "\x00\x00\x01"
s = 255.chr * 3
s # => "\xFF\xFF\xFF"
s.succ # => "\x01\x00\x00\x00"

Carrying can occur between and among mixtures of alphanumeric characters:

s = 'zz99zz99'
s.succ # => "aaa00aa00"
s = '99zz99zz'
s.succ # => "100aa00aa"

The successor to an empty String is a new empty String:

''.succ # => ""

String#next is an alias for String#succ.

Returns:

(String)

# File 'string.c', line 4272

VALUE
rb_str_succ(VALUE orig)
{
    VALUE str;
    str = rb_str_new(RSTRING_PTR(orig), RSTRING_LEN(orig));
    rb_enc_cr_str_copy_for_substr(str, orig);
    return str_succ(str);
}

#succ! ⇒ `self`

Equivalent to String#succ, but modifies self in place; returns self.

String#next! is an alias for String#succ!.

Returns:

(self)

# File 'string.c', line 4378

static VALUE
rb_str_succ_bang(VALUE str)
{
    rb_str_modify(str);
    str_succ(str);
    return str;
}

#oct ⇒ `Integer`

Treats leading characters of str as a string of octal digits (with an optional sign) and returns the corresponding number. Returns 0 if the conversion fails.

"123".oct       #=> 83
"-377".oct      #=> -255
"bad".oct       #=> 0
"0377bad".oct   #=> 255

If str starts with 0, radix indicators are honored. See Kernel#Integer.

Returns:

(Integer)

# File 'string.c', line 9666

static VALUE
rb_str_oct(VALUE str)
{
    return rb_str_to_inum(str, -8, FALSE);
}

#ord ⇒ `Integer`

Returns the Integer ordinal of a one-character string.

"a".ord         #=> 97

Returns:

(Integer)

# File 'string.c', line 9802

static VALUE
rb_str_ord(VALUE s)
{
    unsigned int c;

    c = rb_enc_codepoint(RSTRING_PTR(s), RSTRING_END(s), STR_ENC_GET(s));
    return UINT2NUM(c);
}

#partition(sep) ⇒ `Array` #partition(regexp) ⇒ `Array`

Searches sep or pattern (regexp) in the string and returns the part before it, the match, and the part after it. If it is not found, returns two empty strings and str.

"hello".partition("l")         #=> ["he", "l", "lo"]
"hello".partition("x")         #=> ["hello", "", ""]
"hello".partition(/.l/)        #=> ["h", "el", "lo"]

Overloads:

#partition(sep) ⇒ Array
Returns:
- (Array)
#partition(regexp) ⇒ Array
Returns:
- (Array)

# File 'string.c', line 10041

static VALUE
rb_str_partition(VALUE str, VALUE sep)
{
    long pos;

    sep = get_pat_quoted(sep, 0);
    if (RB_TYPE_P(sep, T_REGEXP)) {
	if (rb_reg_search(sep, str, 0, 0) < 0) {
            goto failed;
	}
	VALUE match = rb_backref_get();
	struct re_registers *regs = RMATCH_REGS(match);

        pos = BEG(0);
	sep = rb_str_subseq(str, pos, END(0) - pos);
    }
    else {
	pos = rb_str_index(str, sep, 0);
	if (pos < 0) goto failed;
    }
    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
		          sep,
		          rb_str_subseq(str, pos+RSTRING_LEN(sep),
					     RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));

  failed:
    return rb_ary_new3(3, str_duplicate(rb_cString, str), str_new_empty_String(str), str_new_empty_String(str));
}

#prepend(*other_strings) ⇒ `String`

Returns a new String containing the concatenation of all given other_strings and self:

s = 'foo'
s.prepend('bar', 'baz') # => "barbazfoo"

Related: String#concat.

Returns:

(String)

# File 'string.c', line 3266

static VALUE
rb_str_prepend_multi(int argc, VALUE *argv, VALUE str)
{
    str_modifiable(str);

    if (argc == 1) {
	rb_str_update(str, 0L, 0L, argv[0]);
    }
    else if (argc > 1) {
	int i;
	VALUE arg_str = rb_str_tmp_new(0);
	rb_enc_copy(arg_str, str);
	for (i = 0; i < argc; i++) {
	    rb_str_append(arg_str, argv[i]);
	}
	rb_str_update(str, 0L, 0L, arg_str);
    }

    return str;
}

#replace(other_str) ⇒ `String`

Replaces the contents of str with the corresponding values in other_str.

s = "hello"         #=> "hello"
s.replace "world"   #=> "world"

Returns:

(String)

# File 'string.c', line 5589

VALUE
rb_str_replace(VALUE str, VALUE str2)
{
    str_modifiable(str);
    if (str == str2) return str;

    StringValue(str2);
    str_discard(str);
    return str_replace(str, str2);
}

#reverse ⇒ `String`

Returns a new string with the characters from str in reverse order.

"stressed".reverse   #=> "desserts"

Returns:

(String)

# File 'string.c', line 5844

static VALUE
rb_str_reverse(VALUE str)
{
    rb_encoding *enc;
    VALUE rev;
    char *s, *e, *p;
    int cr;

    if (RSTRING_LEN(str) <= 1) return str_duplicate(rb_cString, str);
    enc = STR_ENC_GET(str);
    rev = rb_str_new(0, RSTRING_LEN(str));
    s = RSTRING_PTR(str); e = RSTRING_END(str);
    p = RSTRING_END(rev);
    cr = ENC_CODERANGE(str);

    if (RSTRING_LEN(str) > 1) {
	if (single_byte_optimizable(str)) {
	    while (s < e) {
		*--p = *s++;
	    }
	}
	else if (cr == ENC_CODERANGE_VALID) {
	    while (s < e) {
		int clen = rb_enc_fast_mbclen(s, e, enc);

		p -= clen;
		memcpy(p, s, clen);
		s += clen;
	    }
	}
	else {
	    cr = rb_enc_asciicompat(enc) ?
		ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
	    while (s < e) {
		int clen = rb_enc_mbclen(s, e, enc);

		if (clen > 1 || (*s & 0x80)) cr = ENC_CODERANGE_UNKNOWN;
		p -= clen;
		memcpy(p, s, clen);
		s += clen;
	    }
	}
    }
    STR_SET_LEN(rev, RSTRING_LEN(str));
    str_enc_copy(rev, str);
    ENC_CODERANGE_SET(rev, cr);

    return rev;
}

#reverse! ⇒ `String`

Reverses str in place.

Returns:

(String)

# File 'string.c', line 5902

static VALUE
rb_str_reverse_bang(VALUE str)
{
    if (RSTRING_LEN(str) > 1) {
	if (single_byte_optimizable(str)) {
	    char *s, *e, c;

	    str_modify_keep_cr(str);
	    s = RSTRING_PTR(str);
	    e = RSTRING_END(str) - 1;
	    while (s < e) {
		c = *s;
		*s++ = *e;
		*e-- = c;
	    }
	}
	else {
	    str_shared_replace(str, rb_str_reverse(str));
	}
    }
    else {
	str_modify_keep_cr(str);
    }
    return str;
}

#rindex(substring, offset = self.length) ⇒ `Integer`^? #rindex(regexp, offset = self.length) ⇒ `Integer`^?

Returns the Integer index of the last occurrence of the given substring, or nil if none found:

'foo'.rindex('f') # => 0
'foo'.rindex('o') # => 2
'foo'.rindex('oo') # => 1
'foo'.rindex('ooo') # => nil

Returns the Integer index of the last match for the given Regexp regexp, or nil if none found:

'foo'.rindex(/f/) # => 0
'foo'.rindex(/o/) # => 2
'foo'.rindex(/oo/) # => 1
'foo'.rindex(/ooo/) # => nil

Integer argument offset, if given and non-negative, specifies the maximum starting position in the

string to _end_ the search:
 'foo'.rindex('o', 0) # => nil
 'foo'.rindex('o', 1) # => 1
 'foo'.rindex('o', 2) # => 2
 'foo'.rindex('o', 3) # => 2

If offset is a negative Integer, the maximum starting position in the string to end the search is the sum of the string’s length and offset:

'foo'.rindex('o', -1) # => 2
'foo'.rindex('o', -2) # => 1
'foo'.rindex('o', -3) # => nil
'foo'.rindex('o', -4) # => nil

Related: String#index

Overloads:

#rindex(substring, offset = self.length) ⇒ Integer^?
Returns:
- (Integer, nil)
#rindex(regexp, offset = self.length) ⇒ Integer^?
Returns:
- (Integer, nil)

# File 'string.c', line 3865

static VALUE
rb_str_rindex_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE vpos;
    rb_encoding *enc = STR_ENC_GET(str);
    long pos, len = str_strlen(str, enc); /* str's enc */

    if (rb_scan_args(argc, argv, "11", &sub, &vpos) == 2) {
	pos = NUM2LONG(vpos);
	if (pos < 0) {
	    pos += len;
	    if (pos < 0) {
		if (RB_TYPE_P(sub, T_REGEXP)) {
		    rb_backref_set(Qnil);
		}
		return Qnil;
	    }
	}
	if (pos > len) pos = len;
    }
    else {
	pos = len;
    }

    if (RB_TYPE_P(sub, T_REGEXP)) {
	/* enc = rb_get_check(str, sub); */
	pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
			 enc, single_byte_optimizable(str));

	if (rb_reg_search(sub, str, pos, 1) >= 0) {
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            pos = rb_str_sublen(str, BEG(0));
            return LONG2NUM(pos);
        }
    }
    else {
        StringValue(sub);
	pos = rb_str_rindex(str, sub, pos);
	if (pos >= 0) return LONG2NUM(pos);
    }
    return Qnil;
}

#rjust(integer, padstr = ' ') ⇒ `String`

If integer is greater than the length of str, returns a new String of length integer with str right justified and padded with padstr; otherwise, returns str.

"hello".rjust(4)            #=> "hello"
"hello".rjust(20)           #=> "               hello"
"hello".rjust(20, '1234')   #=> "123412341234123hello"

Returns:

(String)

# File 'string.c', line 10000

static VALUE
rb_str_rjust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'r');
}

#rpartition(sep) ⇒ `Array` #rpartition(regexp) ⇒ `Array`

Searches sep or pattern (regexp) in the string from the end of the string, and returns the part before it, the match, and the part after it. If it is not found, returns two empty strings and str.

"hello".rpartition("l")         #=> ["hel", "l", "o"]
"hello".rpartition("x")         #=> ["", "", "hello"]
"hello".rpartition(/.l/)        #=> ["he", "ll", "o"]

Overloads:

#rpartition(sep) ⇒ Array
Returns:
- (Array)
#rpartition(regexp) ⇒ Array
Returns:
- (Array)

# File 'string.c', line 10085

static VALUE
rb_str_rpartition(VALUE str, VALUE sep)
{
    long pos = RSTRING_LEN(str);

    sep = get_pat_quoted(sep, 0);
    if (RB_TYPE_P(sep, T_REGEXP)) {
        if (rb_reg_search(sep, str, pos, 1) < 0) {
            goto failed;
        }
        VALUE match = rb_backref_get();
	struct re_registers *regs = RMATCH_REGS(match);

        pos = BEG(0);
        sep = rb_str_subseq(str, pos, END(0) - pos);
    }
    else {
	pos = rb_str_sublen(str, pos);
	pos = rb_str_rindex(str, sep, pos);
        if(pos < 0) {
            goto failed;
        }
        pos = rb_str_offset(str, pos);
    }

    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
		          sep,
		          rb_str_subseq(str, pos+RSTRING_LEN(sep),
					RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));
  failed:
    return rb_ary_new3(3, str_new_empty_String(str), str_new_empty_String(str), str_duplicate(rb_cString, str));
}

#rstrip ⇒ `String`

Returns a copy of the receiver with trailing whitespace removed. See also String#lstrip and String#strip.

Refer to String#strip for the definition of whitespace.

"  hello  ".rstrip   #=> "  hello"
"hello".rstrip       #=> "hello"

Returns:

(String)

# File 'string.c', line 9424

static VALUE
rb_str_rstrip(VALUE str)
{
    rb_encoding *enc;
    char *start;
    long olen, roffset;

    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    roffset = rstrip_offset(str, start, start+olen, enc);

    if (roffset <= 0) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, 0, olen-roffset);
}

#rstrip! ⇒ `self`^?

Removes trailing whitespace from the receiver. Returns the altered receiver, or nil if no change was made. See also String#lstrip! and String#strip!.

Refer to String#strip for the definition of whitespace.

"  hello  ".rstrip!  #=> "  hello"
"  hello".rstrip!    #=> nil
"hello".rstrip!      #=> nil

Returns:

(self, nil)

# File 'string.c', line 9387

static VALUE
rb_str_rstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *start;
    long olen, roffset;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    roffset = rstrip_offset(str, start, start+olen, enc);
    if (roffset > 0) {
	long len = olen - roffset;

	STR_SET_LEN(str, len);
#if !SHARABLE_MIDDLE_SUBSTRING
	TERM_FILL(start+len, rb_enc_mbminlen(enc));
#endif
	return str;
    }
    return Qnil;
}

#scan(pattern) ⇒ `Array` #scan(pattern) {|match, ...| ... } ⇒ `String`

Both forms iterate through str, matching the pattern (which may be a Regexp or a String). For each match, a result is generated and either added to the result array or passed to the block. If the pattern contains no groups, each individual result consists of the matched string, $&. If the pattern contains groups, each individual result is itself an array containing one entry per group.

a = "cruel world"
a.scan(/\w+/)        #=> ["cruel", "world"]
a.scan(/.../)        #=> ["cru", "el ", "wor"]
a.scan(/(...)/)      #=> [["cru"], ["el "], ["wor"]]
a.scan(/(..)(..)/)   #=> [["cr", "ue"], ["l ", "wo"]]

And the block form:

a.scan(/\w+/) {|w| print "<<#{w}>> " }
print "\n"
a.scan(/(.)(.)/) {|x,y| print y, x }
print "\n"

produces:

<<cruel>> <<world>>
rceu lowlr

Overloads:

#scan(pattern) ⇒ Array
Returns:
- (Array)
#scan(pattern) {|match, ...| ... } ⇒ String
Yields:
- (match, ...)
Returns:
- (String)

# File 'string.c', line 9594

static VALUE
rb_str_scan(VALUE str, VALUE pat)
{
    VALUE result;
    long start = 0;
    long last = -1, prev = 0;
    char *p = RSTRING_PTR(str); long len = RSTRING_LEN(str);

    pat = get_pat_quoted(pat, 1);
    mustnot_broken(str);
    if (!rb_block_given_p()) {
	VALUE ary = rb_ary_new();

	while (!NIL_P(result = scan_once(str, pat, &start, 0))) {
	    last = prev;
	    prev = start;
	    rb_ary_push(ary, result);
	}
	if (last >= 0) rb_pat_search(pat, str, last, 1);
	else rb_backref_set(Qnil);
	return ary;
    }

    while (!NIL_P(result = scan_once(str, pat, &start, 1))) {
	last = prev;
	prev = start;
	rb_yield(result);
	str_mod_check(str, p, len);
    }
    if (last >= 0) rb_pat_search(pat, str, last, 1);
    return str;
}

#scrub ⇒ `String` #scrub(repl) ⇒ `String` #scrub {|bytes| ... } ⇒ `String`

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self. If block is given, replace invalid bytes with returned value of the block.

"abc\u3042\x81".scrub #=> "abc\u3042\uFFFD"
"abc\u3042\x81".scrub("*") #=> "abc\u3042*"
"abc\u3042\xE3\x80".scrub{|bytes| '<'+bytes.unpack('H*')[0]+'>' } #=> "abc\u3042<e380>"

Overloads:

#scrub ⇒ String
Returns:
- (String)
#scrub(repl) ⇒ String
Returns:
- (String)
#scrub {|bytes| ... } ⇒ String
Yields:
- (bytes)
Returns:
- (String)

# File 'string.c', line 10798

static VALUE
str_scrub(int argc, VALUE *argv, VALUE str)
{
    VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
    VALUE new = rb_str_scrub(str, repl);
    return NIL_P(new) ? str_duplicate(rb_cString, str): new;
}

#scrub! ⇒ `String` #scrub!(repl) ⇒ `String` #scrub! {|bytes| ... } ⇒ `String`

If the string is invalid byte sequence then replace invalid bytes with given replacement character, else returns self. If block is given, replace invalid bytes with returned value of the block.

"abc\u3042\x81".scrub! #=> "abc\u3042\uFFFD"
"abc\u3042\x81".scrub!("*") #=> "abc\u3042*"
"abc\u3042\xE3\x80".scrub!{|bytes| '<'+bytes.unpack('H*')[0]+'>' } #=> "abc\u3042<e380>"

Overloads:

#scrub! ⇒ String
Returns:
- (String)
#scrub!(repl) ⇒ String
Returns:
- (String)
#scrub! {|bytes| ... } ⇒ String
Yields:
- (bytes)
Returns:
- (String)

# File 'string.c', line 10820

static VALUE
str_scrub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
    VALUE new = rb_str_scrub(str, repl);
    if (!NIL_P(new)) rb_str_replace(str, new);
    return str;
}

#setbyte(index, integer) ⇒ `Integer`

modifies the indexth byte as integer.

Returns:

(Integer)

# File 'string.c', line 5665

static VALUE
rb_str_setbyte(VALUE str, VALUE index, VALUE value)
{
    long pos = NUM2LONG(index);
    long len = RSTRING_LEN(str);
    char *head, *left = 0;
    unsigned char *ptr;
    rb_encoding *enc;
    int cr = ENC_CODERANGE_UNKNOWN, width, nlen;

    if (pos < -len || len <= pos)
        rb_raise(rb_eIndexError, "index %ld out of string", pos);
    if (pos < 0)
        pos += len;

    VALUE v = rb_to_int(value);
    VALUE w = rb_int_and(v, INT2FIX(0xff));
    unsigned char byte = NUM2INT(w) & 0xFF;

    if (!str_independent(str))
	str_make_independent(str);
    enc = STR_ENC_GET(str);
    head = RSTRING_PTR(str);
    ptr = (unsigned char *)&head[pos];
    if (!STR_EMBED_P(str)) {
	cr = ENC_CODERANGE(str);
	switch (cr) {
	  case ENC_CODERANGE_7BIT:
            left = (char *)ptr;
	    *ptr = byte;
	    if (ISASCII(byte)) goto end;
	    nlen = rb_enc_precise_mbclen(left, head+len, enc);
	    if (!MBCLEN_CHARFOUND_P(nlen))
		ENC_CODERANGE_SET(str, ENC_CODERANGE_BROKEN);
	    else
		ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
	    goto end;
	  case ENC_CODERANGE_VALID:
	    left = rb_enc_left_char_head(head, ptr, head+len, enc);
	    width = rb_enc_precise_mbclen(left, head+len, enc);
	    *ptr = byte;
	    nlen = rb_enc_precise_mbclen(left, head+len, enc);
	    if (!MBCLEN_CHARFOUND_P(nlen))
		ENC_CODERANGE_SET(str, ENC_CODERANGE_BROKEN);
	    else if (MBCLEN_CHARFOUND_LEN(nlen) != width || ISASCII(byte))
		ENC_CODERANGE_CLEAR(str);
	    goto end;
	}
    }
    ENC_CODERANGE_CLEAR(str);
    *ptr = byte;

  end:
    return value;
}

#length ⇒ `Integer`

Returns the count of characters (not bytes) in self:

"\x80\u3042".length # => 2
"hello".length # => 5

String#size is an alias for String#length.

Related: String#bytesize.

Returns:

(Integer)

# File 'string.c', line 1969

VALUE
rb_str_length(VALUE str)
{
    return LONG2NUM(str_strlen(str, NULL));
}

#[](index) ⇒ `nil` #[](start, length) ⇒ `nil` #[](range) ⇒ `nil` #[](regexp, capture = 0) ⇒ `nil` #[](substring) ⇒ `nil`

Returns the substring of self specified by the arguments.

When the single Integer argument index is given, returns the 1-character substring found in self at offset index:

'bar'[2] # => "r"

Counts backward from the end of self if index is negative:

'foo'[-3] # => "f"

Returns nil if index is out of range:

'foo'[3] # => nil
'foo'[-4] # => nil

When the two Integer arguments start and length are given, returns the substring of the given length found in self at offset start:

'foo'[0, 2] # => "fo"
'foo'[0, 0] # => ""

Counts backward from the end of self if start is negative:

'foo'[-2, 2] # => "oo"

Special case: returns a new empty String if start is equal to the length of self:

'foo'[3, 2] # => ""

Returns nil if start is out of range:

'foo'[4, 2] # => nil
'foo'[-4, 2] # => nil

Returns the trailing substring of self if length is large:

'foo'[1, 50] # => "oo"

Returns nil if length is negative:

'foo'[0, -1] # => nil

When the single Range argument range is given, derives start and length values from the given range, and returns values as above:

'foo'[0..1] is equivalent to 'foo'[0, 2].
'foo'[0...1] is equivalent to 'foo'[0, 1].

When the Regexp argument regexp is given, and the capture argument is 0, returns the first matching substring found in self, or nil if none found:

'foo'[/o/] # => "o"
'foo'[/x/] # => nil
s = 'hello there'
s[/[aeiou](.)\1/] # => "ell"
s[/[aeiou](.)\1/, 0] # => "ell"

s = 'hello there'
s[/[aeiou](.)\1/, 1] # => "l"
s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, "non_vowel"] # => "l"
s[/(?<vowel>[aeiou])(?<non_vowel>[^aeiou])/, :vowel] # => "e"

If an invalid capture group index is given, nil is returned. If an invalid capture group name is given, IndexError is raised.

When the single String argument substring is given, returns the substring from self if found, otherwise nil:

'foo'['oo'] # => "oo"
'foo'['xx'] # => nil

String#slice is an alias for String#[].

Overloads:

#[](index) ⇒ nil
Returns:
- (nil)
#[](start, length) ⇒ nil
Returns:
- (nil)
#[](range) ⇒ nil
Returns:
- (nil)
#[](regexp, capture = 0) ⇒ nil
Returns:
- (nil)
#[](substring) ⇒ nil
Returns:
- (nil)

# File 'string.c', line 4735

static VALUE
rb_str_aref_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
	if (RB_TYPE_P(argv[0], T_REGEXP)) {
	    return rb_str_subpat(str, argv[0], argv[1]);
	}
	else {
	    long beg = NUM2LONG(argv[0]);
	    long len = NUM2LONG(argv[1]);
	    return rb_str_substr(str, beg, len);
	}
    }
    rb_check_arity(argc, 1, 2);
    return rb_str_aref(str, argv[0]);
}

#slice!(integer) ⇒ `String`^? #slice!(integer, integer) ⇒ `String`^? #slice!(range) ⇒ `String`^? #slice!(regexp) ⇒ `String`^? #slice!(other_str) ⇒ `String`^?

Deletes the specified portion from str, and returns the portion deleted.

string = "this is a string"
string.slice!(2)        #=> "i"
string.slice!(3..6)     #=> " is "
string.slice!(/s.*t/)   #=> "sa st"
string.slice!("r")      #=> "r"
string                  #=> "thing"

Overloads:

#slice!(integer) ⇒ String^?
Returns:
- (String, nil)
#slice!(integer, integer) ⇒ String^?
Returns:
- (String, nil)
#slice!(range) ⇒ String^?
Returns:
- (String, nil)
#slice!(regexp) ⇒ String^?
Returns:
- (String, nil)
#slice!(other_str) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 5026

static VALUE
rb_str_slice_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE result = Qnil;
    VALUE indx;
    long beg, len = 1;
    char *p;

    rb_check_arity(argc, 1, 2);
    str_modify_keep_cr(str);
    indx = argv[0];
    if (RB_TYPE_P(indx, T_REGEXP)) {
	if (rb_reg_search(indx, str, 0, 0) < 0) return Qnil;
	VALUE match = rb_backref_get();
	struct re_registers *regs = RMATCH_REGS(match);
	int nth = 0;
	if (argc > 1 && (nth = rb_reg_backref_number(match, argv[1])) < 0) {
	    if ((nth += regs->num_regs) <= 0) return Qnil;
	}
	else if (nth >= regs->num_regs) return Qnil;
	beg = BEG(nth);
	len = END(nth) - beg;
        goto subseq;
    }
    else if (argc == 2) {
	beg = NUM2LONG(indx);
	len = NUM2LONG(argv[1]);
        goto num_index;
    }
    else if (FIXNUM_P(indx)) {
	beg = FIX2LONG(indx);
	if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
	if (!len) return Qnil;
	beg = p - RSTRING_PTR(str);
	goto subseq;
    }
    else if (RB_TYPE_P(indx, T_STRING)) {
	beg = rb_str_index(str, indx, 0);
	if (beg == -1) return Qnil;
	len = RSTRING_LEN(indx);
        result = str_duplicate(rb_cString, indx);
        goto squash;
    }
    else {
	switch (rb_range_beg_len(indx, &beg, &len, str_strlen(str, NULL), 0)) {
	  case Qnil:
	    return Qnil;
	  case Qfalse:
	    beg = NUM2LONG(indx);
	    if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
	    if (!len) return Qnil;
	    beg = p - RSTRING_PTR(str);
	    goto subseq;
	  default:
	    goto num_index;
	}
    }

  num_index:
    if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
    beg = p - RSTRING_PTR(str);

  subseq:
    result = rb_str_new(RSTRING_PTR(str)+beg, len);
    rb_enc_cr_str_copy_for_substr(result, str);

  squash:
    if (len > 0) {
	if (beg == 0) {
	    rb_str_drop_bytes(str, len);
	}
	else {
	    char *sptr = RSTRING_PTR(str);
	    long slen = RSTRING_LEN(str);
	    if (beg + len > slen) /* pathological check */
		len = slen - beg;
	    memmove(sptr + beg,
		    sptr + beg + len,
		    slen - (beg + len));
	    slen -= len;
	    STR_SET_LEN(str, slen);
	    TERM_FILL(&sptr[slen], TERM_LEN(str));
	}
    }
    return result;
}

#split(pattern = nil, [limit]) ⇒ `Array` #split(pattern = nil, [limit]) {|sub| ... } ⇒ `String`

Divides str into substrings based on a delimiter, returning an array of these substrings.

If pattern is a String, then its contents are used as the delimiter when splitting str. If pattern is a single space, str is split on whitespace, with leading and trailing whitespace and runs of contiguous whitespace characters ignored.

If pattern is a Regexp, str is divided where the pattern matches. Whenever the pattern matches a zero-length string, str is split into individual characters. If pattern contains groups, the respective matches will be returned in the array as well.

If pattern is nil, the value of $; is used. If $; is nil (which is the default), str is split on whitespace as if ‘ ’ were specified.

If the limit parameter is omitted, trailing null fields are suppressed. If limit is a positive number, at most that number of split substrings will be returned (captured groups will be returned as well, but are not counted towards the limit). If limit is 1, the entire string is returned as the only entry in an array. If negative, there is no limit to the number of fields returned, and trailing null fields are not suppressed.

When the input str is empty an empty Array is returned as the string is considered to have no fields to split.

" now's  the time ".split       #=> ["now's", "the", "time"]
" now's  the time ".split(' ')  #=> ["now's", "the", "time"]
" now's  the time".split(/ /)   #=> ["", "now's", "", "the", "time"]
"1, 2.34,56, 7".split(%r{,\s*}) #=> ["1", "2.34", "56", "7"]
"hello".split(//)               #=> ["h", "e", "l", "l", "o"]
"hello".split(//, 3)            #=> ["h", "e", "llo"]
"hi mom".split(%r{\s*})         #=> ["h", "i", "m", "o", "m"]

"mellow yellow".split("ello")   #=> ["m", "w y", "w"]
"1,2,,3,4,,".split(',')         #=> ["1", "2", "", "3", "4"]
"1,2,,3,4,,".split(',', 4)      #=> ["1", "2", "", "3,4,,"]
"1,2,,3,4,,".split(',', -4)     #=> ["1", "2", "", "3", "4", "", ""]

"1:2:3".split(/(:)()()/, 2)     #=> ["1", ":", "", "", "2:3"]

"".split(',', -1)               #=> []

If a block is given, invoke the block with each split substring.

Overloads:

#split(pattern = nil, [limit]) ⇒ Array
Returns:
- (Array)
#split(pattern = nil, [limit]) {|sub| ... } ⇒ String
Yields:
- (sub)
Returns:
- (String)

# File 'string.c', line 8150

static VALUE
rb_str_split_m(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE spat;
    VALUE limit;
    split_type_t split_type;
    long beg, end, i = 0, empty_count = -1;
    int lim = 0;
    VALUE result, tmp;

    result = rb_block_given_p() ? Qfalse : Qnil;
    if (rb_scan_args(argc, argv, "02", &spat, &limit) == 2) {
	lim = NUM2INT(limit);
	if (lim <= 0) limit = Qnil;
	else if (lim == 1) {
	    if (RSTRING_LEN(str) == 0)
                return result ? rb_ary_new2(0) : str;
            tmp = str_duplicate(rb_cString, str);
	    if (!result) {
		rb_yield(tmp);
                return str;
	    }
	    return rb_ary_new3(1, tmp);
	}
	i = 1;
    }
    if (NIL_P(limit) && !lim) empty_count = 0;

    enc = STR_ENC_GET(str);
    split_type = SPLIT_TYPE_REGEXP;
    if (!NIL_P(spat)) {
	spat = get_pat_quoted(spat, 0);
    }
    else if (NIL_P(spat = rb_fs)) {
	split_type = SPLIT_TYPE_AWK;
    }
    else if (!(spat = rb_fs_check(spat))) {
	rb_raise(rb_eTypeError, "value of $; must be String or Regexp");
    }
    else {
        rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "$; is set to non-nil value");
    }
    if (split_type != SPLIT_TYPE_AWK) {
        switch (BUILTIN_TYPE(spat)) {
          case T_REGEXP:
            rb_reg_options(spat); /* check if uninitialized */
            tmp = RREGEXP_SRC(spat);
            split_type = literal_split_pattern(tmp, SPLIT_TYPE_REGEXP);
            if (split_type == SPLIT_TYPE_AWK) {
                spat = tmp;
                split_type = SPLIT_TYPE_STRING;
            }
            break;

          case T_STRING:
	    mustnot_broken(spat);
            split_type = literal_split_pattern(spat, SPLIT_TYPE_STRING);
            break;

          default:
            UNREACHABLE_RETURN(Qnil);
	}
    }

#define SPLIT_STR(beg, len) (empty_count = split_string(result, str, beg, len, empty_count))

    if (result) result = rb_ary_new();
    beg = 0;
    char *ptr = RSTRING_PTR(str);
    char *eptr = RSTRING_END(str);
    if (split_type == SPLIT_TYPE_AWK) {
	char *bptr = ptr;
	int skip = 1;
	unsigned int c;

	end = beg;
	if (is_ascii_string(str)) {
	    while (ptr < eptr) {
		c = (unsigned char)*ptr++;
		if (skip) {
		    if (ascii_isspace(c)) {
			beg = ptr - bptr;
		    }
		    else {
			end = ptr - bptr;
			skip = 0;
			if (!NIL_P(limit) && lim <= i) break;
		    }
		}
		else if (ascii_isspace(c)) {
		    SPLIT_STR(beg, end-beg);
		    skip = 1;
		    beg = ptr - bptr;
		    if (!NIL_P(limit)) ++i;
		}
		else {
		    end = ptr - bptr;
		}
	    }
	}
	else {
	    while (ptr < eptr) {
		int n;

		c = rb_enc_codepoint_len(ptr, eptr, &n, enc);
		ptr += n;
		if (skip) {
		    if (rb_isspace(c)) {
			beg = ptr - bptr;
		    }
		    else {
			end = ptr - bptr;
			skip = 0;
			if (!NIL_P(limit) && lim <= i) break;
		    }
		}
		else if (rb_isspace(c)) {
		    SPLIT_STR(beg, end-beg);
		    skip = 1;
		    beg = ptr - bptr;
		    if (!NIL_P(limit)) ++i;
		}
		else {
		    end = ptr - bptr;
		}
	    }
	}
    }
    else if (split_type == SPLIT_TYPE_STRING) {
	char *str_start = ptr;
	char *substr_start = ptr;
	char *sptr = RSTRING_PTR(spat);
	long slen = RSTRING_LEN(spat);

	mustnot_broken(str);
	enc = rb_enc_check(str, spat);
	while (ptr < eptr &&
	       (end = rb_memsearch(sptr, slen, ptr, eptr - ptr, enc)) >= 0) {
	    /* Check we are at the start of a char */
	    char *t = rb_enc_right_char_head(ptr, ptr + end, eptr, enc);
	    if (t != ptr + end) {
		ptr = t;
		continue;
	    }
	    SPLIT_STR(substr_start - str_start, (ptr+end) - substr_start);
	    ptr += end + slen;
	    substr_start = ptr;
	    if (!NIL_P(limit) && lim <= ++i) break;
	}
	beg = ptr - str_start;
    }
    else if (split_type == SPLIT_TYPE_CHARS) {
        char *str_start = ptr;
        int n;

        mustnot_broken(str);
        enc = rb_enc_get(str);
        while (ptr < eptr &&
               (n = rb_enc_precise_mbclen(ptr, eptr, enc)) > 0) {
            SPLIT_STR(ptr - str_start, n);
            ptr += n;
            if (!NIL_P(limit) && lim <= ++i) break;
        }
        beg = ptr - str_start;
    }
    else {
	long len = RSTRING_LEN(str);
	long start = beg;
	long idx;
	int last_null = 0;
	struct re_registers *regs;
        VALUE match = 0;

        for (; rb_reg_search(spat, str, start, 0) >= 0;
             (match ? (rb_match_unbusy(match), rb_backref_set(match)) : (void)0)) {
            match = rb_backref_get();
            if (!result) rb_match_busy(match);
            regs = RMATCH_REGS(match);
            end = BEG(0);
	    if (start == end && BEG(0) == END(0)) {
		if (!ptr) {
		    SPLIT_STR(0, 0);
		    break;
		}
		else if (last_null == 1) {
                    SPLIT_STR(beg, rb_enc_fast_mbclen(ptr+beg, eptr, enc));
		    beg = start;
		}
		else {
                    if (start == len)
                        start++;
                    else
                        start += rb_enc_fast_mbclen(ptr+start,eptr,enc);
		    last_null = 1;
		    continue;
		}
	    }
	    else {
		SPLIT_STR(beg, end-beg);
		beg = start = END(0);
	    }
	    last_null = 0;

	    for (idx=1; idx < regs->num_regs; idx++) {
		if (BEG(idx) == -1) continue;
		SPLIT_STR(BEG(idx), END(idx)-BEG(idx));
	    }
	    if (!NIL_P(limit) && lim <= ++i) break;
	}
        if (match) rb_match_unbusy(match);
    }
    if (RSTRING_LEN(str) > 0 && (!NIL_P(limit) || RSTRING_LEN(str) > beg || lim < 0)) {
	SPLIT_STR(beg, RSTRING_LEN(str)-beg);
    }

    return result ? result : str;
}

#squeeze([other_str]) ⇒ `String`

Builds a set of characters from the other_str parameter(s) using the procedure described for String#count. Returns a new string where runs of the same character that occur in this set are replaced by a single character. If no arguments are given, all runs of identical characters are replaced by a single character.

"yellow moon".squeeze                  #=> "yelow mon"
"  now   is  the".squeeze(" ")         #=> " now is the"
"putters shoot balls".squeeze("m-z")   #=> "puters shot balls"

Returns:

(String)

# File 'string.c', line 7863

static VALUE
rb_str_squeeze(int argc, VALUE *argv, VALUE str)
{
    str = str_duplicate(rb_cString, str);
    rb_str_squeeze_bang(argc, argv, str);
    return str;
}

#squeeze!([other_str]) ⇒ `String`^?

Squeezes str in place, returning either str, or nil if no changes were made.

Returns:

(String, nil)

# File 'string.c', line 7772

static VALUE
rb_str_squeeze_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0;
    unsigned char *s, *send, *t;
    int i, modify = 0;
    int ascompat, singlebyte = single_byte_optimizable(str);
    unsigned int save;

    if (argc == 0) {
	enc = STR_ENC_GET(str);
    }
    else {
	for (i=0; i<argc; i++) {
	    VALUE s = argv[i];

	    StringValue(s);
	    enc = rb_enc_check(str, s);
	    if (singlebyte && !single_byte_optimizable(s))
		singlebyte = 0;
	    tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
	}
    }

    str_modify_keep_cr(str);
    s = t = (unsigned char *)RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    send = (unsigned char *)RSTRING_END(str);
    save = -1;
    ascompat = rb_enc_asciicompat(enc);

    if (singlebyte) {
        while (s < send) {
            unsigned int c = *s++;
	    if (c != save || (argc > 0 && !squeez[c])) {
	        *t++ = save = c;
	    }
	}
    }
    else {
	while (s < send) {
	    unsigned int c;
	    int clen;

            if (ascompat && (c = *s) < 0x80) {
		if (c != save || (argc > 0 && !squeez[c])) {
		    *t++ = save = c;
		}
		s++;
	    }
	    else {
                c = rb_enc_codepoint_len((char *)s, (char *)send, &clen, enc);

		if (c != save || (argc > 0 && !tr_find(c, squeez, del, nodel))) {
		    if (t != s) rb_enc_mbcput(c, t, enc);
		    save = c;
		    t += clen;
		}
		s += clen;
	    }
	}
    }

    TERM_FILL((char *)t, TERM_LEN(str));
    if ((char *)t - RSTRING_PTR(str) != RSTRING_LEN(str)) {
        STR_SET_LEN(str, (char *)t - RSTRING_PTR(str));
	modify = 1;
    }

    if (modify) return str;
    return Qnil;
}

#start_with?([prefixes]) ⇒ `Boolean`

Returns true if str starts with one of the prefixes given. Each of the prefixes should be a String or a Regexp.

"hello".start_with?("hell")               #=> true
"hello".start_with?(/H/i)                 #=> true

# returns true if one of the prefixes matches.
"hello".start_with?("heaven", "hell")     #=> true
"hello".start_with?("heaven", "paradise") #=> false

Returns:

(Boolean)

# File 'string.c', line 10133

static VALUE
rb_str_start_with(int argc, VALUE *argv, VALUE str)
{
    int i;

    for (i=0; i<argc; i++) {
	VALUE tmp = argv[i];
	if (RB_TYPE_P(tmp, T_REGEXP)) {
	    if (rb_reg_start_with_p(tmp, str))
		return Qtrue;
	}
	else {
	    StringValue(tmp);
	    rb_enc_check(str, tmp);
	    if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
	    if (memcmp(RSTRING_PTR(str), RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
		return Qtrue;
	}
    }
    return Qfalse;
}

#strip ⇒ `String`

Returns a copy of the receiver with leading and trailing whitespace removed.

Whitespace is defined as any of the following characters: null, horizontal tab, line feed, vertical tab, form feed, carriage return, space.

"    hello    ".strip   #=> "hello"
"\tgoodbye\r\n".strip   #=> "goodbye"
"\x00\t\n\v\f\r ".strip #=> ""
"hello".strip           #=> "hello"

Returns:

(String)

# File 'string.c', line 9497

static VALUE
rb_str_strip(VALUE str)
{
    char *start;
    long olen, loffset, roffset;
    rb_encoding *enc = STR_ENC_GET(str);

    RSTRING_GETMEM(str, start, olen);
    loffset = lstrip_offset(str, start, start+olen, enc);
    roffset = rstrip_offset(str, start+loffset, start+olen, enc);

    if (loffset <= 0 && roffset <= 0) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, loffset, olen-loffset-roffset);
}

#strip! ⇒ `self`^?

Removes leading and trailing whitespace from the receiver. Returns the altered receiver, or nil if there was no change.

Refer to String#strip for the definition of whitespace.

"  hello  ".strip!  #=> "hello"
"hello".strip!      #=> nil

Returns:

(self, nil)

# File 'string.c', line 9453

static VALUE
rb_str_strip_bang(VALUE str)
{
    char *start;
    long olen, loffset, roffset;
    rb_encoding *enc;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    loffset = lstrip_offset(str, start, start+olen, enc);
    roffset = rstrip_offset(str, start+loffset, start+olen, enc);

    if (loffset > 0 || roffset > 0) {
	long len = olen-roffset;
	if (loffset > 0) {
	    len -= loffset;
	    memmove(start, start + loffset, len);
	}
	STR_SET_LEN(str, len);
#if !SHARABLE_MIDDLE_SUBSTRING
	TERM_FILL(start+len, rb_enc_mbminlen(enc));
#endif
	return str;
    }
    return Qnil;
}

#sub(pattern, replacement) ⇒ `String` #sub(pattern, hash) ⇒ `String` #sub(pattern) {|match| ... } ⇒ `String`

Returns a copy of str with the first occurrence of pattern replaced by the second argument. The pattern is typically a Regexp; if given as a String, any regular expression metacharacters it contains will be interpreted literally, e.g. \d will match a backslash followed by ‘d’, instead of a digit.

If the second argument is a Hash, and the matched text is one of its keys, the corresponding value is the replacement string.

"hello".sub(/[aeiou]/, '*')                  #=> "h*llo"
"hello".sub(/([aeiou])/, '<\1>')             #=> "h<e>llo"
"hello".sub(/./) {|s| s.ord.to_s + ' ' }     #=> "104 ello"
"hello".sub(/(?<foo>[aeiou])/, '*\k<foo>*')  #=> "h*e*llo"
'Is SHELL your preferred shell?'.sub(/[[:upper:]]{2,}/, ENV)
 #=> "Is /bin/bash your preferred shell?"

Note that a string literal consumes backslashes. (See syntax/literals.rdoc for details about string literals.) Back-references are typically preceded by an additional backslash. For example, if you want to write a back-reference \& in replacement with a double-quoted string literal, you need to write: "..\\&..". If you want to write a non-back-reference string \& in replacement, you need first to escape the backslash to prevent this method from interpreting it as a back-reference, and then you need to escape the backslashes again to prevent a string literal from consuming them: "..\\\\&..". You may want to use the block form to avoid a lot of backslashes.

Overloads:

#sub(pattern, replacement) ⇒ String
Returns:
- (String)
#sub(pattern, hash) ⇒ String
Returns:
- (String)
#sub(pattern) {|match| ... } ⇒ String
Yields:
- (match)
Returns:
- (String)

# File 'string.c', line 5359

static VALUE
rb_str_sub(int argc, VALUE *argv, VALUE str)
{
    str = str_duplicate(rb_cString, str);
    rb_str_sub_bang(argc, argv, str);
    return str;
}

#sub!(pattern, replacement) ⇒ `String`^? #sub!(pattern) {|match| ... } ⇒ `String`^?

Performs the same substitution as String#sub in-place.

Returns str if a substitution was performed or nil if no substitution was performed.

Overloads:

#sub!(pattern, replacement) ⇒ String^?
Returns:
- (String, nil)
#sub!(pattern) {|match| ... } ⇒ String^?
Yields:
- (match)
Returns:
- (String, nil)

# File 'string.c', line 5194

static VALUE
rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE pat, repl, hash = Qnil;
    int iter = 0;
    long plen;
    int min_arity = rb_block_given_p() ? 1 : 2;
    long beg;

    rb_check_arity(argc, min_arity, 2);
    if (argc == 1) {
	iter = 1;
    }
    else {
	repl = argv[1];
	hash = rb_check_hash_type(argv[1]);
	if (NIL_P(hash)) {
	    StringValue(repl);
	}
    }

    pat = get_pat_quoted(argv[0], 1);

    str_modifiable(str);
    beg = rb_pat_search(pat, str, 0, 1);
    if (beg >= 0) {
	rb_encoding *enc;
	int cr = ENC_CODERANGE(str);
	long beg0, end0;
	VALUE match, match0 = Qnil;
	struct re_registers *regs;
	char *p, *rp;
	long len, rlen;

	match = rb_backref_get();
	regs = RMATCH_REGS(match);
	if (RB_TYPE_P(pat, T_STRING)) {
	    beg0 = beg;
	    end0 = beg0 + RSTRING_LEN(pat);
	    match0 = pat;
	}
	else {
	    beg0 = BEG(0);
	    end0 = END(0);
	    if (iter) match0 = rb_reg_nth_match(0, match);
	}

	if (iter || !NIL_P(hash)) {
	    p = RSTRING_PTR(str); len = RSTRING_LEN(str);

            if (iter) {
                repl = rb_obj_as_string(rb_yield(match0));
            }
            else {
                repl = rb_hash_aref(hash, rb_str_subseq(str, beg0, end0 - beg0));
                repl = rb_obj_as_string(repl);
            }
	    str_mod_check(str, p, len);
	    rb_check_frozen(str);
	}
	else {
	    repl = rb_reg_regsub(repl, str, regs, RB_TYPE_P(pat, T_STRING) ? Qnil : pat);
	}

        enc = rb_enc_compatible(str, repl);
        if (!enc) {
            rb_encoding *str_enc = STR_ENC_GET(str);
	    p = RSTRING_PTR(str); len = RSTRING_LEN(str);
	    if (coderange_scan(p, beg0, str_enc) != ENC_CODERANGE_7BIT ||
		coderange_scan(p+end0, len-end0, str_enc) != ENC_CODERANGE_7BIT) {
                rb_raise(rb_eEncCompatError, "incompatible character encodings: %s and %s",
			 rb_enc_name(str_enc),
			 rb_enc_name(STR_ENC_GET(repl)));
            }
            enc = STR_ENC_GET(repl);
        }
	rb_str_modify(str);
	rb_enc_associate(str, enc);
	if (ENC_CODERANGE_UNKNOWN < cr && cr < ENC_CODERANGE_BROKEN) {
	    int cr2 = ENC_CODERANGE(repl);
            if (cr2 == ENC_CODERANGE_BROKEN ||
                (cr == ENC_CODERANGE_VALID && cr2 == ENC_CODERANGE_7BIT))
                cr = ENC_CODERANGE_UNKNOWN;
            else
                cr = cr2;
	}
	plen = end0 - beg0;
        rlen = RSTRING_LEN(repl);
	len = RSTRING_LEN(str);
	if (rlen > plen) {
	    RESIZE_CAPA(str, len + rlen - plen);
	}
	p = RSTRING_PTR(str);
	if (rlen != plen) {
	    memmove(p + beg0 + rlen, p + beg0 + plen, len - beg0 - plen);
	}
        rp = RSTRING_PTR(repl);
        memmove(p + beg0, rp, rlen);
	len += rlen - plen;
	STR_SET_LEN(str, len);
	TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
	ENC_CODERANGE_SET(str, cr);

	return str;
    }
    return Qnil;
}

#succ ⇒ `String`

Returns the successor to self. The successor is calculated by incrementing characters.

The first character to be incremented is the rightmost alphanumeric: or, if no alphanumerics, the rightmost character:

'THX1138'.succ # => "THX1139"
'<<koala>>'.succ # => "<<koalb>>"
'***'.succ # => '**+'

The successor to a digit is another digit, “carrying” to the next-left character for a “rollover” from 9 to 0, and prepending another digit if necessary:

'00'.succ # => "01"
'09'.succ # => "10"
'99'.succ # => "100"

The successor to a letter is another letter of the same case, carrying to the next-left character for a rollover, and prepending another same-case letter if necessary:

'aa'.succ # => "ab"
'az'.succ # => "ba"
'zz'.succ # => "aaa"
'AA'.succ # => "AB"
'AZ'.succ # => "BA"
'ZZ'.succ # => "AAA"

s = 0.chr * 3
s # => "\x00\x00\x00"
s.succ # => "\x00\x00\x01"
s = 255.chr * 3
s # => "\xFF\xFF\xFF"
s.succ # => "\x01\x00\x00\x00"

Carrying can occur between and among mixtures of alphanumeric characters:

s = 'zz99zz99'
s.succ # => "aaa00aa00"
s = '99zz99zz'
s.succ # => "100aa00aa"

The successor to an empty String is a new empty String:

''.succ # => ""

String#next is an alias for String#succ.

Returns:

(String)

# File 'string.c', line 4272

VALUE
rb_str_succ(VALUE orig)
{
    VALUE str;
    str = rb_str_new(RSTRING_PTR(orig), RSTRING_LEN(orig));
    rb_enc_cr_str_copy_for_substr(str, orig);
    return str_succ(str);
}

#succ! ⇒ `self`

Equivalent to String#succ, but modifies self in place; returns self.

String#next! is an alias for String#succ!.

Returns:

(self)

# File 'string.c', line 4378

static VALUE
rb_str_succ_bang(VALUE str)
{
    rb_str_modify(str);
    str_succ(str);
    return str;
}

#sum(n = 16) ⇒ `Integer`

Returns a basic n-bit checksum of the characters in str, where n is the optional Integer parameter, defaulting to 16. The result is simply the sum of the binary value of each byte in str modulo 2**n - 1. This is not a particularly good checksum.

Returns:

(Integer)

# File 'string.c', line 9821

static VALUE
rb_str_sum(int argc, VALUE *argv, VALUE str)
{
    int bits = 16;
    char *ptr, *p, *pend;
    long len;
    VALUE sum = INT2FIX(0);
    unsigned long sum0 = 0;

    if (rb_check_arity(argc, 0, 1) && (bits = NUM2INT(argv[0])) < 0) {
        bits = 0;
    }
    ptr = p = RSTRING_PTR(str);
    len = RSTRING_LEN(str);
    pend = p + len;

    while (p < pend) {
        if (FIXNUM_MAX - UCHAR_MAX < sum0) {
            sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            str_mod_check(str, ptr, len);
            sum0 = 0;
        }
        sum0 += (unsigned char)*p;
        p++;
    }

    if (bits == 0) {
        if (sum0) {
            sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
        }
    }
    else {
        if (sum == INT2FIX(0)) {
            if (bits < (int)sizeof(long)*CHAR_BIT) {
                sum0 &= (((unsigned long)1)<<bits)-1;
            }
            sum = LONG2FIX(sum0);
        }
        else {
            VALUE mod;

            if (sum0) {
                sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            }

            mod = rb_funcall(INT2FIX(1), idLTLT, 1, INT2FIX(bits));
            mod = rb_funcall(mod, '-', 1, INT2FIX(1));
            sum = rb_funcall(sum, '&', 1, mod);
        }
    }
    return sum;
}

#swapcase ⇒ `String` #swapcase([options]) ⇒ `String`

Returns a copy of str with uppercase alphabetic characters converted to lowercase and lowercase characters converted to uppercase.

See String#downcase for meaning of options and use with different encodings.

"Hello".swapcase          #=> "hELLO"
"cYbEr_PuNk11".swapcase   #=> "CyBeR_pUnK11"

Overloads:

#swapcase ⇒ String
Returns:
- (String)
#swapcase([options]) ⇒ String
Returns:
- (String)

# File 'string.c', line 7193

static VALUE
rb_str_swapcase(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_DOWNCASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return str_duplicate(rb_cString, str);
    if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }
    return ret;
}

#swapcase! ⇒ `String`^? #swapcase!([options]) ⇒ `String`^?

Equivalent to String#swapcase, but modifies the receiver in place, returning str, or nil if no changes were made.

See String#downcase for meaning of options and use with different encodings.

Overloads:

#swapcase! ⇒ String^?
Returns:
- (String, nil)
#swapcase!([options]) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 7160

static VALUE
rb_str_swapcase_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_DOWNCASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
	str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#to_c ⇒ `Object`

Returns a complex which denotes the string form. The parser ignores leading whitespaces and trailing garbage. Any digit sequences can be separated by an underscore. Returns zero for null or garbage string.

'9'.to_c           #=> (9+0i)
'2.5'.to_c         #=> (2.5+0i)
'2.5/1'.to_c       #=> ((5/2)+0i)
'-3/2'.to_c        #=> ((-3/2)+0i)
'-i'.to_c          #=> (0-1i)
'45i'.to_c         #=> (0+45i)
'3-4i'.to_c        #=> (3-4i)
'-4e2-4e-2i'.to_c  #=> (-400.0-0.04i)
'-0.0-0.0i'.to_c   #=> (-0.0-0.0i)
'1/2+3/4i'.to_c    #=> ((1/2)+(3/4)*i)
'ruby'.to_c        #=> (0+0i)

See Kernel.Complex.

# File 'complex.c', line 2038

static VALUE
string_to_c(VALUE self)
{
    char *s;
    VALUE num;

    rb_must_asciicompat(self);

    s = RSTRING_PTR(self);

    if (s && s[RSTRING_LEN(self)]) {
	rb_str_modify(self);
	s = RSTRING_PTR(self);
	s[RSTRING_LEN(self)] = '\0';
    }

    if (!s)
	s = (char *)"";

    (void)parse_comp(s, 0, &num);

    return num;
}

#to_f ⇒ `Float`

Returns the result of interpreting leading characters in str as a floating point number. Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of str, 0.0 is returned. This method never raises an exception.

"123.45e1".to_f        #=> 1234.5
"45.67 degrees".to_f   #=> 45.67
"thx1138".to_f         #=> 0.0

Returns:

(Float)

# File 'string.c', line 6001

static VALUE
rb_str_to_f(VALUE str)
{
    return DBL2NUM(rb_str_to_dbl(str, FALSE));
}

#to_i(base = 10) ⇒ `Integer`

Returns the result of interpreting leading characters in str as an integer base base (between 2 and 36). Extraneous characters past the end of a valid number are ignored. If there is not a valid number at the start of str, 0 is returned. This method never raises an exception when base is valid.

"12345".to_i             #=> 12345
"99 red balloons".to_i   #=> 99
"0a".to_i                #=> 0
"0a".to_i(16)            #=> 10
"hello".to_i             #=> 0
"1100101".to_i(2)        #=> 101
"1100101".to_i(8)        #=> 294977
"1100101".to_i(10)       #=> 1100101
"1100101".to_i(16)       #=> 17826049

Returns:

(Integer)

# File 'string.c', line 5975

static VALUE
rb_str_to_i(int argc, VALUE *argv, VALUE str)
{
    int base = 10;

    if (rb_check_arity(argc, 0, 1) && (base = NUM2INT(argv[0])) < 0) {
	rb_raise(rb_eArgError, "invalid radix %d", base);
    }
    return rb_str_to_inum(str, base, FALSE);
}

#to_r ⇒ `Object`

Returns the result of interpreting leading characters in str as a rational. Leading whitespace and extraneous characters past the end of a valid number are ignored. Digit sequences can be separated by an underscore. If there is not a valid number at the start of str, zero is returned. This method never raises an exception.

'  2  '.to_r       #=> (2/1)
'300/2'.to_r       #=> (150/1)
'-9.2'.to_r        #=> (-46/5)
'-9.2e2'.to_r      #=> (-920/1)
'1_234_567'.to_r   #=> (1234567/1)
'21 June 09'.to_r  #=> (21/1)
'21/06/09'.to_r    #=> (7/2)
'BWV 1079'.to_r    #=> (0/1)

NOTE: “0.3”.to_r isn’t the same as 0.3.to_r. The former is equivalent to “3/10”.to_r, but the latter isn’t so.

"0.3".to_r == 3/10r  #=> true
0.3.to_r   == 3/10r  #=> false

#to_s ⇒ `String` #to_str ⇒ `String`

Returns self.

If called on a subclass of String, converts the receiver to a String object.

Overloads:

#to_s ⇒ String
Returns:
- (String)
#to_str ⇒ String
Returns:
- (String)

# File 'string.c', line 6018

static VALUE
rb_str_to_s(VALUE str)
{
    if (rb_obj_class(str) != rb_cString) {
	return str_duplicate(rb_cString, str);
    }
    return str;
}

#to_s ⇒ `String` #to_str ⇒ `String`

Returns self.

If called on a subclass of String, converts the receiver to a String object.

Overloads:

#to_s ⇒ String
Returns:
- (String)
#to_str ⇒ String
Returns:
- (String)

# File 'string.c', line 6018

static VALUE
rb_str_to_s(VALUE str)
{
    if (rb_obj_class(str) != rb_cString) {
	return str_duplicate(rb_cString, str);
    }
    return str;
}

#intern ⇒ `Object` #to_sym ⇒ `Object`

Returns the Symbol corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name.

"Koala".intern         #=> :Koala
s = 'cat'.to_sym       #=> :cat
s == :cat              #=> true
s = '@cat'.to_sym      #=> :@cat
s == :@cat             #=> true

This can also be used to create symbols that cannot be represented using the :xxx notation.

'cat and dog'.to_sym   #=> :"cat and dog"

# File 'symbol.c', line 839

VALUE
rb_str_intern(VALUE str)
{
    VALUE sym;
#if USE_SYMBOL_GC
    rb_encoding *enc, *ascii;
    int type;
#else
    ID id;
#endif
    GLOBAL_SYMBOLS_ENTER(symbols);
    {
        sym = lookup_str_sym_with_lock(symbols, str);

        if (sym) {
            // ok
        }
        else {
#if USE_SYMBOL_GC
            enc = rb_enc_get(str);
            ascii = rb_usascii_encoding();
            if (enc != ascii && sym_check_asciionly(str)) {
                str = rb_str_dup(str);
                rb_enc_associate(str, ascii);
                OBJ_FREEZE(str);
                enc = ascii;
            }
            else {
                str = rb_str_dup(str);
                OBJ_FREEZE(str);
            }
            str = rb_fstring(str);
            type = rb_str_symname_type(str, IDSET_ATTRSET_FOR_INTERN);
            if (type < 0) type = ID_JUNK;
            sym = dsymbol_alloc(symbols, rb_cSymbol, str, enc, type);
#else
            id = intern_str(str, 0);
            sym = ID2SYM(id);
#endif
        }
    }
    GLOBAL_SYMBOLS_LEAVE();
    return sym;
}

#tr(from_str, to_str) ⇒ `String`

Returns a copy of str with the characters in from_str replaced by the corresponding characters in to_str. If to_str is shorter than from_str, it is padded with its last character in order to maintain the correspondence.

"hello".tr('el', 'ip')      #=> "hippo"
"hello".tr('aeiou', '*')    #=> "h*ll*"
"hello".tr('aeiou', 'AA*')  #=> "hAll*"

Both strings may use the c1-c2 notation to denote ranges of characters, and from_str may start with a ^, which denotes all characters except those listed.

"hello".tr('a-y', 'b-z')    #=> "ifmmp"
"hello".tr('^aeiou', '*')   #=> "*e**o"

The backslash character \ can be used to escape ^ or - and is otherwise ignored unless it appears at the end of a range or the end of the from_str or to_str:

"hello^world".tr("\\^aeiou", "*") #=> "h*ll**w*rld"
"hello-world".tr("a\\-eo", "*")   #=> "h*ll**w*rld"

"hello\r\nworld".tr("\r", "")   #=> "hello\nworld"
"hello\r\nworld".tr("\\r", "")  #=> "hello\r\nwold"
"hello\r\nworld".tr("\\\r", "") #=> "hello\nworld"

"X['\\b']".tr("X\\", "")   #=> "['b']"
"X['\\b']".tr("X-\\]", "") #=> "'b'"

Returns:

(String)

# File 'string.c', line 7575

static VALUE
rb_str_tr(VALUE str, VALUE src, VALUE repl)
{
    str = str_duplicate(rb_cString, str);
    tr_trans(str, src, repl, 0);
    return str;
}

#tr!(from_str, to_str) ⇒ `String`^?

Translates str in place, using the same rules as String#tr. Returns str, or nil if no changes were made.

Returns:

(String, nil)

# File 'string.c', line 7533

static VALUE
rb_str_tr_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 0);
}

#tr_s(from_str, to_str) ⇒ `String`

Processes a copy of str as described under String#tr, then removes duplicate characters in regions that were affected by the translation.

"hello".tr_s('l', 'r')     #=> "hero"
"hello".tr_s('el', '*')    #=> "h*o"
"hello".tr_s('el', 'hx')   #=> "hhxo"

Returns:

(String)

# File 'string.c', line 7900

static VALUE
rb_str_tr_s(VALUE str, VALUE src, VALUE repl)
{
    str = str_duplicate(rb_cString, str);
    tr_trans(str, src, repl, 1);
    return str;
}

#tr_s!(from_str, to_str) ⇒ `String`^?

Performs String#tr_s processing on str in place, returning str, or nil if no changes were made.

Returns:

(String, nil)

# File 'string.c', line 7880

static VALUE
rb_str_tr_s_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 1);
}

#undump ⇒ `String`

Returns an unescaped version of the string. This does the inverse of String#dump.

"\"hello \\n ''\"".undump #=> "hello \n ''"

Returns:

(String)

# File 'string.c', line 6558

static VALUE
str_undump(VALUE str)
{
    const char *s = RSTRING_PTR(str);
    const char *s_end = RSTRING_END(str);
    rb_encoding *enc = rb_enc_get(str);
    VALUE undumped = rb_enc_str_new(s, 0L, enc);
    bool utf8 = false;
    bool binary = false;
    int w;

    rb_must_asciicompat(str);
    if (rb_str_is_ascii_only_p(str) == Qfalse) {
	rb_raise(rb_eRuntimeError, "non-ASCII character detected");
    }
    if (!str_null_check(str, &w)) {
	rb_raise(rb_eRuntimeError, "string contains null byte");
    }
    if (RSTRING_LEN(str) < 2) goto invalid_format;
    if (*s != '"') goto invalid_format;

    /* strip '"' at the start */
    s++;

    for (;;) {
	if (s >= s_end) {
	    rb_raise(rb_eRuntimeError, "unterminated dumped string");
	}

	if (*s == '"') {
	    /* epilogue */
	    s++;
	    if (s == s_end) {
		/* ascii compatible dumped string */
		break;
	    }
	    else {
		static const char force_encoding_suffix[] = ".force_encoding(\""; /* "\")" */
		static const char dup_suffix[] = ".dup";
		const char *encname;
		int encidx;
		ptrdiff_t size;

		/* check separately for strings dumped by older versions */
		size = sizeof(dup_suffix) - 1;
		if (s_end - s > size && memcmp(s, dup_suffix, size) == 0) s += size;

		size = sizeof(force_encoding_suffix) - 1;
		if (s_end - s <= size) goto invalid_format;
		if (memcmp(s, force_encoding_suffix, size) != 0) goto invalid_format;
		s += size;

		if (utf8) {
		    rb_raise(rb_eRuntimeError, "dumped string contained Unicode escape but used force_encoding");
		}

		encname = s;
		s = memchr(s, '"', s_end-s);
		size = s - encname;
		if (!s) goto invalid_format;
		if (s_end - s != 2) goto invalid_format;
		if (s[0] != '"' || s[1] != ')') goto invalid_format;

		encidx = rb_enc_find_index2(encname, (long)size);
		if (encidx < 0) {
		    rb_raise(rb_eRuntimeError, "dumped string has unknown encoding name");
		}
		rb_enc_associate_index(undumped, encidx);
	    }
	    break;
	}

	if (*s == '\\') {
	    s++;
	    if (s >= s_end) {
		rb_raise(rb_eRuntimeError, "invalid escape");
	    }
	    undump_after_backslash(undumped, &s, s_end, &enc, &utf8, &binary);
	}
	else {
	    rb_str_cat(undumped, s++, 1);
	}
    }

    return undumped;
invalid_format:
    rb_raise(rb_eRuntimeError, "invalid dumped string; not wrapped with '\"' nor '\"...\".force_encoding(\"...\")' form");
}

#unicode_normalize(form = :nfc) ⇒ `Object`

Unicode Normalization—Returns a normalized form of str, using Unicode normalizations NFC, NFD, NFKC, or NFKD. The normalization form used is determined by form, which can be any of the four values :nfc, :nfd, :nfkc, or :nfkd. The default is :nfc.

If the string is not in a Unicode Encoding, then an Exception is raised. In this context, ‘Unicode Encoding’ means any of UTF-8, UTF-16BE/LE, and UTF-32BE/LE, as well as GB18030, UCS_2BE, and UCS_4BE. Anything other than UTF-8 is implemented by converting to UTF-8, which makes it slower than UTF-8.

"a\u0300".unicode_normalize        #=> "\u00E0"
"a\u0300".unicode_normalize(:nfc)  #=> "\u00E0"
"\u00E0".unicode_normalize(:nfd)   #=> "a\u0300"
"\xE0".force_encoding('ISO-8859-1').unicode_normalize(:nfd)
                                   #=> Encoding::CompatibilityError raised

# File 'string.c', line 10870

static VALUE
rb_str_unicode_normalize(int argc, VALUE *argv, VALUE str)
{
    return unicode_normalize_common(argc, argv, str, id_normalize);
}

#unicode_normalize!(form = :nfc) ⇒ `Object`

Destructive version of String#unicode_normalize, doing Unicode normalization in place.

# File 'string.c', line 10883

static VALUE
rb_str_unicode_normalize_bang(int argc, VALUE *argv, VALUE str)
{
    return rb_str_replace(str, unicode_normalize_common(argc, argv, str, id_normalize));
}

#unicode_normalized?(form = :nfc) ⇒ `Boolean`

Checks whether str is in Unicode normalization form form, which can be any of the four values :nfc, :nfd, :nfkc, or :nfkd. The default is :nfc.

If the string is not in a Unicode Encoding, then an Exception is raised. For details, see String#unicode_normalize.

"a\u0300".unicode_normalized?        #=> false
"a\u0300".unicode_normalized?(:nfd)  #=> true
"\u00E0".unicode_normalized?         #=> true
"\u00E0".unicode_normalized?(:nfd)   #=> false
"\xE0".force_encoding('ISO-8859-1').unicode_normalized?
                                     #=> Encoding::CompatibilityError raised

Returns:

(Boolean)

# File 'string.c', line 10906

static VALUE
rb_str_unicode_normalized_p(int argc, VALUE *argv, VALUE str)
{
    return unicode_normalize_common(argc, argv, str, id_normalized_p);
}

#upcase ⇒ `String` #upcase([options]) ⇒ `String`

Returns a copy of str with all lowercase letters replaced with their uppercase counterparts.

See String#downcase for meaning of options and use with different encodings.

"hEllO".upcase   #=> "HELLO"

Overloads:

#upcase ⇒ String
Returns:
- (String)
#upcase([options]) ⇒ String
Returns:
- (String)

# File 'string.c', line 6920

static VALUE
rb_str_upcase(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        ret = rb_str_new(RSTRING_PTR(str), RSTRING_LEN(str));
        str_enc_copy(ret, str);
        upcase_single(ret);
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }

    return ret;
}

#upcase! ⇒ `String`^? #upcase!([options]) ⇒ `String`^?

Upcases the contents of str, returning nil if no changes were made.

See String#downcase for meaning of options and use with different encodings.

Overloads:

#upcase! ⇒ String^?
Returns:
- (String, nil)
#upcase!([options]) ⇒ String^?
Returns:
- (String, nil)

# File 'string.c', line 6884

static VALUE
rb_str_upcase_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        if (upcase_single(str))
            flags |= ONIGENC_CASE_MODIFIED;
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
	str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#upto(other_string, exclusive = false) {|string| ... } ⇒ `self` #upto(other_string, exclusive = false) ⇒ `Object`

With a block given, calls the block with each String value returned by successive calls to String#succ; the first value is self, the next is self.succ, and so on; the sequence terminates when value other_string is reached; returns self:

'a8'.upto('b6') {|s| print s, ' ' } # => "a8"

Output:

a8 a9 b0 b1 b2 b3 b4 b5 b6

If argument exclusive is given as a truthy object, the last value is omitted:

'a8'.upto('b6', true) {|s| print s, ' ' } # => "a8"

Output:

a8 a9 b0 b1 b2 b3 b4 b5

If other_string would not be reached, does not call the block:

'25'.upto('5') {|s| fail s }
'aa'.upto('a') {|s| fail s }

With no block given, returns a new Enumerator:

'a8'.upto('b6') # => #<Enumerator: "a8":upto("b6")>

Overloads:

#upto(other_string, exclusive = false) {|string| ... } ⇒ self
Yields:
- (string)
Returns:
- (self)

# File 'string.c', line 4430

static VALUE
rb_str_upto(int argc, VALUE *argv, VALUE beg)
{
    VALUE end, exclusive;

    rb_scan_args(argc, argv, "11", &end, &exclusive);
    RETURN_ENUMERATOR(beg, argc, argv);
    return rb_str_upto_each(beg, end, RTEST(exclusive), str_upto_i, Qnil);
}

#valid_encoding? ⇒ `Boolean`

Returns true for a string which is encoded correctly.

"\xc2\xa1".force_encoding("UTF-8").valid_encoding?  #=> true
"\xc2".force_encoding("UTF-8").valid_encoding?      #=> false
"\x80".force_encoding("UTF-8").valid_encoding?      #=> false

Returns:

(Boolean)

# File 'string.c', line 10420

static VALUE
rb_str_valid_encoding_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return cr == ENC_CODERANGE_BROKEN ? Qfalse : Qtrue;
}

Class: String

Overview

Direct Known Subclasses

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Comparable

Constructor Details

#new(string = '') ⇒ Object #new(string = '', encoding: encoding) ⇒ Object #new(string = '', capacity: size) ⇒ Object

Class Method Details

.try_convert(object) ⇒ Object?

Instance Method Details

#%(object) ⇒ Object

#*(integer) ⇒ Object

#+(other_string) ⇒ Object

#+ ⇒ self

#- ⇒ Object

#<<(object) ⇒ String

#<=>(other_string) ⇒ -1, ...

#==(object) ⇒ Boolean #===(object) ⇒ Boolean

#==(object) ⇒ Boolean #===(object) ⇒ Boolean

#=~(regexp) ⇒ Integer? #=~(object) ⇒ Integer?

#[](index) ⇒ nil #[](start, length) ⇒ nil #[](range) ⇒ nil #[](regexp, capture = 0) ⇒ nil #[](substring) ⇒ nil

#[]=(integer) ⇒ Object #[]=(integer, integer) ⇒ Object #[]=(range) ⇒ Object #[]=(regexp) ⇒ Object #[]=(regexp, integer) ⇒ Object #[]=(regexp, name) ⇒ Object #[]=(other_str) ⇒ Object

#ascii_only? ⇒ Boolean

#b ⇒ String

#bytes ⇒ Array

#bytesize ⇒ Integer

#byteslice(integer) ⇒ String? #byteslice(integer, integer) ⇒ String? #byteslice(range) ⇒ String?

#capitalize ⇒ String #capitalize([options]) ⇒ String

#capitalize! ⇒ String? #capitalize!([options]) ⇒ String?

#casecmp(other_str) ⇒ -1, ...

#casecmp?(other_string) ⇒ true, ...

#center(width, padstr = ' ') ⇒ String

#chars ⇒ Array

#chomp(separator = $/) ⇒ String

#chomp!(separator = $/) ⇒ String?

#chop ⇒ String

#chop! ⇒ String?

#chr ⇒ String

#clear ⇒ String

#codepoints ⇒ Array

#concat(*objects) ⇒ Object

#count([other_str]) ⇒ Integer

#crypt(salt_str) ⇒ String

#delete([other_str]) ⇒ String

#delete!([other_str]) ⇒ String?

#delete_prefix(prefix) ⇒ String

#delete_prefix!(prefix) ⇒ self?

#delete_suffix(suffix) ⇒ String

#delete_suffix!(suffix) ⇒ self?

#downcase ⇒ String #downcase([options]) ⇒ String

#downcase! ⇒ String? #downcase!([options]) ⇒ String?

#dump ⇒ String

#each_byte {|integer| ... } ⇒ String #each_byte ⇒ Object

#each_char {|cstr| ... } ⇒ String #each_char ⇒ Object

#each_codepoint {|integer| ... } ⇒ String #each_codepoint ⇒ Object

#each_grapheme_cluster {|cstr| ... } ⇒ String #each_grapheme_cluster ⇒ Object

#each_line(separator = $/, chomp: false) {|substr| ... } ⇒ String #each_line(separator = $/, chomp: false) ⇒ Object

#empty? ⇒ Boolean

#encode(encoding, **options) ⇒ String #encode(dst_encoding, src_encoding, **options) ⇒ String #encode(**options) ⇒ String

#encode!(encoding, **options) ⇒ String #encode!(dst_encoding, src_encoding, **options) ⇒ String

#encoding ⇒ Encoding

#end_with?([suffixes]) ⇒ Boolean

#eql?(object) ⇒ Boolean

#force_encoding(encoding) ⇒ String

#freeze ⇒ Object

#getbyte(index) ⇒ 0 .. 255

#grapheme_clusters ⇒ Array

#gsub(pattern, replacement) ⇒ String #gsub(pattern, hash) ⇒ String #gsub(pattern) {|match| ... } ⇒ String #gsub(pattern) ⇒ Object

#gsub!(pattern, replacement) ⇒ String? #gsub!(pattern, hash) ⇒ String? #gsub!(pattern) {|match| ... } ⇒ String? #gsub!(pattern) ⇒ Object

#hash ⇒ Integer

#hex ⇒ Integer

#include?(other_str) ⇒ Boolean

#index(substring, offset = 0) ⇒ Integer? #index(regexp, offset = 0) ⇒ Integer?

#replace(other_str) ⇒ String

#insert(index, other_string) ⇒ self

#inspect ⇒ String

#intern ⇒ Object #to_sym ⇒ Object

#length ⇒ Integer

#lines(separator = $/, chomp: false) ⇒ Array

#new(string = '') ⇒ `Object` #new(string = '', encoding: encoding) ⇒ `Object` #new(string = '', capacity: size) ⇒ `Object`

.try_convert(object) ⇒ `Object`^?

#%(object) ⇒ `Object`

#*(integer) ⇒ `Object`

#+(other_string) ⇒ `Object`

#+ ⇒ `self`

#- ⇒ `Object`

#<<(object) ⇒ `String`

#<=>(other_string) ⇒ `-1`, ...

#==(object) ⇒ `Boolean` #===(object) ⇒ `Boolean`

#==(object) ⇒ `Boolean` #===(object) ⇒ `Boolean`

#=~(regexp) ⇒ `Integer`^? #=~(object) ⇒ `Integer`^?

#[](index) ⇒ `nil` #[](start, length) ⇒ `nil` #[](range) ⇒ `nil` #[](regexp, capture = 0) ⇒ `nil` #[](substring) ⇒ `nil`

#[]=(integer) ⇒ `Object` #[]=(integer, integer) ⇒ `Object` #[]=(range) ⇒ `Object` #[]=(regexp) ⇒ `Object` #[]=(regexp, integer) ⇒ `Object` #[]=(regexp, name) ⇒ `Object` #[]=(other_str) ⇒ `Object`

#ascii_only? ⇒ `Boolean`

#b ⇒ `String`

#bytes ⇒ `Array`

#bytesize ⇒ `Integer`

#byteslice(integer) ⇒ `String`^? #byteslice(integer, integer) ⇒ `String`^? #byteslice(range) ⇒ `String`^?

#capitalize ⇒ `String` #capitalize([options]) ⇒ `String`

#capitalize! ⇒ `String`^? #capitalize!([options]) ⇒ `String`^?

#casecmp(other_str) ⇒ `-1`, ...

#casecmp?(other_string) ⇒ `true`, ...

#center(width, padstr = ' ') ⇒ `String`

#chars ⇒ `Array`

#chomp(separator = $/) ⇒ `String`

#chomp!(separator = $/) ⇒ `String`^?

#chop ⇒ `String`

#chop! ⇒ `String`^?

#chr ⇒ `String`

#clear ⇒ `String`

#codepoints ⇒ `Array`

#concat(*objects) ⇒ `Object`

#count([other_str]) ⇒ `Integer`

#crypt(salt_str) ⇒ `String`

#delete([other_str]) ⇒ `String`

#delete!([other_str]) ⇒ `String`^?

#delete_prefix(prefix) ⇒ `String`

#delete_prefix!(prefix) ⇒ `self`^?

#delete_suffix(suffix) ⇒ `String`

#delete_suffix!(suffix) ⇒ `self`^?

#downcase ⇒ `String` #downcase([options]) ⇒ `String`

#downcase! ⇒ `String`^? #downcase!([options]) ⇒ `String`^?

#dump ⇒ `String`

#each_byte {|integer| ... } ⇒ `String` #each_byte ⇒ `Object`

#each_char {|cstr| ... } ⇒ `String` #each_char ⇒ `Object`

#each_codepoint {|integer| ... } ⇒ `String` #each_codepoint ⇒ `Object`

#each_grapheme_cluster {|cstr| ... } ⇒ `String` #each_grapheme_cluster ⇒ `Object`

#each_line(separator = $/, chomp: false) {|substr| ... } ⇒ `String` #each_line(separator = $/, chomp: false) ⇒ `Object`

#empty? ⇒ `Boolean`

#encode(encoding, options) ⇒ `String` #encode(dst_encoding, src_encoding, options) ⇒ `String` #encode(**options) ⇒ `String`

#encode!(encoding, options) ⇒ `String` #encode!(dst_encoding, src_encoding, options) ⇒ `String`

#encoding ⇒ `Encoding`

#end_with?([suffixes]) ⇒ `Boolean`

#eql?(object) ⇒ `Boolean`

#force_encoding(encoding) ⇒ `String`

#freeze ⇒ `Object`

#getbyte(index) ⇒ `0 .. 255`

#grapheme_clusters ⇒ `Array`

#gsub(pattern, replacement) ⇒ `String` #gsub(pattern, hash) ⇒ `String` #gsub(pattern) {|match| ... } ⇒ `String` #gsub(pattern) ⇒ `Object`

#gsub!(pattern, replacement) ⇒ `String`^? #gsub!(pattern, hash) ⇒ `String`^? #gsub!(pattern) {|match| ... } ⇒ `String`^? #gsub!(pattern) ⇒ `Object`

#hash ⇒ `Integer`

#hex ⇒ `Integer`

#include?(other_str) ⇒ `Boolean`

#index(substring, offset = 0) ⇒ `Integer`^? #index(regexp, offset = 0) ⇒ `Integer`^?

#replace(other_str) ⇒ `String`

#insert(index, other_string) ⇒ `self`

#inspect ⇒ `String`

#intern ⇒ `Object` #to_sym ⇒ `Object`

#length ⇒ `Integer`

#lines(separator = $/, chomp: false) ⇒ `Array`

#ljust(integer, padstr = ' ') ⇒ `String`

#lstrip ⇒ `String`

#lstrip! ⇒ `self`^?

#match(pattern, offset = 0) ⇒ `MatchData`^? #match(pattern, offset = 0) {|matchdata| ... } ⇒ `Object`

#match?(pattern, offset = 0) ⇒ `Boolean`

#succ ⇒ `String`

#succ! ⇒ `self`

#oct ⇒ `Integer`

#ord ⇒ `Integer`