Method: IO#ungetbyte

Defined in:

io.c

#ungetbyte(string) ⇒ nil #ungetbyte(integer) ⇒ nil

Pushes back bytes (passed as a parameter) onto ios, such that a subsequent buffered read will return it. Only one byte may be pushed back before a subsequent read operation (that is, you will be able to read only the last of several bytes that have been pushed back). Has no effect with unbuffered reads (such as IO#sysread).

f = File.new("testfile")   #=> #<File:testfile>
b = f.getbyte              #=> 0x38
f.ungetbyte(b)             #=> nil
f.getbyte                  #=> 0x38

Overloads:

• #ungetbyte(string) ⇒ nil

  Returns:

  • (nil)
• #ungetbyte(integer) ⇒ nil

  Returns:

  • (nil)

# File 'io.c', line 3910

VALUE
rb_io_ungetbyte(VALUE io, VALUE b)
{
    rb_io_t *fptr;

    GetOpenFile(io, fptr);
    rb_io_check_byte_readable(fptr);
    if (NIL_P(b)) return Qnil;
    if (FIXNUM_P(b)) {
  char cc = FIX2INT(b);
  b = rb_str_new(&cc, 1);
    }
    else {
  SafeStringValue(b);
    }
    io_ungetbyte(b, fptr);
    return Qnil;
}