Method: Array#shift

Defined in:
array.c

#shift ⇒ Object? #shift(n) ⇒ Array

Removes the first element of self and returns it (shifting all other elements down by one). Returns nil if the array is empty.

If a number n is given, returns an array of the first n elements (or less) just like array.slice!(0, n) does. With ary containing only the remainder elements, not including what was shifted to new_ary. See also Array#unshift for the opposite effect.

args = [ "-m", "-q", "filename" ]
args.shift     #=> "-m"
args           #=> ["-q", "filename"]

args = [ "-m", "-q", "filename" ]
args.shift(2)  #=> ["-m", "-q"]
args           #=> ["filename"]

Overloads:



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# File 'array.c', line 1054

static VALUE
rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE result;
    long n;

    if (argc == 0) {
	return rb_ary_shift(ary);
    }

    rb_ary_modify_check(ary);
    result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
    n = RARRAY_LEN(result);
    if (ARY_SHARED_P(ary)) {
	if (ARY_SHARED_OCCUPIED(ARY_SHARED(ary))) {
	    ary_mem_clear(ary, 0, n);
	}
        ARY_INCREASE_PTR(ary, n);
    }
    else {
	RARRAY_PTR_USE(ary, ptr, {
	    MEMMOVE(ptr, ptr + n, VALUE, RARRAY_LEN(ary)-n);
	}); /* WB: no new reference */
    }
    ARY_INCREASE_LEN(ary, -n);

    return result;
}