method

shift

Ruby latest stable (v1_8_6_287) - 0 notes - Class: Array

shift() public

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

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

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/*
 *  call-seq:
 *     array.shift   ->   obj or nil
 *  
 *  Returns the first element of <i>self</i> and removes it (shifting all
 *  other elements down by one). Returns <code>nil</code> if the array
 *  is empty.
 *     
 *     args = [ "-m", "-q", "filename" ]
 *     args.shift   #=> "-m"
 *     args         #=> ["-q", "filename"]
 */

VALUE
rb_ary_shift(ary)
    VALUE ary;
{
    VALUE top;

    rb_ary_modify_check(ary);
    if (RARRAY(ary)->len == 0) return Qnil;
    top = RARRAY(ary)->ptr[0];
    if (RARRAY_LEN(ary) < ARY_DEFAULT_SIZE && !FL_TEST(ary, ELTS_SHARED)) {
        MEMMOVE(RARRAY_PTR(ary), RARRAY_PTR(ary)+1, VALUE, RARRAY_LEN(ary)-1);
    }
    else {
        if (!FL_TEST(ary, ELTS_SHARED)) {
            RARRAY(ary)->ptr[0] = Qnil;
        }
        ary_make_shared(ary);
        RARRAY(ary)->ptr++;            /* shift ptr */
    }
    RARRAY(ary)->len--;

    return top;
}

shift

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