index

/*
 *  call-seq:
 *     array.index(obj)           ->  int or nil
 *     array.index {|item| block} ->  int or nil
 *  
 *  Returns the index of the first object in <i>self</i> such that is
 *  <code>==</code> to <i>obj</i>. If a block is given instead of an
 *  argument, returns first object for which <em>block</em> is true.
 *  Returns <code>nil</code> if no match is found.
 *     
 *     a = [ "a", "b", "c" ]
 *     a.index("b")        #=> 1
 *     a.index("z")        #=> nil
 *     a.index{|x|x=="b"}  #=> 1
 *
 *  This is an alias of <code>#find_index</code>.
 */

static VALUE
rb_ary_index(argc, argv, ary)
    int argc;
    VALUE *argv;
    VALUE ary;
{
    VALUE val;
    long i;

    if (argc  == 0) {
        RETURN_ENUMERATOR(ary, 0, 0);
        for (i=0; i<RARRAY(ary)->len; i++) {
            if (RTEST(rb_yield(RARRAY(ary)->ptr[i]))) {
                return LONG2NUM(i);
            }
        }
        return Qnil;
    }
    rb_scan_args(argc, argv, "01", &val);
    for (i=0; i<RARRAY(ary)->len; i++) {
        if (rb_equal(RARRAY(ary)->ptr[i], val))
            return LONG2NUM(i);
    }
    return Qnil;
}