字符串转数组/得到字符串长度

//字符串长度function strlen_2($str){    for($len =0;;$len++) if(!isset($str[$len])) break;    return $len;}dump(strlen_2('1203gh4'));//字符串转数组function str_split_2($str){    $arr = array();    for($len = 0;;$len++) {        if(!isset($str[$len])) break;        $arr[] = $str[$len];    };    return $arr;}dump(str_split_2('12s0d45'));