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'));