中英文字符串翻转函数

<?php 
//页面编码设为utf8 
header('Content-type: text/html; charset=utf-8'); 
$luokuan = "ABCDEFG-测试的啊-!!!一二三四五。。"; 
$n = mb_strlen("$luokuan","UTF-8"); 
//echo $n; 
$newluokuan = ""; 
for ($i=$n;$i>=0;$i--) 
{ $newluokuan.= mb_substr($luokuan,$i,1,'UTF-8'); 
} 
echo $newluokuan; 
?>