多个PHP中文字符串截取函数

<?php
functionsysSubStr($string,$length,$append=false)
{
   if(strlen($string)<=$length)
   {
       return$string;
   }
   else
   {
       $i=0;
       while($i<$length)
       {
           $stringTMP=substr($string,$i,1);
           if(ord($stringTMP)>=224)
           {
               $stringTMP=substr($string,$i,3);
               $i=$i+3;
           }
           elseif(ord($stringTMP)>=192)
           {
               $stringTMP=substr($string,$i,2);
               $i=$i+2;
           }
           else
           {
               $i=$i+1;
           }
           $stringLast[]=$stringTMP;
       }
       $stringLast=implode("",$stringLast);
       if($append)
       {
           $stringLast.="...";
       }
       return$stringLast;
   }
}

$string="简明现代魔法——专注于互联网主流的各种技术";
$length="27";
$append=true;
echosysSubStr($string,$length,$append);
//输出
//简明现代魔法——专...
?>