本函数可能理论上说有些不地道，把utf-8的中文字符和char一视同仁，都按长度为1计算

 

function string_substring($string,$start,$length) {     $countstart=0;     $countlength=0;     $printstring="";     for($i=0;$i
     
      128)             {                 $i+=3;             }             else            {                 $i++;             }         }         while($countlength<$length)         {             $countlength++;             if(ord(substr($string,$i,1))>128)             {                 $printstring.=substr($string,$i,3);                 $i+=3;             }             else            {                 $printstring.=substr($string,$i,1);                 $i++;             }         }     }     return $printstring; }
     

 

示例：

echo string_substring(">>我是A一个兵",1,4);

显示：

>我是A