适应中文的substr函数_PHP

SUBSTR

function SubstrGB($in,$num){

        $pos=0;

        $out="";

        while($c=substr($in,$pos,1)){

            if($c=="\n") break;

            if(ord($c)>128){

                $out.=$c;

                $pos++;

                $c=substr($in,$pos,1);

                $out.=$c;

            }

            else{

                $out.=$c;

            }

            $pos++;

            if($pos>=$num) break;

        }

        return $out;