//$str 待截取的字符串//$len 截取的字符个数//$chars 已经截取的字符数//$res   保存的字符串//$chars 保存已经截取的字符串个数//$offset 截取的偏移量//$length 字符串的字节数//若$len>$str的字符个数，造成无谓的while循环，($offset<$length限定) function pub_rep($str,$len){     $res="";     $info="";     $offset=0;     $chars=0;     $length=strlen($str);     while($chars<$len && $offset<$length){         $hign=decbin(ord(substr($str,$offset,1)));         if(strlen($hign)<8){             $count=1;         }elseif(substr($hign,0,3)=="110"){             $count=2;         }elseif(substr($hign,0,4)=="1110"){             $count=3;         }elseif(substr($hign,0,5)=="11110"){             $count=4;         }elseif(substr($hign,0,6)=="111110"){             $count=5;         }elseif(substr($hign,0,7)=="1111110"){             $count=6;         }         $res.=substr($str,$offset,$count);         $offset+=$count;         $chars+=1;     }     $rep="...";     $res.=$rep;     return $res; }