php 万能截取字符串

PHP截取字符串

function OmiStr($str,$num = 25) {
    $str = rawurldecode($str);
    preg_match_all("/(?:%u.{4})|&#x.{4};|&#\d+;|.+/U",$str,$r);
    $ar = $r[0];
    //print_r($ar);
    foreach($ar as $k=>$v){
        if(substr($v,0,2) == "%u")
            $ar[$k] = iconv("UCS-2",mb_internal_encoding(),pack("H4",substr($v,-4)));
        elseif(substr($v,0,3) == "&#x")
            $ar[$k] = iconv("UCS-2",mb_internal_encoding(),pack("H4",substr($v,3,-1)));
        elseif(substr($v,0,2) == "&#") {
            $ar[$k] = iconv("UCS-2",mb_internal_encoding(),pack("n",substr($v,2,-1)));
        }
    }
    $Com_Str = join("",$ar);
    $Ser_Str = mb_substr($Com_Str,0,$num,mb_internal_encoding());
       if($Com_Str == $Ser_Str){
        return $Ser_Str;
    }
    else{
        return $Ser_Str."...";
    }

}