<?php

        function subString($string,$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 = "输不起de青春 —— phper";

        $length = "26";

        $append = true;

        echo subString($string,$length,$append);

?>