字符串截取指定下标的内容

 　　　　　　　　<?php
                                                            mb_internal_encoding("utf-8");
                                                            $pp = "";
                                                            foreach ($doc as $key => $value) {

                                                                if (mb_strpos($value, $_GET["q"])) {
　　　　　　　　　　　　　　　　　　　　　　　　//关键代码
                                                                    $pp = $key . ":" . $search->highlight(mb_substr($value, mb_strpos($value, $_GET["q"]), 100)) . '...';
                                                                    echo $pp;
                                                                    break;
                                                                }
                                                            }
                                                           
                                                            ?>