<?php  /**  * title: 判斷表達式中括號是否匹配  * Description: () 匹配 )(不匹配 利用壓棧和出棧  * @author Mr Lv    */   function isValid($expstr) {   $temp = array();   for ($i=0; $i<strlen($expstr); $i++) {     $ch = $expstr[$i];     switch($ch) {       case '(':         array_push($temp, '(');         break;       case ')':         if (empty($temp) || array_pop($temp) != '(') {           return "缺少左括號（";         }     }   }   return empty($temp) == true ? "表達式匹配" : "缺少右括號）"; } $expstrA = "(1+3(6*4)-(2+3))()("; $expstrB = "(1+3(6*4)-(2+3))()"; $expstrC = "(1+3(6*4)-(2+3)))"; echo isValid($expstrA); echo "<br>"; echo isValid($expstrB); echo "<br>"; echo isValid($expstrC); ?> 

缺少右括號） 表達式匹配 缺少左括號（