用PHP实现的四则运算表达式计算

题目要求：有一个四则运算的字符串表达式，编写一个函数，计算四则运算的结果

PHP实现：

 1 <?php

 2

 3 /**

 4  * 计算四则运算表达式

 5  */

 6

 7 error_reporting(E_ALL);

 8

 9 $exp = '(1+2*(3+5)/4)*(3+(5-4)*2)';

10 $arr_exp = array();

11

12 for($i=0;$i<strlen($exp);$i++){

13     $arr_exp[] = $exp[$i];

14 }

15 $result = calcexp( array_reverse($arr_exp) );

16 echo $exp . '=' . $result;

17

18 function calcexp( $exp ){

19     $arr_n = array();

20     $arr_op = array();

21    

22     while( ($s = array_pop( $exp )) != '' ){

23         if( $s == '(' ){

24             $temp = array(); $quote = 1; $endquote = 0;

25             while( ($t = array_pop($exp)) != '' ){

26                 if( $t == '(' ){

27                     $quote++;

28                 }

29                 if( $t == ')' ){

30                     $endquote++;

31                     if( $quote == $endquote ){

32                         break;

33                     }

34                 }

35                 array_push($temp, $t);

36             }

37             $temp = array_reverse($temp);

38             array_push($arr_n, calcexp($temp) );

39         }else if( $s == '*' || $s == '/' ){

40             $n2 = array_pop($exp);

41             if( $n2 == '(' ){

42                 $temp = array(); $quote = 1; $endquote = 0;

43                 while( ($t = array_pop($exp)) != '' ){

44                     if( $t == '(' ){

45                         $quote++;

46                 &nb