PHP -- four arithmetic operation

PHP 生成 简单四则运算。

Thanks for Open Source.

本代码基于 jiaych php四则运算计算函数实现。

 <?php
     /*基于jiaych php四则运算计算函数
     http://download.csdn.net/user/jiaych 实现

     */
     class randmath
     {
           //$num 数字个数，$nsize 数字位数
           public function creatmath($num, $nsize)
           {
                 $str_num = rand(0, pow(10,$nsize));
                 for ($i = 1; $i < $num; $i++) {
                 $str_t=rand(0, pow(10,$nsize)); 

                      $str_num = $this->rand_num($str_num, rand(0, pow(10,$nsize)));

                 }
                 return $str_num;
           }
           //生成四则运算符号
          function rand_num($str1, $str2)
           {
                $s_num = rand(1, 4);
                 $str="";
                 switch ($s_num) {
                       case 1: //+
                             $str= $str1 . "+" . $str2;
                             break;
                       case 2: //-
                             $str= $str1 . "-" . $str2;
                             break;
                       case 3: //*
                             $str= $str1 . "*" . $str2;
                             break;
                       case 4: // /
                             $str= $str1 . "/" . $str2;
                             break;
                             /* case 5: //（）
                             echo "</br>" . $s_num;
                             return $str1."+".$str2;
                             break; */
                 }
                 return $str;
           }
     }
     class math_rpn {

     function exp2rpn($expression){

         $_stack  = array('#');
         $_rpnexp = array();
         $_operator = array('(', '+', '-', '*', '/', ')');
         $_priority = array('#' => 0, '(' => 10, '+' => 20, '-' => 20, '*' => 30, '/' => 30);
         $data='';
         $len = strlen($expression);

         for($i = 0; $i < $len; $i++) {
             $char = substr($expression, $i, 1);

             if ($char == '(') {
                 $_stack[] = $char;
                 continue;
             } else if ( ! in_array($char, $_operator)) {
                 $data.=$char;
                 if($i+1<$len)
                 {
                     $next = substr($expression, $i+1, 1);
                     if(in_array($next, $_operator)||is_null($next))
                     {
                         $_rpnexp[] = $data;
                         $data=null;
                     }
                 }
                 else
                 {
                     $_rpnexp[] = $data;
                     $data=null;
                 }
                 continue;
             } else if ($char == ')') {
                 for($j = count($_stack); $j >= 0; $j--) {
                     $tmp = array_pop($_stack);
                     if ($tmp == "(") {
                         break;
                     } else {
                         $_rpnexp[] = $tmp;
                     }
                 }
                 continue;
             } else if ($_priority[$char] <= $_priority[end($_stack)]) {
                 $_rpnexp[] = array_pop($_stack);
                 $_stack[]  = $char;
                 continue;
             } else {
                 $_stack[] = $char;
                 continue;
             }
         }

         for($i = count($_stack); $i >= 0; $i--) {
             if (end($_stack) == '#') break;
             $_rpnexp[] = array_pop($_stack);
         }
         $mystack=array();
         foreach($_rpnexp as $ret)
         {
             if($ret=="+")
             {
                 $tmp_a=array_pop($mystack);
                 $tmp_b=array_pop($mystack);
                 $mystack[]=$tmp_a+$tmp_b;
             }
             else if($ret=="-")
             {
                 $tmp_a=array_pop($mystack);
                 $tmp_b=array_pop($mystack);
                 $mystack[]=$tmp_b-$tmp_a;
             }
             else if($ret=="*")
             {
                 $tmp_a=array_pop($mystack);
                 $tmp_b=array_pop($mystack);
                 $mystack[]=$tmp_b*$tmp_a;
             }
             else if($ret=="/")
             {
                 $tmp_a=array_pop($mystack);
                 $tmp_b=array_pop($mystack);
                 $mystack[]=$tmp_b/$tmp_a;
             }
             else
             {
                 $mystack[]=$ret;
             }
         }
         return $mystack[0];
     }
 }//测试实例
 /*$expression = "(10.1+3)*(15)-1.4+5";
 echo $expression."=";
 $mathrpn = new math_rpn();
 echo $mathrpn->exp2rpn($expression)."</br>";
 */
   //  $rand_math = new randmath();
   //  echo $rand_math->creatmath(4, 2);
 ?>

randmath.php

  <?php
     header("Content-type: text/html; charset=utf-8");
     include("randmath.php");

     $mathrpn = new math_rpn();
     $rand_math  = new randmath();//生成随机式子

     $i=10;
     while($i>0)
     {
         $rand_formula = $rand_math->creatmath(4, 1);//生成随机式子方法（$num 数字个数，$nsize 数字位数）
         $math_result=$mathrpn->exp2rpn($rand_formula);
         if(is_int($math_result)&$math_result>0)
         {
             $i--;
             echo $rand_formula . "=" . $math_result."</br>";
         }
     }
 ?> 

ShowRPN.php

这样就能生成简单四则运算了。