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);
?>

 <?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>";
        }          
    }
?> 

这样就能生成简单四则运算了。