用php做个简单的计算

内容摘要
这篇文章主要为大家详细介绍了用php做个简单的计算，具有一定的参考价值，可以用来参考一下。
文章正文

这篇文章主要为大家详细介绍了用php做个简单的计算，具有一定的参考价值，可以用来参考一下。

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<code><!DOCTYPE html>
<html>
    <head>
        <title>PHP实现计算器</title>
    </head>
 
    <body>
        <?php
            $mess = "";
            if(isset($_POST["sub"])){
                if($_POST["num1"] == ""){
                    $mess .= "第一个数不能为空!<br>";
                }
                else{
                    if(!is_numeric($_POST["num1"])){
                        $mess .="第一个数必须是数字!<br>";
                    }
                }
 
                if($_POST["num2"]==""){
                    $mess .="第二个数不能为空!<br>";
                }
                else{
                    if(!is_numeric($_POST["num2"])){
                        $mess .="第二个数必须是数字!<br>";
                    }
                    else{
                        if($_POST["opt"]=="/"&&$_POST["num2"]==0){
                            $mess .="除数不能为0";
                        }
                    }
                }
            }
        ?>
<table border="1" align="center" width="400">
    <form action="" method="post">
        <caption><h1>计算器</h1></caption>
        <tr>
            <td>
                <input type="text" size="4" name="num1" value="<?php echo $_POST["num1"]?>" />
            </td>
 
            <td>
                <select name="opt">
                    <option value="+" <?php echo $_POST["opt"]=="+" ? "selected" : "" ?>>+</option>
                    <option value="-" <?php echo $_POST["opt"]=="-" ? "selected" : "" ?>>-</option>
                    <option value="x" <?php echo $_POST["opt"]=="x" ? "selected" : "" ?>>x</option>
                    <option value="/" <?php echo $_POST["opt"]=="/" ? "selected" : "" ?>>/</option>
                    <option value="%" <?php echo $_POST["opt"]=="%" ? "selected" : "" ?>>%</option>
                </select>
            </td>
 
            <td>
                <input type="text" size="4" name="num2" value="<?php echo $_POST["num2"]?>" />
            </td>
 
            <td>
                <input type="submit" name="sub" value="计算" />
            </td>
        </tr>
    </form>
    <?php
        if(isset($_POST["sub"])){
            echo '<tr><td colspan="4">';
            if(!$mess){
                $sum=0;
                switch($_POST["opt"]){
                    case "+":
                        $sum = $_POST["num1"] + $_POST["num2"];
                        break;
                    case "-":
                        $sum = $_POST["num1"] - $_POST["num2"];
                        break;
                    case "x":
                        $sum = $_POST["num1"] * $_POST["num2"];
                        break;
                    case "/":
                        $sum = $_POST["num1"] / $_POST["num2"];
                        break;
                    case "%":
                        $sum = $_POST["num1"] % $_POST["num2"];
                        break;
                }
 
                echo "结果:{$_POST['num1']} {$_POST['opt']} {$_POST['num2']} = {$sum}";
            }
            else{
                echo $mess;
            }
            echo '</td></tr>';
        }
    ?>
</table>
    </body>
</html></code>

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