php 简易计算器

<?php
    $num1 = $_GET['num1'];
    $num2 = $_GET['num2'];
    $opt = $_GET['opt'];
    $result = 0;
    if(!is_numeric($num1)){
        $result = '请输入数字1';
    }else if(!is_numeric($num2)){
        $result = '请输入数字2';
    }else{
        switch($opt){
            case '+':
                $result = $num1 + $num2;
                break;
            case '-':
                $result = $num1 - $num2;
                break;
            case '*':
                $result = $num1 * $num2;
                break;
            case '/':
                if($num2 == '0'){
                    $result = '除数不能为0 ！';
                }else
                {
                    $result = $num1 / $num2;
                }
                break;
            case '%':
                if($num2 == '0'){
                    $result = '除数不能为0 ！';
                }else
                {
                    $result = $num1 % $num2;
                }
                break;
            default:
                $result = '无效运算！';
        };
    }
?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <form action="" method="get" style="width:20em;display:grid;grid-template-columns:30% 70%;gap:1em;">
        <label>数字1：</label><input type="number" name="num1" value="<?= isset($_GET['num1'])?$num1 :'' ?>">
        <label>运算符:</label>
        <select name="opt" id="">
            <option value="+" <?= ($opt == '+') ? 'selected':'' ?> >+</option>
            <option value="-" <?= ($opt == '-') ? 'selected':'' ?> >-</option>
            <option value="*" <?= ($opt == '*') ? 'selected':'' ?> >*</option>
            <option value="/" <?= ($opt == '/') ? 'selected':'' ?> >/</option>
            <option value="%" <?= ($opt == '%') ? 'selected':'' ?> >%</option>
        </select>
        <label>数字2：</label><input type="number" name="num2" value="<?= isset($_GET['num2']) ?$num2 : '' ?>">
        <label>结 果：</label><input type="text" value = "<?= $result ?>">
        <label></label><input type="submit" value="提交">
    </form>
</body>
</html>
运行结果：
zy1
zy2
php 简易计算器

php 简易计算器

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