HTML 简易计算器代码示例 - 使用表单实现计算功能

<h1>简易计算器</h1>

<form>
	<label>第一个数:</label>
	<input type='number' name='num1' required>
	<br><br>
	<label>第二个数:</label>
	<input type='number' name='num2' required>
	<br><br>
	<label>选择运算符:</label>
	<select name='operator'>
		<option value='+'>加</option>
		<option value='-'>减</option>
		<option value='*'>乘</option>
		<option value='/'>除</option>
	</select>
	<br><br>
	<input type='submit' value='计算'>
</form>

<?php 
	if(isset($_GET['num1']) && isset($_GET['num2']) && isset($_GET['operator']))
	{
		$num1 = $_GET['num1'];
		$num2 = $_GET['num2'];
		$operator = $_GET['operator'];

		if($operator == '+')
		{
			$result = $num1 + $num2;
		}
		elseif($operator == '-')
		{
			$result = $num1 - $num2;
		}
		elseif($operator == '*')
		{
			$result = $num1 * $num2;
		}
		elseif($operator == '/')
		{
			$result = $num1 / $num2;
		}

		echo '<p>计算结果: $result</p>';
	}
?>