php 完成简易计算器程序

在 PHP 中完成一个简单的计算器程序，可以使用基本的流程控制结构如条件语句（if-else）和循环来实现加、减、乘、除的功能。下面是一个基础示例：

<?php
class Calculator {
    public function add($num1, $num2) {
        return $num1 + $num2;
    }

    public function subtract($num1, $num2) {
        return $num1 - $num2;
    }

    public function multiply($num1, $num2) {
        return $num1 * $num2;
    }

    public function divide($num1, $num2) {
        // 需要检查除数是否为0，防止错误
        if ($num2 != 0) {
            return $num1 / $num2;
        } else {
            return "Error: Division by zero is not allowed.";
        }
    }
}

// 创建计算器实例
$calculator = new Calculator();

// 用户输入操作和数字
echo "Enter operation (+, -, *, /): ";
$operation = trim(fgets(STDIN));

echo "Enter first number: ";
$num1 = (float) fgets(STDIN);

echo "Enter second number: ";
$num2 = (float) fgets(STDIN);

// 根据用户输入执行相应的计算
switch ($operation) {
    case '+':
        echo "Result: " . $calculator->add($num1, $num2) . "\n";
        break;
    case '-':
        echo "Result: " . $calculator->subtract($num1, $num2) . "\n";
        break;
    case '*':
        echo "Result: " . $calculator->multiply($num1, $num2) . "\n";
        break;
    case '/':
        echo $calculator->divide($num1, $num2);
        break;
    default:
        echo "Invalid operation. Please use one of the following: +, -, *, /\n";
}
?>