php - 变量之间的算术运算

Question

我是 php 的初学者。我正在尝试在两个变量之间应用一些随机算术运算

$operators = array(
    "+",
    "-",
    "*",
    "/"
    );

$num1 = 10;
$num2 = 5;

$result = $num1 . $operators[array_rand($operators)] . $num2;

echo $result;

它打印出这样的值

10+5
10-5

如何编辑我的代码以执行此算术运算？

Answer 1

虽然您可以使用 eval() 来执行此操作，但它依赖于安全的变量。

这要安全得多，多:

function compute($num1, $operator, $num2) {
    switch($operator) {
        case "+": return $num1 + $num2;
        case "-": return $num1 - $num2;
        case "*": return $num1 * $num2;
        case "/": return $num1 / $num2;

        // you can define more operators here, and they don't
        // have to keep to PHP syntax. For instance:
        case "^": return pow($num1, $num2);

        // and handle errors:
        default: throw new UnexpectedValueException("Invalid operator");
    }
}

现在你可以调用:

echo compute($num1, $operators[array_rand($operators)], $num2);