Question

我是php的初学者。我试图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;

它打印的值如下

10+5
10-5

如何编辑我的代码才能进行此算术运算？

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。

这很多，很多更安全：

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");
    }
}

现在你可以致电：

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

Answer 2

这对你有用！

您可以使用此功能：

function calculate_string( $mathString )    {
    $mathString = trim($mathString);     // trim white spaces
    $mathString = preg_replace ('[^0-9\+-\*\/\(\) ]', '', $mathString);    // remove any non-numbers chars; exception for math operators

    $compute = create_function("", "return (" . $mathString . ");" );
    return 0 + $compute();
}

//As an example
echo calculate_string("10+5");

输出：

所以在你的情况下你可以这样做：

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

$num1 = 10;
$num2 = 5;

echo calculate_string($num1 . $operators[array_rand($operators)] . $num2);

变量之间的算术运算

2 个答案: