How to determine the type of PHP function parameters

The function parameter type can be determined in the PHP language through the following methods: is_ function: Use the is_ function to check the variable type, such as is_int() and is_array(). Type hint: Specify the expected type in the function parameter, using the : syntax, such as function calculate_total(array $products).

How to determine the type of PHP function parameters

PHP is a weakly typed language, which means it checks at runtime Variable type. However, in some cases it can be useful to know the types of function parameters.

Using the is_ function

To determine the type of a variable, you can use the built-in is_ function. For example:

if (is_int($param)) {
    // 参数是整数
} elseif (is_string($param)) {
    // 参数是字符串
} elseif (is_array($param)) {
    // 参数是数组
}

This is a practical case using the is_ function:

function calculate_total($products) {
    $total = 0;

    if (!is_array($products)) {
        throw new InvalidArgumentException("Product list must be an array");
    }

    foreach ($products as $product) {
        if (!is_array($product) || !array_key_exists('price', $product)) {
            throw new InvalidArgumentException("Invalid product format");
        }

        $total += $product['price'];
    }

    return $total;
}

// 使用函数
$products = [
    ['price' => 10],
    ['price' => 15]
];
$total = calculate_total($products);
echo "Total: $total";

Using type hints

Introduced by PHP 7 Type hinting feature allows you to specify the expected type in function parameters. For example:

function calculate_total(array $products) {
    // 参数被提示为数组
}

A practical example of using type hints:

function calculate_total(array $products): float {
    // 参数被提示为数组并且返回值被提示为浮点数

    $total = 0;
    foreach ($products as $product) {
        $total += $product['price'];
    }

    return $total;
}

// 使用函数
$products = [
    ['price' => 10],
    ['price' => 15]
];
$total = calculate_total($products);
echo "Total: $total";

By using is_ functions or type hints, you can determine the type of PHP function parameters and write more Robust, more reliable code.

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