How to check PHP function parameter types?

Methods for checking function parameter types in PHP: use typehints to specify parameter and return value types, and throw a TypeError exception; use getType() to get the actual type of the variable, which is used for conditional statements; use assert() to check the condition, when it is false Throws AssertionError exception and error message.

How to check PHP function parameter types

Preface

In modern development , type checking is becoming more and more important, it can improve the maintainability and reliability of the code. The PHP language provides several methods to check function parameter types.

Method 1: Use typehints

Typehints are a syntactic sugar introduced in PHP 7 that allows you to specify the expected types of parameters in a function declaration.

function add(int $a, int $b): int {
    return $a + $b;
}

int typehint specifies that the parameters and return value are both integer types. If the argument passed is not an integer, PHP will throw a TypeError exception.

Method 2: Use getType()

getType() function to get the actual type of the variable.

function isString(mixed $value): bool {
    return gettype($value) === 'string';
}

mixed typehint The specified parameter can be of any type. gettype() The function returns the actual type of the variable for use in conditional statements.

Method 3: Use assert()

assert() The function can check conditions at runtime. If the condition is false, it will throw an AssertionError exception.

function validateEmail(string $email): void {
    assert(filter_var($email, FILTER_VALIDATE_EMAIL), 'Invalid email address');
}

assert() The function accepts two parameters: condition and error message. If the condition is false, it will throw an AssertionError exception and display an error message.

Practical case

Suppose we have a function that processes user input. We can use typehints and assert() to check if the input is valid:

function processInput(array $data): void {
    assert(array_key_exists('name', $data), 'Missing "name" field');
    assert(array_key_exists('email', $data), 'Missing "email" field');
    assert(filter_var($data['email'], FILTER_VALIDATE_EMAIL), 'Invalid email address');

    // 处理经过验证的输入...
}

In this example, we ensure that the $data array contains name and email fields, and the email address is valid. If these conditions are not met, an AssertionError exception is raised and an appropriate error message is displayed.

The above is the detailed content of How to check PHP function parameter types?. For more information, please follow other related articles on the PHP Chinese website!