How to check the type of function return value in PHP?

PHP provides three methods to check the function return value type: 1. Use the gettype() function; 2. Use the is_*() function; 3. Use the instanceof operator. These methods ensure code robustness and avoid unexpected errors.

#How to check the type of function return value in PHP?

PHP provides several methods to check the type of function return value. The most commonly used methods are listed below:

1. Use the gettype() function

gettype() function Returns a string representing the variable's type. For example:

<?php
function myFunction() {
    return "Hello World";
}

$result = myFunction();

echo gettype($result); // 输出：string
?>

2. Use the is_*() function

PHP provides a series of is_*() Function to check if a variable is of a specific type. For example:

<?php
function myFunction() {
    return "Hello World";
}

$result = myFunction();

if (is_string($result)) {
    echo "结果是字符串";
}
?>

3. Use the instanceof operator

instanceof operator to check whether an object belongs to a specific class . For example:

<?php
class MyClass {
    public function myMethod() {
        return "Hello World";
    }
}

function myFunction() {
    return new MyClass();
}

$result = myFunction();

if ($result instanceof MyClass) {
    echo "结果是一个 MyClass 对象";
}
?>

Practical case

Suppose you have a function get_user_data(), which returns an array of user data. You can use the is_array() function to check whether the return value is an array:

<?php
function get_user_data($user_id) {
    // 从数据库获取用户数据
    $user_data = [
        'id' => 1,
        'name' => 'John Doe',
    ];

    return $user_data;
}

$user_id = 1;
$result = get_user_data($user_id);

if (is_array($result)) {
    // 执行一些操作，因为 $result 是一个数组
} else {
    // 执行一些其他操作
}
?>

By checking the type of a function return value, you can write more robust code and avoid unexpected errors.

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