PHP allows you to declare the types of values that functions should return, ensuring clarity and type safety within your codebase. Return type declarations were introduced in PHP 7.0 and support specifying scalar types (like int, float, string, bool) as well as array and object, among others. Here’s how you can use return type declarations effectively in PHP:

Basic Return Type Declarations

Scalar Types

Scalar types include int, float, string, and bool. You specify the return type by appending a colon (:) followed by the type after the closing parenthesis of the parameter list.

Example:

php
<?php
        function addNumbers(int $a, int $b): int {
            return $a + $b;
        }
        
        $result = addNumbers(5, 3); // $result will be of type int
        echo $result; // Outputs: 8
        ?>
        

void Type

The void type indicates that the function does not return any value. Prior to PHP 7.1, void was only allowed as a return type for functions.

Example:

php
<?php
        function logMessage(string $message): void {
            // Log the message somewhere
            echo "Logged: $message";
        }
        
        logMessage("Error occurred."); // Outputs: Logged: Error occurred.
        ?>
        

Nullable Return Types

Return types can be nullable by appending a question mark (?) before the type declaration. This means the function can return either the specified type or null.

Example:

php
<?php
        function findUserById(int $userId): ?string {
            if ($userId === 1) {
                return "John Doe";
            } else {
                return null;
            }
        }
        
        $user = findUserById(1);
        echo "User: $user"; // Outputs: User: John Doe
        ?>
        

array and object Return Types

You can specify that a function returns an array or an object by using these type declarations.

Example with array:

php
<?php
        function getNumbers(): array {
            return [1, 2, 3, 4, 5];
        }
        
        $numbers = getNumbers();
        print_r($numbers); // Outputs: Array ( [0] => 1, [1] => 2, [2] => 3, [3] => 4, [4] => 5 )
        ?>
        

Example with object:

php
<?php
        class User {
            public $name;
            public $age;
        
            public function __construct(string $name, int $age) {
                $this->name = $name;
                $this->age = $age;
            }
        }
        
        function createUser(): object {
            return new User("John Doe", 30);
        }
        
        $user = createUser();
        echo "User: {$user->name}, Age: {$user->age}"; // Outputs: User: John Doe, Age: 30
        ?>
        

Summary:

Return type declarations in PHP help enforce stricter type checking and provide clearer documentation of expected function behaviors. They improve code readability and maintainability by explicitly defining what type of data a function will return. Use them effectively to ensure your PHP codebase remains robust and easy to understand.