How to Specify Return Value Types for Functions in PHP? Improve Code Readability and Maintainability

M66 2025-07-12

How to Specify Function Return Value Types in PHP

In PHP, the return value type of a function can be specified using type hinting. This not only enhances code readability but also improves maintainability and testability. Type hinting ensures that the function returns data in the expected type, preventing potential type errors.

Using Type Hinting to Specify Return Value Types

After the function declaration in PHP, you can specify the return type using a colon (:). Here's a simple example:

function get_name(): string {
    return 'Alice';
}

In this example, the get_name() function is declared to return a string.

Supported Return Types

PHP supports the following built-in types for function return values:

array: Arrays
callable: Callable types
bool: Boolean values
float: Floating-point values (can also use double)
int: Integers
string: Strings
void: No return value

Additionally, you can use custom classes and interfaces as return types.

Using Custom Classes as Return Value Types

In PHP, you can specify custom classes as return types. Here’s a simple example:

class Person {
    // ...
}

function create_person(): Person {
    // ...
}

In the above example, the create_person() function is declared to return a Person object.

Practical Example: Using Type Hinting to Calculate the Sum of Two Numbers

The following example demonstrates a function that uses type hinting to calculate the sum of two integers:

function calculate_sum(int $x, int $y): int {
    return $x + $y;
}

You can use the function like this:

$result = calculate_sum(5, 10); // Result: 15

Things to Keep in Mind

Type hinting is optional. If no type is specified, the function's return type defaults to mixed.
Type hinting is supported in PHP 7.0 and higher.
If the function's return value does not match the declared type, PHP will throw a TypeError.

By properly using type hinting, PHP developers can better control function return values and enhance code safety and maintainability.

array