Return Type Declarations

Part of the Fundamentals section of Coddy's PHP journey — lesson 66 of 71.

Just as you can declare types for parameters, you can also specify what type a function should return. Return type declarations tell PHP exactly what kind of value your function will send back, helping catch errors when a function accidentally returns the wrong type.

To add a return type, place a colon followed by the type after the closing parenthesis of the parameter list:

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

echo add(5, 3);
?>

This outputs 8. The : int after the parentheses declares that this function must return an integer. If you tried to return a string instead, PHP would produce an error.

You can use the same types as parameter declarations: int, float, string, bool, and array. There's also a special type called void for functions that don't return anything:

<?php
function sayHello(string $name): void {
    echo "Hello, $name!\n";
}

sayHello("Alice");
?>

A void function cannot have a return statement with a value. Combining parameter types with return types makes your functions self-documenting—anyone reading the code immediately knows what goes in and what comes out.

Challenge

Easy

Read two lines of input:

A price as a decimal number (e.g., 49.99)
A discount percentage as a whole number (e.g., 20)

Create a function called calculateFinalPrice that accepts two parameters with type declarations:

$price as float
$discountPercent as int

The function must have a return type declaration of float and should return the final price after applying the discount.

Call the function with the input values and print the returned result.

Example 1:

If the inputs are 100.00 and 25, the output should be:

Example 2:

If the inputs are 49.99 and 10, the output should be:

44.991

Example 3:

If the inputs are 200.50 and 50, the output should be:

100.25

Try it yourself

<?php
// Read input
$price = floatval(fgets(STDIN));
$discountPercent = intval(fgets(STDIN));

// TODO: Create a function called calculateFinalPrice with:
// - Parameter $price with float type declaration
// - Parameter $discountPercent with int type declaration
// - Return type declaration of float
// The function should return the final price after applying the discount


// Call the function and print the result
echo calculateFinalPrice($price, $discountPercent);
?>

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction to PHP

The PHP Language Hello World!Tags and Statements Comments The new line

4Comparison & Logical Operators

Comparison Operators Equality & Identity Logical Operators Part 1 Logical Operators Part 2 Recap - Simple Logic

7Arrays Part 2 - Associative

Intro to Associative Arrays Accessing Values by Key Modifying Values by Key Adding New Key-Value Pairs Check if Key Exists Recap - Key-Value Data Store

10Functions

Declaring & Calling Functions Function Parameters Returning Values Default Parameter Values Type Declarations for ParamsReturn Type DeclarationsVariable Scope Recap - Creating Reusable Code