Using PHP7 Type Declarations to Improve Code Readability

PHP 7 introduced strong type declarations, allowing developers to specify exact data types for function parameters and return values, which improves code readability and reduces debugging effort.

Function parameter type declarations replace manual type checks with built‑in validation. The following example shows a function that declares its parameters as integers:

<code>function calculateTotal(int $price, int $quantity): int {
    return $price * $quantity;
}

$total = calculateTotal(10, 5);
echo "Total: $total";
</code>

Because calculateTotal expects $price and $quantity as integers, PHP automatically converts compatible values and throws a TypeError for mismatched types, making the code clearer.

Function return type declarations let developers define the expected return type. The example below declares a boolean return type:

<code>function isEven(int $number): bool {
    return $number % 2 == 0;
}

$result = isEven(6);
if ($result) {
    echo "The number is even";
} else {
    echo "The number is odd";
}
</code>

Here the function isEven guarantees a boolean result, preventing accidental return‑type errors and improving reliability.

Nullable type declarations use a leading ? to indicate that a parameter or return value may be of the specified type or null . The following code demonstrates a function that may return an array or null :

<code>function getUser(string $username): ?array {
    // Retrieve user from database; return null if not found
    $user = getUserFromDatabase($username);
    return $user ?: null;
}

$user = getUser("john");
if ($user) {
    echo "Username: {$user['username']}";
} else {
    echo "User not found";
}
</code>

By declaring the return type as ?array , the function clearly communicates that callers must handle the possibility of a null value.

Summary – Using PHP 7 type declarations—parameter, return, and nullable—significantly enhances code readability, reduces redundant type‑checking code, prevents type‑related bugs, and improves overall maintainability for backend developers.