What is type hinting and how does it work?

Type hinting is a mechanism for defining and restricting data types of parameters in functions or methods in many modern object-oriented programming languages, including PHP. It allows programmers to specify the expected type for a parameter or the type of value returned from a function, making the code clearer, aiding in error detection, and improving code readability.

In PHP, type hinting can be used for scalar types (introduced in PHP 7.0) as well as for classes or interfaces. To use type hinting for function or method parameters, you simply specify the expected type after a colon following the parameter name. Here's an example:

                        
class Car {
    public $model;

    public function setModel(string $model) {
        $this->model = $model;
    }

    public function getModel(): string {
        return $this->model;
    }
}

$car = new Car();
$car->setModel("Toyota");

echo $car->getModel(); // Outputs "Toyota"
                        
                    

In this example, `setModel` takes a `$model` parameter, which must be a string. Thus, you specify the expected data type using type hinting.

If the data type of the parameter does not match the specified type, PHP may throw an error during program execution. Type hinting also allows using the `null` type if you need to permit passing `null` when the type is not defined or not relevant.