Type hinting with parent classes in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to type hint the parameter as the parent class.

PHP

<?php
class Animal {}
function feed([1] $animal) {
    echo "Feeding animal";
}
?>

Drag options to blanks, or click blank then click option'

ABird

BDog

CCat

DAnimal

Attempts:

3 left

💡 Hint

Common Mistakes

Using a child class name instead of the parent class for type hinting.

The parameter should be type hinted as the parent class Animal to accept any subclass instance.

2fill in blank

medium

Complete the method signature to accept any subclass of Vehicle using type hinting.

PHP

<?php
class Vehicle {}
class Car extends Vehicle {}
function startEngine([1] $vehicle) {
    echo "Engine started";
}
?>

Drag options to blanks, or click blank then click option'

ACar

BVehicle

CEngine

DMotor

Attempts:

3 left

💡 Hint

Common Mistakes

Type hinting with a subclass instead of the parent class.

The method should accept the parent class Vehicle to allow any subclass like Car.

3fill in blank

hard

Fix the error by correctly type hinting the parameter to accept any subclass of Fruit.

PHP

<?php
class Fruit {}
class Apple extends Fruit {}
function eat([1] $fruit) {
    echo "Eating fruit";
}
?>

Drag options to blanks, or click blank then click option'

AFruit

BApple

CFood

DVegetable

Attempts:

3 left

💡 Hint

Common Mistakes

Using a subclass name which restricts accepted types.

Type hinting with the parent class Fruit allows the function to accept any subclass like Apple.

4fill in blank

hard

Fill both blanks to create a function that accepts any subclass of Device and calls its method.

PHP

<?php
class Device {
    public function powerOn() {
        echo "Device powered on";
    }
}
class Phone extends Device {}
function activate([1] $device) {
    $device->[2]();
}
?>

Drag options to blanks, or click blank then click option'

ADevice

BpowerOn

Cstart

DPhone

Attempts:

3 left

💡 Hint

Common Mistakes

Type hinting with a subclass or calling a method that does not exist.

The parameter should be type hinted as Device to accept any subclass. The method called is powerOn defined in the parent class.

5fill in blank

hard

Fill all three blanks to define a function that accepts any subclass of Employee, checks the role, and prints a message.

PHP

<?php
class Employee {
    public function getRole() {
        return "Employee";
    }
}
class Manager extends Employee {
    public function getRole() {
        return "Manager";
    }
}
function printRole([1] $emp) {
    if ($emp->getRole() === [2]) {
        echo [3];
    }
}
?>

Drag options to blanks, or click blank then click option'

AEmployee

B"Manager"

C"Manager role detected"

DManager

Attempts:

3 left

💡 Hint

Common Mistakes

Using subclass name as type hint or incorrect string literals.

The function parameter is type hinted as Employee to accept any subclass. It compares the role string to "Manager" and prints the message "Manager role detected".