Why inheritance is needed in PHP - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of PHP inheritance example

What will be the output of the following PHP code demonstrating inheritance?

PHP

<?php
class Animal {
    public function sound() {
        return "Some sound";
    }
}

class Dog extends Animal {
    public function sound() {
        return "Bark";
    }
}

$dog = new Dog();
echo $dog->sound();
?>

A Some sound

B Fatal error: Cannot redeclare method

C Bark

D No output

💡 Hint

Look at which class method is called when using the Dog object.

The Dog class inherits from Animal but overrides the sound() method. So calling sound() on a Dog object outputs 'Bark'.

🧠 Conceptual

intermediate

Why use inheritance in PHP?

Why is inheritance needed in PHP programming?

A To reuse code and create a hierarchy of classes

B To make code run faster by skipping functions

C To prevent any class from being used more than once

D To avoid writing any functions in classes

💡 Hint

Think about how inheritance helps avoid repeating code.

Inheritance allows a class to reuse code from another class and organize related classes in a hierarchy, making code easier to maintain and extend.

🔧 Debug

advanced

Identify the error in this inheritance code

What error will this PHP code produce?

PHP

<?php
class Vehicle {
    public function start() {
        echo "Vehicle started";
    }
}

class Car extends Vehicle {
    public function start() {
        echo "Car started";
    }
}

$car = new Vehicle();
$car->start();
?>

A Outputs 'Car started'

B Fatal error: Call to undefined method

C Fatal error: Cannot instantiate abstract class

D Outputs 'Vehicle started'

💡 Hint

Check which class is instantiated and which method is called.

The object is created from Vehicle class, so calling start() outputs 'Vehicle started'. No error occurs.

📝 Syntax

advanced

Which code correctly defines inheritance in PHP?

Which of the following PHP code snippets correctly shows inheritance?

A class Child inherits Parent {}

B class Child extends Parent {}

C class Child : Parent {}

D class Child -> Parent {}

💡 Hint

Remember the keyword PHP uses for inheritance.

PHP uses the keyword 'extends' to indicate inheritance between classes.

🚀 Application

expert

How many methods does the object have access to?

Given the following PHP code, how many methods can the $sportsCar object call?

PHP

<?php
class Vehicle {
    public function start() { return "Vehicle started"; }
    public function stop() { return "Vehicle stopped"; }
}

class Car extends Vehicle {
    public function openDoor() { return "Door opened"; }
}

class SportsCar extends Car {
    public function turboBoost() { return "Turbo boost activated"; }
}

$sportsCar = new SportsCar();
?>

A 4

B 3

C 2

D 5

💡 Hint

Count all methods from SportsCar and its parent classes accessible to the object.

The $sportsCar object can call start(), stop() from Vehicle, openDoor() from Car, and turboBoost() from SportsCar, totaling 4 methods.