Parent keyword behavior in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the parent class method inside the child class.

PHP

<?php
class Base {
    public function greet() {
        echo "Hello from Base\n";
    }
}

class Child extends Base {
    public function greet() {
        [1]::greet();
    }
}

$child = new Child();
$child->greet();
?>

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

Aself

Bparent

Cstatic

Dthis

Attempts:

3 left

💡 Hint

Common Mistakes

Using self instead of parent to call the parent method.

Using this which refers to the current object, not the parent.

In PHP, the parent keyword is used to call a method from the parent class inside a child class.

2fill in blank

medium

Complete the code to override the constructor and call the parent constructor.

PHP

<?php
class Animal {
    public function __construct() {
        echo "Animal created\n";
    }
}

class Dog extends Animal {
    public function __construct() {
        [1]::__construct();
        echo "Dog created\n";
    }
}

$dog = new Dog();
?>

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

Aself

Bthis

Cstatic

Dparent

Attempts:

3 left

💡 Hint

Common Mistakes

Using self::__construct() which calls the current class constructor, causing recursion.

Forgetting to call the parent constructor.

To call the parent class constructor inside the child constructor, use parent::__construct().

3fill in blank

hard

Fix the error in calling the parent method inside a static method.

PHP

<?php
class ParentClass {
    public static function sayHello() {
        echo "Hello from Parent\n";
    }
}

class ChildClass extends ParentClass {
    public static function sayHello() {
        [1]::sayHello();
        echo "Hello from Child\n";
    }
}

ChildClass::sayHello();
?>

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

Aself

B$this

Cparent

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Using $this inside a static method causing an error.

Using self which calls the current class method, not the parent.

Inside a static method, use parent::method() to call the parent static method.

4fill in blank

hard

Fill both blanks to correctly call the parent method and access a parent property.

PHP

<?php
class Vehicle {
    protected static $type = "Vehicle";
    public function getType() {
        return $this->type;
    }
}

class Car extends Vehicle {
    public function getType() {
        echo [1]::getType();
        echo " is a car.";
    }
    public function showType() {
        echo [2]::$type;
    }
}

$car = new Car();
$car->getType();
$car->showType();
?>

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

Aparent

Bself

CVehicle

Dthis

Attempts:

3 left

💡 Hint

Common Mistakes

Using self instead of parent to call the parent method.

Using parent to access a non-static property causing an error.

Use parent::getType() to call the parent method and Vehicle::$type to access the protected property statically.

5fill in blank

hard

Fill all three blanks to override a method, call the parent method, and add extra behavior.

PHP

<?php
class Logger {
    public function log($msg) {
        echo "Log: $msg\n";
    }
}

class FileLogger extends Logger {
    public function log($msg) {
        [1]::log($msg);
        echo [2] . " - logged to file" . [3];
    }
}

$logger = new FileLogger();
$logger->log("Error occurred");
?>

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

Aparent

B$msg

C"\n"

Dself

Attempts:

3 left

💡 Hint

Common Mistakes

Using self instead of parent to call the parent method.

Forgetting to use the variable $msg in the echo statement.

Missing the newline character causing output to be on the same line.

Use parent::log($msg) to call the parent method, then echo the message variable $msg followed by a newline "\n".