Constructor method in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a constructor method in PHP?

A constructor method is a special function inside a class that runs automatically when a new object is created. It usually sets up initial values or states for the object.

beginner

How do you name a constructor method in PHP 7 and later?

You name the constructor method __construct(). This is a magic method that PHP calls automatically when creating an object.

beginner

What happens if you do not define a constructor in a PHP class?

If no constructor is defined, PHP creates the object without running any setup code automatically. You can still set properties later, but no automatic initialization happens.

beginner

Show a simple example of a PHP class with a constructor that sets a property.

Example:<br><pre>&lt;?php
class Car {
  public $color;
  public function __construct($color) {
    $this->color = $color;
  }
}
$myCar = new Car('red');
echo $myCar->color; // Outputs: red
?&gt;</pre>

beginner

Why use a constructor method instead of setting properties after creating an object?

Using a constructor ensures the object is ready to use immediately after creation. It helps avoid forgetting to set important properties and keeps code cleaner and safer.

What is the correct name for a constructor method in PHP 7+?

A __construct()

B constructor()

C init()

D start()

The magic method __construct() is the standard constructor name in PHP 7 and later.

When is a constructor method called?

A When a method is called

B When an object is created

C When a property is accessed

D When the script ends

The constructor runs automatically right after an object is created.

What keyword is used inside a constructor to refer to the current object?

A $this

B $self

C $current

D $obj

In PHP, $this refers to the current object inside class methods.

What happens if you create an object from a class without a constructor?

A The object cannot be created

B PHP throws an error

C The object is created without automatic setup

D The object runs a default constructor

Without a constructor, the object is created but no automatic initialization code runs.

Which of these is a good reason to use a constructor?

A To call static methods

B To delay object creation

C To delete the object

D To set initial property values automatically

Constructors help set up initial values so the object is ready to use immediately.

Explain what a constructor method is and why it is useful in PHP classes.

Think about what happens right after you create a new object.

Write a simple PHP class with a constructor that sets a property called 'name'.

Use __construct and $this->name = ...