Constructor basics PHP oops

• By Admin
• Jan 05, 2019

In Php OOPS, Constructor is a special member function which is created by the __construct() keyword.

__construct() is automatically called when we create instance of the class.

__construct() is a “Magic” Method used to define a Constructor.

The first method of any class is “Constructor method“.

__construct() can take  multiple parameters.

Example 1:

<?php

    class Animal
	{    
        private $name;
		
	    // constructor definition
		public function __construct($animal_name)
		{
			$this->name = $animal_name;
		}
	}
	
	$animal = new Animal("Indian Tiger");
	echo $animal->name;
	
?>

------------ ****** ------------

OUTPUT:
        Indian Tiger

Example 2:

<?php

		class BaseClass {
				
			public static $a=10;
				
			public function __construct() {
				  
				  echo "Calling parent class constructor"."<br>";
			  }
		}
			
		class SubClass extends BaseClass {
				
			  public function __construct($a) {
				  
				  echo "Calling child class constructor value = ".$a."<br>";
			  }
		}
			
		class SubClass1 extends SubClass {
				
			  public function __construct($a,$b) {
				  echo "Calling child class 1 constructor ".$a."======".$b."<br>";
			  }
			 
		}
		
		$obj1 = new SubClass1(2,5);

?>

------------ ****** ------------

OUTPUT:
         Calling child class 1 constructor “2”======”5
		 
		 

Note : If we want to called “Parent Class Constructor” in child class ,then we can achieved it by parent keyword followed by Scope Resolution operator(::).

i.e :  parent ::__construct().

<?php

		class BaseClass {
				
			public static $a=10;
				
			public function __construct() {
				  
				  echo "Calling parent class constructor"."<br>";
				  
			  }
		}
			
		class SubClass extends BaseClass {
				
			  public function __construct() {
			  
				  // Call to parent class constructor
				  parent::__construct();
				  echo "Calling child class constructor"."<br>";
				  
			  }
		}
		
		$obj = new BaseClass();
		$obj1 = new SubClass();
		
?>

------------ ****** ------------

OUTPUT:
          Calling parent class constructor.
		  Calling parent class constructor.
		  Calling child class constructor.