Interview Questions and Answers - Object Orient Programming in PHP (OOP) - Intermediate

Question. No. 1:

What are magic methods ?

Answer:

• __construct : called while initializing an object with a "new" keyword
• __destruct : when object is going out of scope.
• __call : When method doesn't exists or access restricted in Object scope
• __callStatic : When method doesn't exists or access restricted in Static Scope
• __get : when trying to read a variable which doesn't exist or access restricted
• __set: when trying to set a variable which doesn't exist or access restricted
• __isset : when trying to check isset a variable which doesn't exist or access restricted
• __unset : when trying to unset a variable which doesn't exist or access restricted
• __sleep :  when serialize an object in order to store in database 

class myClass

{

       var $var1 = 3; 

private $var2 = 2;

    public function __sleep()

    {

        return array('var1', 'var2');

    }

}

$myObj= new myClass;

serialize($myObj);

• __wakeup : when un-serialize an object get serialize object then un-serialize it 

class myClass

{

       var $var1 = 3; 

private $var2 = 2;

    public function __wakeup ()

    {

        return array('var1', 'var2');

    }

}

$myObj= new myClass;

$se = serialize($myObj);

unserialize($se);

• __toString: when a class object was printed as string this method will be called

class myClass

{

    public function __toString()

    {

        return 'class name';

    }

}

$myObj = new myClass;

echo $myObj;

• __invoke : when declared ,it will be used as a callable function with instantiated object name. it takes same number of arguments passed.

class myClass

{

    public function __invoke($x,$y)

    {

        echo $x.$y;

    }

}

$myObj = new myClass;

$myObj (4,5);

• __set_state : when var_export() function called on the object

• __clone : when called clone on an object. when we try to tract the serials of cloned.
• __autoload : its not a method but Function,