How to refer parent class properties, methods from sub class

There are two ways to refer parent class data from sub class.

a.   Using the class name directly.

Ex: ClassName::method_name(args)

b.   Using the keyword ‘parent’.

Ex: parent::method_name(args)

 

When can I call parent class methods?

If you override a static method in sub class, and if you want to call the parent class method explicitly, you can use this syntax.

 

parent_keyword_demo.php

#!/usr/bin/php

<?php

    class ParentClass{
       public static function about_me(){
           echo "\n\nI am in parent class";
       }
    }

    class ChildClass1 extends ParentClass{

        public static function about_me(){
            ParentClass::about_me();
            echo "\nI am in ChildClass1";
        }
    }

    class ChildClass2 extends ParentClass{
        public static function about_me(){
            parent::about_me();
            echo "\nI am in ChildClass2";
        }
    }

    ParentClass::about_me();
    ChildClass1::about_me();
    ChildClass2::about_me();

?>

 

Output

#!/usr/bin/php

<?php

    class ParentClass{
       public static function about_me(){
           echo "\n\nI am in parent class";
       }
    }

    class ChildClass1 extends ParentClass{

        public static function about_me(){
            ParentClass::about_me();
            echo "\nI am in ChildClass1";
        }
    }

    class ChildClass2 extends ParentClass{
        public static function about_me(){
            parent::about_me();
            echo "\nI am in ChildClass2";
        }
    }

    ParentClass::about_me();
    ChildClass1::about_me();
    ChildClass2::about_me();

?>

 

 

 

 

 

 

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