Are there pure virtual functions in PHP like with C++

Question

I would have thought lots of people would have wondered whether this is possible but I can\'t find any duplicate questions... do correct me.

I just want to know whether

Answer 1

You can create abstract functions, but you need to declare the parent class as abstract, too:

abstract class Parent {
   // no implementation given
   abstract public function foo();
}

class Child extends Parent {
   public function foo() {
      // implementation of foo goes here
   }
}

Answer 2

There are abstract classes!

abstract class Parent {
   // no implementation given
   abstract public function foo();
   }
}

class Child extends Parent {
   public function foo() {
      // implementation of foo goes here
   }
}

Answer 3

Declare the method as abstract in the Parent class:

abstract public function foo();

Answer 4

Yes, that type of solution is possible, it's called polymorphism, you can do it without declaring an abstract class or an interface.