Question

I want to create an interface that implements some of its own methods in Java (but the language won’t allow this, as shown below):

//Java-style pseudo-code
public interface Square {
    //Implement a method in the interface itself
    public int getSize(){//this can't be done in Java; can it be done in C++?
        //inherited by every class that implements getWidth()
        //and getHeight()       
        return getWidth()*getHeight();
    }
    public int getHeight();
    public int getWidth();
}

//again, this is Java-style psuedocode
public class Square1 implements Square{

    //getSize should return this.getWidth()*this.getHeight(), as implemented below

    public int getHeight(){
        //method body goes here
    }

    public int getWidth{
        //method body goes here
    }
}

Is it possible to create the equivalent of an interface in C++ that can implement some of its own methods?

Answer 1

To answer your other question, yes it can be done in C++ through the use of the virtual keyword. To my knowledge, it is the primary method of polymorphism in C++.

This set of tutorials is great; I would recommend a solid read-through if you want to learn more about C/C++.