Interface Basics

InterfaceBasics.cs

using System;

/* //Interface Basics//
 * 
 * Interfaces can contain properties, methods, delegates or events but ONLY the declarations. NOT implementations.
 * 
 * Interface members are public by default and DO NOT allow explicit access modifiers
 * 
 * Interfaces CANNOT contain fields
 * 
 * If a class or a struct inherits from an interface, it MUST provide implementation for all interface members
 * 
 * A class or struct can inherit from more than one interface at the same time
 * 
 * Interfaces can inherit from other interfaces. If using multiple interfaces, you MUST provide implementation for all interface members of the interface chain
 * 
 * You CANNOT create an instance of an interface, but an interface reference variable can point to a derived class object.
 *
 */

interface IPrint
{
    void Print();
}

interface IAlsoPrint
{
    void AlsoPrint();
}

public class PrintImpl : IPrint, IAlsoPrint //using multiple interfaces, all interface members must be implemented
{
    public void Print()
    {
        Console.WriteLine("IPrint interface Print method called");
    }

    public void AlsoPrint()
    {
        Console.WriteLine("IAlsoPrint interface AlsoPrint method called");
    }
}


public class Program
{
    public static void Main()
    {
        PrintImpl P = new PrintImpl();
        P.Print();
        P.AlsoPrint();

        //example of a class inheriting from an interface
        IPrint PP = new PrintImpl();
        PP.Print();


        Console.ReadKey();
    }
}