Interface Implementation

The interface can be implemented by a class or a struct as shown in this example:
class MyClass: IMyInterface1
{
    // class implementation
}
By this declaration the class MyClass is obligated to implement all members of the interface IMyInterface.
It is also possible for a class to implement more than one interface:
class MyClass: IMyInterface1, IMyInterface2
{
    //class implementation
}
A class can also implement another class in addition to the interfaces:
class MyClass: MyBaseClass, IMyInterface1, IMyInterface2
{
    //class implementation
}
In the following example, the class Point implements the interface the interface IPoint. Notice that all the fields are included in the class but none are included in the interface.
//Example 8-1.cs
//Interface example
using System;
interface IPoint
{
    //Property signatures:
    int Myx
    {
        get; set;
    }
    int Myy
    {
        get; set;
    }
}
class Point: IPoint
{
    //Fields:
    private int x;
    private int y;
    //constructor:
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    //Property implementation:
    public int Myx
    {
        get { return x; }
        set { x = value; }
    }
    public int Myy
    {
        get  { return y; }
        set ( y = value; }
    }
    public static void DisplayMyPoint(IPoint myPoint)
    {
        Console.WriteLine(“({0},{1}”, myPoint.Myx, myPoint.Myy);
    }
}
class MyClass
{
    static void Main()
    {
        Point myPoint = new Point(12,300);
        Console.Write(“My point is created at: “);
        Point.DisplayMyPoint(myPoint);
    }
}

Notes about the preceding example:
I.    If we don’t implement all the members of the interface, we get a compilation error. Try commenting the properties (Myx and Myy) in the class to see the compiler error message.
II.    Notice also that it is possible to pass a parameter of the type IPoint to the method DisplayMyPoint. We can, of course, pass a parameter of the type Point instead.
III.    Notice also that it is possible to pass a parameter of the type IPoint to the method DisplayMyPoint. We can, of course, pass a parameter of the type Point instead.