没有合适的方法来覆盖c＃，尽管有一个？

Question

I was trying to find a solution here about this issue and I also feel my problem is very small but I cannot figure out what is going wrong. It is telling me Rectangle.draw(): no suitable method found to override.

    public interface shape 
    {
        void draw();
    }

    //concrete classes that implemenet interfaces
    public class Rectangle : shape 
    {
        public override void draw()
        {
            Console.WriteLine(this.GetType().Name + "'s inside function (generate stuff here) ");
        }
    }

Answer 1

The error is correct. You can only override a method if it is present in an inherited base class. Your Rectangle class doesn't inherit anything; it only implements the interface "shape".

Remove the "override" keyword and everything will be fine.

Answer 2

The behavior of C# is a bit confusing at this point, especially for someone with a C++ background. Although behind the scenes, an interface works almost the same as an abstract base class, C# doesn't call an interface implementation an override. This has one advantage: For each method, you can specify whether child classes can override the interface implementation or not. If you specify virtual when implementing your draw method, a class square that inherits from rectangle can implement its own draw method, if you specify nothing, square could not override draw. The later is helpful if you are forwarding calls to some (protected) method of the class only.