abstract interface

using System;

interface IAdd

{

int Add(int a, int b);

}

interface IMinus

{

int Minus(int a , int b);

}

abstract class abMethod

{

public int Add(int a, int b)

{

int tot = a+b;

return tot;

}

public abstract int Minus(int a, int b);

}

class NewInter : IAdd , IMinus

{

public int Add(int a, int b)

{

int add= a+b;

return add;

}

public int Minus(int a, int b)

{

int m = a-b;

return m;

}

}

class ABtest : abMethod

{

public override int Minus(int a, int b)

{

int m= a-b;

return m;

}

}

class Maintest

{

public static void Main()

{

Console.WriteLine("interface");

NewInter inter = new NewInter();

Console.WriteLine("Add(3,4)=>"+inter.Add(3,4));

Console.WriteLine("Minus(3,4)=>"+inter.Minus(3,4));

Console.WriteLine("abstract");

abMethod ab = new ABtest();

Console.WriteLine("Add(3,4)=>"+ab.Add(3,4));

Console.WriteLine("Minus(3,4)=>" + ab.Minus(3, 4));

}

}