Abstract Class

Sample

abstract class absClass1
{
    public abstract int AddTwoNumbers(int Num1, int Num2);
    public abstract int MultiplyTwoNumbers(int Num1, int Num2);
}

abstract class absClass2 : absClass1
{
    public override int AddTwoNumbers(int Num1, int Num2)
    {
        return Num1+Num2;
    }
}

class absDerived : absClass2
{
    public override int MultiplyTwoNumbers(int Num1, int Num2)
    {
        return Num1*Num2;
    }
}

Note:

• You need to use the override keyword when you override a method.