May 19th, 2013 at 12:42 AM

abstract and virtual methods in C#

Virtual methods have an implementation and provide the derived classes with the option of overriding it. Abstract methods do not provide an implementation and force the derived classes to override the method.

public abstract class E
{
    public abstract void AbstractMethod(int i);

    public virtual void VirtualMethod(int i)
    {
        // Default implementation which can be overridden by subclasses.
    }
}

public class D : E
{
    public override void AbstractMethod(int i)
    {
        // You HAVE to override this method
    }
    public override void VirtualMethod(int i)
    {
        // You are allowed to override this method.
    }
}