Is the keyword "virtual" optional or mandatory in a overridable method?

Question

In C #, why we don't have a compilation error even if we forget the keyword "Virtual" in a method of a base class, redefined in a derived class. I learnded that this keyword is mandatory to override a method
is not it ?

public class Mother
{
    public  void  Speak()
    {
        Console.WriteLine("Mother !");
    }
}
public class Son : Mother
{
    public  void Speak()
    {
        Console.WriteLine("Son!!");
    }
}

Should be :

public class Mother
{
    public virtual  void  Speak()
    {
        Console.WriteLine("Mother !");
    }
}
public class Son : Mother
{
    public  override void Speak()
    {
        Console.WriteLine("Son!!");
    }
}

Show some code. You're doing something wrong or you question just isn't clear enough. **Always include your code**. — rory.ap, Feb 21 '18 at 13:58
To override a method, the `override` keyword is mandatory not `virtual`. — Adrian, Feb 21 '18 at 13:59
The difference is that you hide the method if you omit the virtual keyword, and not override it. — Lennart, Feb 21 '18 at 13:59
You should have a compiler warning that you are hiding the base implementation. — Crowcoder, Feb 21 '18 at 13:59
@rory.ap its a warning (CS0108), maybe check your facts before correcting someone. — Crowcoder, Feb 21 '18 at 14:04

score 0 · Accepted Answer · answered Feb 21 '18 at 14:02

Basically, Virtual and Override works on dynamic binding. The dynamic binding will be decided at run-time Compiler doesn't know that which virtual method will override in the derived class. That why it doesn't give you an error. This will be decided at run-time. Which derived class will be using at run-time.

Is the keyword "virtual" optional or mandatory in a overridable method?

1 Answers1