Why does this C# code compile fine when there is an ambiguous virtual method?

Question

I have a class (Class B) that inherits another class (Class A) that contains virtual methods.

Mistakenly, I omitted the override keyword when declaring a (supposed to be) overriding method in Class B.

Class A

public class ClassA{
    public virtual void TestMethod(){
    }
}

Class B

public class ClassB : ClassA{
    public void TestMethod(){
    }
}

The code compiled without a problem. Can anyone explain why?

Answer 1

class B should be

public class ClassB : ClassA{
    public override void TestMethod(){
    }
}

but it can compile without the override - it should generate a warning that if it was intended you need to add the new keyword

public class ClassB : ClassA{
    public new void TestMethod(){
    }
}

checkout this for more information

Answer 2

It's not ambiguous. It should compile with a warning to say that you should either specify "new" or "override" and that the default is effectively "new".

It definitely gives a warning when I try to compile that code - when you say it compiles "fine" and "without a problem" are you ignoring warnings?

Answer 3

The C# compiler generates a warning. I advice you to always compile with 'warnings as errors'.