Method with same name and signature but different return type in C#

Question

I had an interview where I was asked the following:

Question: A method with same name and signature but different return type. Is it possible and what is this type c

Answer 1

In C#, you cannot have methods like

int Foo() { return 1; }

void Foo() { return; }

They must vary by more than return type.

If the arguments are different, then you're good to go.

int Foo(string x) { return 1; }

void Foo(double x) { return; }

Answer 2

Though return type covariance is not supported in C#, it is possible to emulate it by using explicit implementation and method hiding. That is a pattern which is used thoroughly in the ADO.NET APIs.

E.g.:

public interface ISomeValue { }
public abstract class SomeValueBase : ISomeValue { }
public class SomeValueImpl : SomeValueBase { }

public interface ISomeObject { ISomeValue GetValue(); }

public abstract class SomeObjectBase : ISomeObject
{
    ISomeValue ISomeObject.GetValue() { return GetValue(); }
    public SomeValueBase GetValue() { return GetValueImpl(); }

    protected abstract SomeValueBase GetValueImpl();
}

public class SomeObjectImpl : SomeObjectBase
{
    protected override SomeValueBase GetValueImpl() { return GetValue(); }
    public new SomeValueImpl GetValue() { return null; }
}

By doing that, the net result of calling GetValue() is that it will always match the most specific available type.

Answer 3

You can do it whit interface

   public interface IMyInterface
{
    int Metoda1()enter code here`;
}
public class MyClass : test.IMyInterface
{
    public IMyInterface Metoda1()
    {
        return new MyClas();
    }
    int test.IMyInterface.Metoda1()
    {
        return 1;
    }
}
   static void Main(string[] args)
    {
        MyClass instance = new MyClass();
        IMyInterface inst = instance.Metoda1();
     /*   IMyInterface ints2 = inst.Metoda1(); //will not compile*/
        Console.WriteLine(inst.GetType().ToString()); ;
        object inst3 = inst.Metoda1();
        Console.WriteLine(inst3.GetType().ToString());
    }