Inheriting the same method from multiple interfaces

Question

That we know multiple (interface) inheritance is allow in c# but, I want to know is it possible that two interface Example :

 interface calc1
{
    int addsub(int a, int b);
}
interface calc2
{
    int addsub(int x, int y);
}

with same method name with same type and with same type of parameter

will get inherit in above class ?

class Calculation : calc1, calc2
{
    public int result1;
    public int addsub(int a, int b)
    {
        return result1 = a + b;
    }
    public int result2;
    public int addsub(int x, int y)
    {
        return result2= a - b;
    }
}

if yes then which interface method will get called.

Thanks in advance.

Answer 1

You can't overload the method like that, no - they have the same signatures. Your options are:

• Use one implementation, which will be called by both interfaces

• Use explicit interface implementation for one or both of the methods, e.g.

  int calc2.addsub(int x, int y)
  {
      return result2 = a - b;
  }
  

  If you do that for both methods, neither method will be callable on a reference of type Calculation; instead, you'd have to cast to one interface or the other before calling the method, including within the class. For example:

  public void ShowBoth()
  {
      Console.WriteLine(((calc1)this).addsub(5, 3)); // 8
      Console.WriteLine(((calc2)this).addsub(5, 3)); // 2
  }