Why cant we have multiple class inheritance in C#?

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Multiple inheritance using interfaces as mentioned below is possible to achieve both the properties of A and B classes to AB class.

interface IA
  { void Print(); }
  interface IB
  { void Print(); }

  class A : IA
  {
      public void Print()
      { Console.WriteLine("ClassA"); }
  }

  class B : IB
  {
      public void Print()
      { Console.WriteLine("ClassB"); }
  }

  class AB : IA, IB
  {
      void IA.Print()
      {
          A a = new A();
          a.Print();
      }

      void IB.Print()
      {
          B b = new B();
          b.Print();
      }
  }

  class Test
  {
      public void test()
      {
          AB ab = new AB();
          ((IA)ab).Print();
          ((IB)ab).Print();
      }
  }

Then why cant we have multiple class inheritance as mentioned below.

class A
{
    public void Print()
    { Console.WriteLine("ClassA"); }
}

class B
{
    public void Print()
    { Console.WriteLine("ClassB"); }
}

class AB : A, B
{

}

class Test
{
    public void test()
    {
        AB ab = new AB();
        ((A)ab).Print();
        ((B)ab).Print();
    }
}

As far i know C# wont support multiple class inheritance because it can not decide which method to call when both the base classes are having same method signature.

Then it can be overcome by having code something like above.

I am aware of the diamond problem which also can solve similar to above way.

am i missing to understand something here?
Or it is just like C# doesn't implement this kind of functionality without any reason?

What I have tried:

I tried to understand by reading the available articles in internet

Posted 29-Mar-18 7:56am

Ved_deV

Updated 29-Mar-18 9:33am

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OriginalGriff · Answer 1 · 2018-03-29T08:11:00

First off, Interfaces don't provide multiple inheritance: interfaces are not classes, they are a contract, and you can't "inherit" from an interface.

As to why C# doesn't support MI, the most likely reasons is "because the benefits do not overweigh the complexity involved in implementing it" - and the main reason for that complexity is the Diamond Problem: Multiple inheritance - Wikipedia[^]

The diamond problem arises when two classes B and C inherit from A, and another class D also inherits from both B and C. If a method in D calls a method defined in A, and B and C have overridden that method, then which class method should be executed? the version from B, or the version from C?

Although it is possible to get round this (C++ does) it complicates the language and the code you write - and C# is designed to encourage clean, simple, and maintainable code (an accusation not often leveled at C++ code!).

Wendelius · Answer 2 · 2018-03-29T08:05:00

Unfortunately C# does not support multiple inheritance. You can read more from Why doesn’t C# support multiple inheritance? | C# Frequently Asked Questions[^]

However, depending on the situation there are ways to overcome this restriction. For example in many cases extending a class with extension method does the trick. Have a look at Extension Methods (C# Programming Guide) | Microsoft Docs[^]

CPallini · Answer 3 · 2018-03-29T09:35:00

Solution 3

Because it ~~is a toy language~~ doesn't support it.

Posted 29-Mar-18 9:35am

CPallini

Comments

Wendelius 29-Mar-18 15:44pm

Biased, are we? :)

CPallini 29-Mar-18 15:59pm

Who, me? :-)

Why cant we have multiple class inheritance in C#?

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