Visual C++ .NET/Class/abstract class

Abstract classes

<source lang="csharp">

1. include "stdafx.h"

ref class MyClass abstract{

  int ID;
  public:
     virtual void ReadFromFile() abstract;
     virtual void UpdateID(int id){
         ID = id;
     }

}; ref class MySubClass : MyClass{

   public:
     virtual void ReadFromFile() override
     {
     }

};

 </source>

Abstract sealed class

<source lang="csharp">

1. include "stdafx.h"

using namespace System; ref class A abstract sealed {

  static int i = 1;
  static int j = 2;
  public:
    static A() { 
       Console::WriteLine("A::A()"); 
    }
    static void f() { 
       Console::WriteLine("A::f " + i); 
    }
    static void g() { 
       Console::WriteLine("A::g " + j); 
    }

}; int main() {

  A::f();
  A::g();

}

 </source>

Extends abstract class

<source lang="csharp">

1. include "stdafx.h"

using namespace System; ref class AbstractBaseClass abstract{ protected:

   int AbstractVar;
   AbstractBaseClass(int val): AbstractVar(val) {}

public:

   virtual void Method1() = 0;  // unimplemented method
   virtual void Method2() = 0;  
   void Method3()
   {
       Console::WriteLine(AbstractVar.ToString());
   }

}; ref class MidAbstractBaseClass abstract : public AbstractBaseClass { public:

   virtual void Method1() override sealed
   {
       Console::WriteLine((AbstractVar * 3).ToString());
   }

protected:

   MidAbstractBaseClass(int val) : AbstractBaseClass(val) {}

}; ref class DerivedExClass : public MidAbstractBaseClass { public:

   DerivedExClass(int val) : MidAbstractBaseClass(val) {}
   virtual void Method2() override
   {
       Console::WriteLine((AbstractVar * 2).ToString());
   }

}; void testMethod(AbstractBaseClass ^aec) {

   aec->Method1();
   aec->Method2();
   aec->Method3();

} void main() {

   AbstractBaseClass ^Ab1 = gcnew DerivedExClass(5);
   Ab1->Method1();
   Ab1->Method2();
   Ab1->Method3();
   AbstractBaseClass ^Ab2 = gcnew DerivedExClass(6);
   testMethod(Ab2);
   DerivedExClass ^dc = gcnew DerivedExClass(7);
   testMethod(dc);

}

 </source>