////////////////////////////////////////////////////////////////
// MSDN Magazine — November 2004

// To compile:
//   cl /clr VirtFnTest.cpp
//
#include <stdio.h>
#include <vcclr.h>
#using <mscorlib.dll>

using namespace System;

/////////////////
// C++ native base class. Ctor calls virtual fn: always calls Base fn.
class Base {
public:
   Base()
   {
      printf(" Base::ctor\n");
      Hello();
   }
   ~Base()
   {
      printf(" Base::dtor\n");
      Goodbye();
   }
   virtual void Hello()   { printf(" Base::Hello\n"); }
   virtual void Goodbye() { printf(" Base::Goodbye\n"); }
};

// Derived native C++ class overrides fn, but not called from ctor.
class Derived : public Base {
public:
   Derived()
   {
      printf(" Derived::ctor\n");
   }
   ~Derived()
   {
      printf(" Derived::dtor\n");
   }
   virtual void Hello()   { printf(" Derived::Hello\n"); }
   virtual void Goodbye() { printf(" Derived::Goodbye\n"); }
};

// Managed base class. Ctor calls virtual fn: always calls most derived 
// override.
public __gc class MBase {
public:
   MBase() {
      printf(" Base::ctor\n");
      Hello();
   }
   ~MBase() {
      printf(" Base::dtor\n");
      Goodbye();
   }
   virtual void Hello()   { printf(" Base::Hello\n"); }
   virtual void Goodbye() { printf(" Base::Goodbye\n"); }
};

// Managed derived class overrides virtual fn.
public __gc class MDerived : public MBase {
public:
   MDerived()
   {
      printf(" Derived::ctor\n");
   }
   ~MDerived()
   {
      printf(" Derived::dtor\n");
   }
   virtual void Hello()   { printf(" Derived::Hello\n"); }
   virtual void Goodbye() { printf(" Derived::Goodbye\n"); }
};

int main()
{
   printf("Create native object:\n");
   Derived *pd = new Derived();
   printf("Destroy native object:\n");
   delete pd;

   printf("\nCreate managed object:\n");
   MDerived *pmd = new MDerived();
   printf("Destroy managed object:\n");
   delete pmd; // force dtor call
   return 0;
}

Figure 3 Pod.cpp
　

/////////////////////////////////////////////////////////////////////
// You can embed native POD types in a managed (__gc or __value) type.
// Compile with cl /clr.

#using <mscorlib.dll>

// simple struct is a POD type
struct POINT {
   int x;
   int y;
};

// native class w/ctor: not POD!
class CPoint : public POINT {
   CPoint() { x=y=0; }
};

// Managed __gc type
__gc class Circle {
public:
   POINT center;        // ok: embedded POD type
   CPoint m_center;     // Error: not POD!
   int radius;
};