Problem of struct default constructor in vc++2005 beta1

Problem of struct default constructor in vc++2005 beta1

• new2C#

  	3512.1
  	I made a default constructor for a struct as below. But this caused a compliation error in vc++ 2005:   --------------------------------------------------------------------- Error 1  error C3417: 'Point :: Point' : value types cannot contain user-defined special member functions --------------------------------------------------------------------- the code was copied from a book of vc++ .net 2003. I got this error in VC++ 2005. any idea --------------------------------------------------------------------- #include "stdafx.h" using namespace System; value struct Point { public:  int x, y;  Point(){x=0;y=0;} }; int _tmain() {  return 0; }

  
  

• Andrea Ramacciotti

  This is a limitation of the CLR, now enforced by VC++ 2005:  Value types (structs) cannot have "special member functions".  The CLR requires that value types be initialized by setting all members to zero and requires them to be memcpy-able.
  
  In your example, that's exactly what your constructor is doing - just get rid of the constructor since the CLR is doing exactly that initialization for you.  If you need a constructor that doesn't simply initialize to zero, you'll need to create a factory function (or property).
  
  value struct Point
  {
  public:
   int x, y;
   static Point At(int x_, int y_)
   {
      Point p;   // inits to all 0's
      p.x = x_;
      p.y = y_;
      return p;
   }
  };
  
  
  
  

• neo1

  NNTP User, I don't quite understand what you said. C++/CLI is not Mircorsoft C++
  
  I am reading a book called 'microsoft visual C++ .net step by step version 2003'. The program was copied from that book. parameterless constructor of value type is supposed to work in vc++2003, if what in the book is correct.
  
  is it a new feature of vc++2005
  
  thx
  

• KrisFB_APPS

  Riekey wrote:

  NNTP User, I don't quite understand what you said. C++/CLI is not Mircorsoft C++

  
  
  C++/CLI is not MC++ meaning Managed Extensions for C++.  VC 2005 essentially uspports three different dialects of C++:
  
  1. ISO 14882 standard C++ (also known as native C++)
  2. Managed Extensions for C++ (introduced with VC7/2002).  This is the original syntax for interacting with .NET from C++.
  3. C++/CLI (introduced with VC8/2005).  This is the new syntax for .NET in C++.
  
  

  Riekey wrote:

  I am reading a book called 'microsoft visual C++ .net step by step version 2003'. The program was copied from that book. parameterless constructor of value type is supposed to work in vc++2003, if what in the book is correct.

  
  
  The example may be assuming that you're writing native (ISO standard) C++, not managed C++. 
  
  You control which dialect you're compiling using the /clr command line argument (or the related options in the IDE).
  
  /clr not included - native code
  /clr : oldSyntax - Managed Extensions for C++
  /clr - C++/CLI (may contain a mixture of managed and native code)
  /clr : pure - C++/CLI (pure managed code, no embedded native code)
  /clr : safe - C++/CLI (verifiable only)
  
  (remove spaces between /clr : option - added to prevent emoticon recognition)
  
  
• Problem of struct default constructor in vc++2005 beta1