Re: error C2371: 'WCHAR' : redefinition; different basic types

From:

"Doug Harrison [MVP]" <dsh@mvps.org>

Newsgroups:

microsoft.public.vc.mfc

Date:

Tue, 31 Jul 2007 12:13:44 -0500

Message-ID:

<c2rua3dp7mn1oj4errn0hb4fer5ht78chi@4ax.com>

On Tue, 31 Jul 2007 07:48:49 -0700, Alex Y Wang <redflyingpig@gmail.com>
wrote:

Hi all, I've been haunted by this problem for quite a while. I've done
a lot of search on the internet but haven't found any solution to
this. I'm building an MFC program with ODBC support and got the
following error:

c:\program files\microsoft visual studio 8\vc\platformsdk\include
\odbcss.h(430) : error C2371: 'WCHAR' : redefinition; different basic
types
c:\program files\microsoft visual studio 8\vc\platformsdk
\include\winnt.h(266) : see declaration of 'WCHAR'

In odbcss.h I found

#ifdef UNICODE
...
#else
typedef char DBCHAR;
#endif

In ocdb.h I found

#if !defined(OLE2ANSI)

#define LPDBSTR LPWSTR
#define DBCHAR WCHAR
...

And in winnt.h I found

#ifndef _MAC
typedef wchar_t WCHAR; // wc, 16-bit UNICODE character
...

Which seems to be a bug to me. I've seen this issue being raised many
times during my search but none of them is fully answered.

What were the solutions you found?

Is there a
suggested solution to this at all?

It would be immensely helpful if you were to present a set of #includes
that demonstrate your problem, such as:

// Just as an example...
#include <windows.h>
#include <odbcss.h>

Then I could try it at the command line with something like "cl -c a.cpp".
If I were to guess, I'd say it may an order problem; the Windows headers
can be finicky that way.

--
Doug Harrison
Visual C++ MVP