UNICOD issue

Hi, I'm pretty much new to windows programming.
I'm trying to write my own MessageBox function.So far I manage to do this:

Code:

#include <windows.h>
#include <stdio.h>
#include <tchar.h>

int __cdecl MyMessageBox (HWND hwnd,TCHAR * szCaption,UINT uType,const TCHAR * szFormat, ...)
{
     TCHAR szBuffer[1024];
	 va_list pArgList;
	 va_start(pArgList,szFormat);

	 _vsntprintf(szBuffer,sizeof(szBuffer)/sizeof(TCHAR),szFormat,pArgList);

	 return MessageBox(NULL,szBuffer,szCaption,0);
}

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow) 
{
     int x=5;
	 MyMessageBox(NULL,_T("Caption"),MB_OK,_T("%d"),x);
     return 0 ;
}

When I compile it and run it everything works fine, but if I do this:

Code:

#define UNICODE
#include <windows.h>
#include <stdio.h>
#include <tchar.h>

int __cdecl MyMessageBox (HWND hwnd,TCHAR * szCaption,UINT uType,const TCHAR * szFormat, ...)
{
     TCHAR szBuffer[1024];
	 va_list pArgList;
	 va_start(pArgList,szFormat);

	 _vsntprintf(szBuffer,sizeof(szBuffer)/sizeof(TCHAR),szFormat,pArgList);

	 return MessageBox(NULL,szBuffer,szCaption,0);
}

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow) 
{
     int x=5;
	MyMessageBox(NULL,_T("Caption"),MB_OK,_T("%d"),x);
     return 0 ;
}

I get compiler errors:
error C2664: '_vsnprintf' : cannot convert parameter 1 from 'TCHAR [1024]' to 'char *'

error C2664: 'MyMessageBox' : cannot convert parameter 2 from 'char [8]' to 'TCHAR *'

I manage to eliminate the second error by changing line:

Code:

MyMessageBox(NULL,_T("Caption"),MB_OK,_T("%d"),x);

to line:

Code:

MyMessageBox(NULL,TEXT("Caption"),MB_OK,TEXT("%d"),x);

This is not what I expected because I found in header files something like this:

Code:

...
#define _T(x) L##x //tchar.h
...
#define _TEXT(quote) L##quote //winnt.h
...
#define TEXT(quote) __TEXT(quote)

I thought that _T and TEXT are equivalent, but it seems they aren't.
Anyway I was not be able to solve first error, so my program will not work if UNICODE is defined.
I tried to use preprocessor and to define _vsntprintf as
_vsnwprintf if UNICODE is defined, but failed.

So I have two question:
1. How to fix this errors so my program work with UNICODE defined
2. What is the difference between _T and TEXT.
I'm using .net and windows XP
Thank you very much!

1. #define_UNICODE and UNICODE
2. 2 extra characters of typing (ie. functionally, none).

Thanks dude!
So the key reason is to define _UNICODE
I made my program work before I read your post. I wrote this:

Code:

#define UNICODE
#include <windows.h>
#include <stdio.h>
#include <tchar.h>

#ifdef UNICODE
#undef _vsntprintf
#define _vsntprintf _vsnwprintf
#else
#define _vsntprintf _vsnprintf
#endif

int __cdecl MyMessageBox (HWND hwnd,TCHAR * szCaption,UINT uType,const TCHAR * szFormat, ...)
{
     TCHAR szBuffer[1024];
	 va_list pArgList;
	 va_start(pArgList,szFormat);
	 _vsntprintf(szBuffer,sizeof(szBuffer)/sizeof(TCHAR),szFormat,pArgList);

	 return MessageBox(NULL,szBuffer,szCaption,uType);
}

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow) 
{
     int x=5;
	 MyMessageBox(NULL,TEXT("Caption"),MB_OK,TEXT("%d"),x);
     return 0 ;
}

I know how silly this code looks now.
Thanks again!