CDECL和_cdecl有什么不同以及为什么使用变参和_stdcall不出错？

[sagegz]

CDECL是个宏，在哪定义的？和_cdecl一样？
难道是这样?
#define CDECL _cdecl

#include <windows.h>
#include <tchar.h>  
        
int _stdcall MessageBoxPrintf (TCHAR * szCaption, TCHAR * szFormat, ...)	//使用_stdcall不出错？
        
{        
    TCHAR   szBuffer [1024];        
    va_list pArgList;   
    // The va_start macro (defined in STDARG.H) is usually equivalent to:
    // pArgList = (char *) &szFormat + sizeof (szFormat) ;
    va_start (pArgList, szFormat) ;
    // The last argument to wvsprintf points to the arguments
    _vsntprintf ( szBuffer, sizeof (szBuffer) / sizeof (TCHAR),
          szFormat, pArgList) ;
    // The va_end macro just zeroes out pArgList for no good reason   
    va_end (pArgList) ;     
    return MessageBox (NULL, szBuffer, szCaption, 0) ;     
}
        
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                   PSTR szCmdLine, int iCmdShow) 
{    
    int cxScreen, cyScreen ;   
    cxScreen = GetSystemMetrics (SM_CXSCREEN);
    cyScreen = GetSystemMetrics (SM_CYSCREEN);
    MessageBoxPrintf (TEXT ("ScrnSize"),
		TEXT ("The screen is %i pixels wide by %i pixels high."),
        cxScreen, cyScreen) ;  
    return 0 ;    
}

[Eleven]

#if defined(DOSWIN32) || defined(_MAC)
#define cdecl _cdecl
#ifndef CDECL
#define CDECL _cdecl
#endif
#else
#define cdecl
#ifndef CDECL
#define CDECL
#endif
#endif

http://topic.csdn.net/u/20110318/15/591ac68c-238d-473a-b06d-0446c557ac35.html