C / C++ / MFC

void LogAuditMessage(DWORD nThreadID, LPCSTR szfmt, ...)
{  
  va_list args;
  va_start(args, szfmt);
  
  static bool bCheckDone(false);
  if (!bCheckDone)
  {
    // now check to see if todays date directory exist YYMMDD
    SYSTEMTIME Current;
    GetLocalTime(&Current);
    
    strcpy(m_cDateFormat, "");	
    sprintf(m_cDateFormat, "%04d%02d%02d", Current.wYear, Current.wMonth, Current.wDay);
    
    // create the main directory, if it does not exist
    if (!FileExists(".\\Audit\\."))
      _mkdir(".\\Audit");
    
    bCheckDone = true;
  }
  
  char sBuff[100] = "";
  sprintf(sBuff, ".\\Audit\\%s.log", m_cDateFormat);
  
  // Write to the logging file
  FILE* f;
  
  char szBuf[1024];
  char cTimeBuff[50] = "";
  _strtime(cTimeBuff);
  
  _vsnprintf(szBuf, 1024, szfmt , args);
  va_end(args);
  
  f = _tfopen(_T(sBuff), _T("a"));
  if (f != NULL)
  {
    _ftprintf(f, _T("%08x, %s, %s\n"), nThreadID, cTimeBuff, szBuf);
    fclose(f);
  }  
}