As an added benefit, using MFC and CWinApp enables you to use CCommandLineInfo just like in any other MFC app. You almost always want to parse the command line for parameters in a command line application, so CCommandLineInfo is extremely useful here. CCommandLineInfo is easy to derive from and apply - and anyway, deriving from and using a (popular) framework always beats rolling your own code, however trivial, in respect of readability/maintainability etc.

Notes:
- CWinApp doesn't mind you not having a main window (m_pMainWnd == NULL).
- The code compiles with Visual C++ 4.2 or later, with _CONSOLE and _AFXDLL.
- The code below will actually compile 'as is'.

Program example:

#include <afxwin.h>

#if !defined(_CONSOLE)
   #error Make it a console application project
#endif

/////////////////////////////////////////////////////////////////////////////
// DECLARE_CONSOLEAPP - enables MFC-like console app

#ifdef _CONSOLE
   #define DECLARE_CONSOLEAPP \
      extern int AFXAPI AfxWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,LPTSTR lpCmdLine, int nCmdShow);\
      extern "C" int _tmain( int /*argc*/, TCHAR** /*argv*/, TCHAR** /*envp*/)\
      {\
         return AfxWinMain(GetModuleHandle(NULL), NULL, GetCommandLine(), SW_SHOW);\
      }
      // remember to instantiate app class
#endif // _CONSOLE

/////////////////////////////////////////////////////////////////////////////
// Interface of CMyCommandLineInfo

class CMyCommandLineInfo : public CCommandLineInfo
{
// Attributes
public:
   BOOL    m_bHelp;        // /H /? /HELP
   CString m_strParameter;
   BOOL    m_bSuccess;     // all switches ok

// Construction
public:
   CMyCommandLineInfo(void);

// Overrides
public:
   virtual void ParseParam( LPCTSTR lpszParam, BOOL bFlag, BOOL bLast );
};

/////////////////////////////////////////////////////////////////////////////
// Implementation of CMyCommandLineInfo

CMyCommandLineInfo::CMyCommandLineInfo(void) : CCommandLineInfo(), m_bHelp(FALSE), m_bSuccess(TRUE)
{
}

void CMyCommandLineInfo::ParseParam(LPCTSTR lpszParam, BOOL bSwitch, BOOL /*bLast*/)
{
   if (bSwitch)
   {
      if (0 == lstrcmpi(_T("help"), lpszParam))
      {
         m_bHelp = TRUE;
      }
      else
      {
         // the for loop enables 'compound' switches like "/XYZ"
         BOOL bContinue = TRUE;
         for(int i = 0; (i < lstrlen(lpszParam)) && m_bSuccess && bContinue; i++)
         {
            switch(lpszParam[i])
            {
               case _T('?'):
               case _T('h'):
               case _T('H'):
                  m_bHelp = TRUE;
                  break;
               default:
                  m_bSuccess = bContinue = FALSE;
                  break;
            }
         }
      }
   }
   else
   {
      m_strParameter = lpszParam;
   }
}

/////////////////////////////////////////////////////////////////////////////
// Interface of some application class

class CMyApp : public CWinApp
{
// Construction
public:
   CMyApp(void);

// Attributes
public:
   CMyCommandLineInfo m_cmdInfo;

// Overrides
   // ClassWizard generated virtual function overrides
   //{{AFX_VIRTUAL(CMyApp)
   public:
   virtual BOOL InitInstance();
   virtual int Run();
   virtual int ExitInstance();
   //}}AFX_VIRTUAL

// Implementation
public:
   virtual ~CMyApp(void);
};

/////////////////////////////////////////////////////////////////////////////
// Instatiate the application class

DECLARE_CONSOLEAPP

CMyApp theApp;

/////////////////////////////////////////////////////////////////////////////
// Implementation of the application class

CMyApp::CMyApp(void) : CWinApp()
{
}

CMyApp::~CMyApp(void)
{
}

BOOL CMyApp::InitInstance()
{
   if (!CWinApp::InitInstance())
   {
      return FALSE;
   }

   _tprintf(_T("Init\n"));

   SetRegistryKey(_T("Codeguru samples"));

   ParseCommandLine(m_cmdInfo);

   return TRUE;
}

int CMyApp::Run()
{
   if (!m_cmdInfo.m_bSuccess)
   {
      _tprintf(_T("Bad command line\n"));
   }
   if (m_cmdInfo.m_bHelp || (!m_cmdInfo.m_bSuccess))
   {
      _tprintf(_T("usage: [ \"string\" /?]\n"));
   }
   else
   {
      m_cmdInfo.m_strParameter;
      _tprintf(_T("Run\n"));
      // ...
   }
   return CWinApp::Run(); // calls ExitInstance and exits right away when m_pMainWnd=NULL
}

int CMyApp::ExitInstance()
{
   _tprintf(_T("Done\n"));
   return CWinApp::ExitInstance();
}

Date Last Updated: February 3, 1999

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