Q169947: HOWTO: DDX - DDV for 64-Bit Numbers

Article: Q169947
Product(s): Microsoft C Compiler
Version(s): winnt:4.2b,5.0,6.0
Operating System(s): 
Keyword(s): kbMFC KbUIDesign kbVC420 kbVC500 kbVC600 kbDSupport kbGrpDSMFCATL
Last Modified: 17-JUL-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2b 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2b 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SUMMARY
=======

DDX - DDV functions in MFC do not directly support the __int64 type. However,
you can add your own functions to allow 64-bit numbers to be used with Edit
controls.

MORE INFORMATION
================

Below is sample code for DDX - DDV routines to handle the __int64 type. This
code can be easily modified to handle unsigned 64-bit numbers. This code uses
the TCHAR datatype for text so it works with Unicode or standard character types
without modification.

Sample Code
-----------

     // First we have to fix a bug in TCHAR.H.
     // _ttoi64 is incorrectly defined in TCHAR.H, so we need to undefine it
     // and redefine it correctly to avoid the compile error when building
     // and non-Unicode version.

     #ifdef _UNICODE
       #ifdef  _ttoi64
         #undef  _ttoi64
         #define _ttoi64 _wtoi64
       #endif
     #else
       #ifdef  _ttoi64
         #undef  _ttoi64
         #define _ttoi64 _atoi64
       #endif
     #endif

     //----------------------------------------------------------------------
     //  Use _ttoi64 and _i64tot to get the data into and out of the
     //  the member variables. These map to _atoi64 /_wtoi64 and
     //  _i64toa / _i64tow.
     // 
     void DDX_I64Txt( CDataExchange* pDX,
                      int            nIDC,
                      __int64&       nValue
                    )
     {
       TCHAR        szBuffer[32];
       HWND   hWndCtrl = pDX->PrepareEditCtrl(nIDC);

       if (pDX->m_bSaveAndValidate)
       {                                 // _int64 is 19 characters long
         *szBuffer = NULL;               // when converted to text.
         ::GetWindowText( hWndCtrl, szBuffer, 30 );
         nValue = _ttoi64( szBuffer );
       }
       else
       {
         _tcscpy( szBuffer, _i64tot( nValue, szBuffer, 10 ) );
         ::SetWindowText( hWndCtrl, szBuffer );
       }
     } // end DDX_I64Txt

                   //--------------------------------------------------------
  ------------
     //  Most DDV functions pass nValue by value. We pass a reference
     //  here so we can set the value to the min or max specified if
     //  an out-of-range value is passed in.
     // 
     void DDV_MinMaxI64( CDataExchange* pDX,
                         __int64&       nValue,
                         __int64        nMinVal,
                         __int64        nMaxVal
                       )
     {
       ASSERT( nMinVal <= nMaxVal);
       if( !pDX->m_bSaveAndValidate )
       {
     TRACE0("Warning: initial dialog data is out of range.\n");
     return;
       }

       if( (nValue < nMinVal) || (nValue > nMaxVal) )
       {
         TCHAR  szMinStr[32];          // Have to use strings here because
         TCHAR  szMaxStr[32];          // CString and sprintf formatting
         TCHAR  szMsgStr[64];          // don't support 64-bit numbers.
         _i64tot( nMinVal, szMinStr, 10 );
         _i64tot( nMaxVal, szMaxStr, 10 );
         _stprintf( szMsgStr, "Enter a value between %s and %s\n",
                    szMinStr, szMaxStr );
         AfxMessageBox( szMsgStr, MB_ICONEXCLAMATION );
                                       // Set the value to something defined
         (nValue < nMinVal) ? nValue = nMinVal : nValue = nMaxVal;

         pDX->Fail();                  // Restores focus to the
                                       // offending control and throws
       }                               // a user exception.
     } // End DDV_MinMaxI64.

Additional query words:

======================================================================
Keywords          : kbMFC KbUIDesign kbVC420 kbVC500 kbVC600 kbDSupport kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:4.2b,5.0,6.0
Issue type        : kbhowto

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