DOCUMENT:Q169947  17-JUL-2001  [visualc]
TITLE   :HOWTO: DDX - DDV for 64-Bit Numbers
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:4.2b,5.0,6.0
OPER/SYS:
KEYWORDS:kbMFC KbUIDesign kbVC420 kbVC500 kbVC600 kbDSupport kbGrpDSMFCATL

======================================================================
-------------------------------------------------------------------------------
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 
-------------------------------------------------------------------------------

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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