C / C++ / MFC

   afx_msg void OnMDIActivate(BOOL bActivate, CWnd* pActivateWnd, CWnd* pDeactivateWnd);

BEGIN_MESSAGE_MAP(CWinCTestFrame, [baseClass])
   //{{AFX_MSG_MAP(CWinCTestFrame)
   ON_WM_MDIACTIVATE()
   .
   .
   .
   //}}AFX_MSG_MAP
END_MESSAGE_MAP()
 
void CWinCTestFrame::OnMDIActivate(BOOL bActivate, CWnd* pActivateWnd, CWnd* pDeactivateWnd)
{
   CMultiFrame_base::OnMDIActivate(bActivate, pActivateWnd, pDeactivateWnd);
   if (bActivate)
      TRACE("ChildFrame - I'm Activated!\n");();
}

void AFXAPI DDX_Check(CDataExchange* pDX, int nIDC, int& value)
{
   HWND hWndCtrl = pDX->PrepareCtrl(nIDC);
   if (pDX->m_bSaveAndValidate)
   {
      value = (int)::SendMessage(hWndCtrl, BM_GETCHECK, 0, 0L);
      ASSERT(value >= 0 && value <= 2);
   }
   else
   {
      if (value < 0 || value > 2)
   {
   		TRACE1("Warning: dialog data checkbox value (%d) out of range.\n",
   			 value);
   		value = 0;  // default to off
   	}
   	::SendMessage(hWndCtrl, BM_SETCHECK, (WPARAM)value, 0L);
   }
}

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

CString strText = _T("abcde");<br />
<br />
long lLength = strText.GetLength();<br />
<br />
ASSERT(sizeof(TCHAR) == 2);<br />
ASSERT(lLength == 5);

...str.GetLength() * sizeof(TCHAR);

"One must learn from the bite of the fire to leave it alone." - Native American Proverb

void CString::ReleaseBuffer(int nNewLength)
{
   CopyBeforeWrite();  // just in case GetBuffer was not called

   if (nNewLength == -1)
      nNewLength = lstrlen(m_pchData); // zero terminated

   ASSERT(nNewLength <= GetData()->nAllocLength);
   GetData()->nDataLength = nNewLength;
   m_pchData[nNewLength] = '\0';
}