GetDlgItem() returns null in vc++ 2010

Question

I recently converted a visual studio 6.0 project to visual studio 2010 and I'm encountering an issue whenever calling GetDlgItem on certain items. The following code is failing.

CWnd *pWnd = (CWnd*) GetDlgItem(IDC_BATCH);
pWnd->GetWindowText(szBatchNum);

I see this code in my resource file for the form that's calling the above code.

IDD_CC_PROCESS DIALOGEX 0, 0, 657, 410
STYLE DS_SETFONT | WS_CHILD
FONT 8, "MS Sans Serif", 0, 0, 0x0
BEGIN
CONTROL         "",IDC_BATCH,"{978C9E23-D4B0-11CE-BF2D-00AA003F40D0}",0x0,85,18,89,16
END

After the call to GetDlgItem() pWnd is NULL. This was not an issue in the 6.0 version of the project. IDC_BATCH seems to be a valid resource on this form. IDC_BATCH points to a "Microsoft Forms 2.0 Label". This seems to be one of the many issues I've encountered while converting the project from 6.0 to 2010.

Answer 1

Try enumerating the child items of the CWnd from which the GetDlgItem call comes from, and see if the handle even has children. Also you should check the value returned by GetLastError, this should indicate if its an actual error, and what that error is, or if the control really has no children(which then might be an error in the res file) or if the parent control even exists

Answer 2

I don't have any particular knowledge on this issue, but I'd check if the GUID/control has been updated for the version of MFC which ships with VS2010. If the MFC version doesn't recognize the control type by GUID, it may not be able to correctly create the CWnd wrapper object for it. You may need to update the GUID for VS2010, and/or try using native Win32 calls to access it, rather than the MFC wrapper calls.

Hope that helps.