Win32 ListView - handle invalid after LVM_INSERTITEM - c++

Question

I have a problem a window handle (window class = WC_LISTVIEW) after calling
SendMessage(hListView_, LVM_INSERTITEM , 0, (LPARAM)&lvItem);
where
hListView_
is a handle to a list view window and
lvItem
is an LVITEM structure. The following code
std::cout << "Last error: " << GetLastError() << std::endl;
SendMessage(hListView_, LVM_INSERTITEM , 0, (LPARAM)&lvItem);
std::cout << "Last error: " << GetLastError() << std::endl;
prints
Last error: 0
Last error: 6
According to Win32 System Error Codes code 6 means ERROR_INVALID_HANDLE.
I create the LVITEM structure as follows:
// define a char-buffer
char szBuffer[256];
szBuffer[0] = '\0';
// create new list view item
LVITEM lvItem;
lvItem.cchTextMax = 256;
lvItem.mask = LVIF_TEXT;
lvItem.iItem = 0;
lvItem.stateMask = 0;
lvItem.state = 0;
lvItem.iSubItem = 0;
snprintf(szBuffer, 256, "%s", myString.c_str());
lvItem.pszText = szBuffer;
This code is called from the same thread which created the window (list view).
Also note that I have
lvItem.iSubItem = 0;
which is required according to LVM_INSERTITEM. The list view is empty prior to this call. Moreover, I can actually see the value being inserted in the list view (i.e. I can see the item in the list view in the GUI).
However, when I try to use the window handle after this the application crashes (no exception, just crashes).
Greatful for any hints on what might cause this.
Thank you.

Answer 1

Thank you David Heffernan for your help. I did at last find the problem, which was (as you suggested) in a different place in the code.
I had missed the following line (in a different function which I call prior to the code I posted above)
lvItem.pszText = szBuffer;
where
char szBuffer[256]; // char-buffer
when doing the follwing call
SendMessage(hListView_, LVM_GETITEMTEXT, (WPARAM) i, (LPARAM) &lvItem);
Thanks a lot for your help!
Edit: If I had done
lvItem.pszText = myString.c_str();
rather than the char-buffer this would probably not have happened, so thanks for that hint!

Answer 2

There's no reason for you to call GetLastError. The documentation for LVM_INSERTITEM doesn't say that you should do so. All it says is that SendMessage returns the index of the new item on success, and -1 on failure. So, check for errors by inspecting the value returned by SendMessage.
The other problem is that you are not initialising all the fields of LVITEM. That's always a mistake. You can use an initialising declaration like this:
LVITEM lvItem = { 0 };
There's no real need for a separate buffer for the text. You can do it all like this:
LVITEM lvItem = { 0 };
lvItem.mask = LVIF_TEXT;
lvItem.cchTextMax = myString.length() + 1;
lvItem.pszText = myString.c_str();
int indexOfNewItem = SendMessage(hListView_, LVM_INSERTITEM, 0, (LPARAM)&lvItem);
if (indexOfNewItem == -1)
// deal with failure
It's quite possible that your error lies elsewhere in fact. I don't see any particular reason for that SendMessage call to lead to an application crash. At least now you know how to check for errors when sending LVM_INSERTITEM. If that does not result in an error then the evidence would be that the crash is caused by some other code and you have mistakenly identified this code because you erroneously called GetLastError when its value was meaningless.