LVN_ITEMCHANGED - CListCtrl

[sankar]

I have a Dialog Box "AAA" which consists of a command button ( let's say "DISPLAY" ). On clicking this button another dialog box "BBB" is displayed which consists of a CListctrl among others. Now, I wanted to catch a notification when ever the item is changed. So, I implemented the OnNotify (LVN_ITEMCHANGED,IDC_LISTCTRL, FnHandler) like this : void CClass :: OnItemCHanged(NMHDR* pNMHDR, LRESULT* pResult ) { NM_LISTVIEW* pNMListView = ( NM_LISTVIEW)pNMHDR; int len = 0; LPTSTR str; myListCtrl.GetItemText(pNMListView ->iItem, 2, str, len) *pResult = 0; } Now, Coming to my doubt, when i try to debug with the break point inside this function, I observe that it breaks when I click the button DISPLAY. why's this when I haven't changed the state of the item yet, also, the application crashes saying "User BreakPoint Exception" after teh GetItemText call. I do see an error saying that " HEAP ALLOCATION EXCEEDED". what's wrong in the whole issue. PL. explain. regards Sankar

[Michael Dunn]

Your bug is that you don't allocate any space to hold the text. You pass an uninitialized pointer (str). And you give the buffer length as 0. --Mike-- http://home.inreach.com/mdunn/ #include "buffy_sig"

[Michael Dunn]

when i try to debug with the break point inside this function, I observe that it breaks when I click the button DISPLAY. LVN_ITEMCHANGED gets sent whenever any property of an item changes, including when an item is added/deleted to/from the list. If you want to act only when the selection changes, compare the old and new states of the item (which are sent with the message) and act only if their LVIS_SELECTED bits are opposite. --Mike-- http://home.inreach.com/mdunn/ #include "buffy_sig"