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CListBox::CompareItem

Called by the framework to determine the relative position of a new item in a sorted owner-draw list box.

virtual int CompareItem(
   LPCOMPAREITEMSTRUCT lpCompareItemStruct 
);

Parameters

lpCompareItemStruct
A long pointer to a COMPAREITEMSTRUCT structure.

Return Value

Indicates the relative position of the two items described in the COMPAREITEMSTRUCT structure. It may be any of the following values:

Value Meaning
–1 Item 1 sorts before item 2.
0 Item 1 and item 2 sort the same.
1 Item 1 sorts after item 2.

See CWnd::OnCompareItem for a description of the COMPAREITEMSTRUCT structure.

Remarks

By default, this member function does nothing. If you create an owner-draw list box with the LBS_SORT style, you must override this member function to assist the framework in sorting new items added to the list box.

Example

// CMyListBox is my owner-drawn list box derived from CListBox. This 
// example compares two items using strcmp to sort items in reverse 
// alphabetical order. The list box control was created with the 
// following code:
//   pmyListBox->Create(
//      WS_CHILD|WS_VISIBLE|WS_BORDER|WS_HSCROLL|WS_VSCROLL|
//      LBS_SORT|LBS_MULTIPLESEL|LBS_OWNERDRAWVARIABLE,
//      myRect, pParentWnd, 1);
//
int CMyListBox::CompareItem(LPCOMPAREITEMSTRUCT lpCompareItemStruct) 
{
   ASSERT(lpCompareItemStruct->CtlType == ODT_LISTBOX);
   LPCTSTR lpszText1 = (LPCTSTR) lpCompareItemStruct->itemData1;
   ASSERT(lpszText1 != NULL);
   LPCTSTR lpszText2 = (LPCTSTR) lpCompareItemStruct->itemData2;
   ASSERT(lpszText2 != NULL);

   return strcmp(lpszText2, lpszText1);
}

See Also

CListBox Overview | Class Members | Hierarchy Chart | WM_COMPAREITEM | CWnd::OnCompareItem | CListBox::DrawItem | CListBox::MeasureItem | CListBox::DeleteItem

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