CListCtrl::MapIndexToID
Maps the index of an item in the current list-view control to a unique ID.
UINT MapIndexToID(
UINT index
) const;
Parameters
Parameter |
Description |
|---|---|
[in] index |
The zero-based index of an item. |
Return Value
A unique ID for the specified item.
Remarks
A list-view control internally tracks items by index. This can present problems because indexes can change during the control's lifetime. The list-view control can tag an item with an ID when the item is created. You can use this ID to access a specific item for the lifetime of the list-view control.
Note that in a multithreaded environment the index is guaranteed only on the thread that hosts the list-view control, not on background threads.
This method sends the LVM_MAPINDEXTOID message, which is described in the Windows SDK.
Requirements
Header: afxcmn.h
This control is supported in Windows Vista and later.
Additional requirements for this method are described in Build Requirements for Windows Vista Common Controls.
Example
The following code example defines a variable, m_listCtrl, that is used to access the current list-view control. This variable is used in the next example.
public:
// Variable used to access the list control.
CListCtrl m_listCtrl;
The following code example demonstrates the MapIndexToID method. In an earlier section of this code example, we created a list-view control that displays two columns titled "ClientID" and "Grade" in a report view. The following example maps the index of each list-view item to an identification number, and then retrieves the index for each identification number. Finally, the example reports whether the original indexes were retrieved.
// MapIndexToID
int iCount = m_listCtrl.GetItemCount();
UINT nId = 0;
UINT nIndex = 0;
for (int iIndexOriginal = 0; iIndexOriginal < iCount; iIndexOriginal++)
{
// Map index to ID.
nId = m_listCtrl.MapIndexToID((UINT)iIndexOriginal);
// Map ID to index.
nIndex = m_listCtrl.MapIDToIndex(nId);
if (nIndex != (UINT)(iIndexOriginal))
{
CString str;
str.Format(_T("Mapped index (%d) is not equal to original index (%d)"),
nIndex, (UINT)(iIndexOriginal));
AfxMessageBox(str);
return;
}
}
AfxMessageBox(_T("The mapped indexes and original indexes are equal."),
MB_ICONINFORMATION);