Retrieve the index of the selected item in a ListView in C#.

You can use the SelectedIndices property to obtain the index of the selected item in a ListView.

The example code is shown below:

int selectedIndex = listView1.SelectedIndices[0];

This will return the index value of the selected item and store it in the selectedIndex variable. Note that the SelectedIndices property returns a collection containing the indexes of all selected items, so we can get the index value of the first selected item by using index 0. If you want to get the index values of all selected items, you can use a loop to iterate through the SelectedIndices collection.