Use the ItemIndex property to determine the index number of the item in the Repeater control from the Items collection of the control.
Note
This property only applies to data items in the Repeater control. The ItemType property must be set to ListItemType.Item, ListItemType.AlternatingItem, ListItemType.SelectedItem, or ListItemType.EditItem.
The following example demonstrates how to use the ItemIndex property to display the index number of the item in the Repeater control from the Items collection of the control.