Find All Index
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Drawing; using System.Drawing.Imaging; public static class CollectionsExtensions { public static List<int> FindAllIndex<T>(this List<T> container, Predicate<T> match) { var items = container.FindAll(match); List<int> indexes = new List<int>(); foreach (var item in items) { indexes.Add(container.IndexOf(item)); } return indexes; } }