• Resizeable, unordered, index-based collection.
• Suffers from boxing/unboxing when working with value types.
• Implements IEnumerator, allowing foreach operations.
  • The IEnumerator is a .NET implementation of the Iterator Pattern.

• When possible, use a generic collection instead of the object-based ArrayList.

ArrayList a = new ArrayList();
a.Add(16);
a.AddRange(new object[] { "Hello", "World" });
a.Insert(0, "Start");
a.InsertRange(2, new int[] { 32, 64 });
foreach (var o in a) { Console.WriteLine(o); }
 
a.Remove("Hello");
a.RemoveAt(1);
a.RemoveRange(1, 2);
foreach (var o in a) { Console.WriteLine(o); }

ArrayList a = new ArrayList();
a.AddRange(new object[] { "Hello", "World" });
Console.WriteLine(a.Contains("World") ? "World Found" : "World Missing");