Duplicates in a Arraylist

ArrayList is too old and try to avoid unless you are on .NET 1.1.

Method 1

list.Sort();<br />int i = 0;<br />while (i < list.Count - 1)<br />{<br />   if ((int)list[i] == (int)list[i + 1])<br />        list.RemoveAt(i);<br />   else<br />        ++i;<br />}

Method 2

ArrayList target = new ArrayList(list.ToArray().Distinct().ToArray());

This works only when you have System.Linq namespace imported.

If you use .NET 3.5, use HashSet(T) class. It will not allow duplicate entries to be created. For .NET 2.0 or later, use List(T) other than ArrayList.

:)