Array Indexes

[charindal]

i would like some help on how to retrieve array indexes. i have the following scenario:

List <string> alphabet = new ....;

alphabet.add("a ");
alphabet.add("b ");
alphabet.add("a ");
alphabet.add("c ");
alphabet.add("a ");

i have populated a new arraylist which only identifies distinct/unique alphabet items in the firt array e.g. it is able to list contents a, b and c only.

my challenge is how do i identify occurence index for the unique array list so that it displays and shows that
item "a" exists on index 0,2,4
item "b" exists on index 1
item "c" exists on index 3

thank you..

[adwenger0066]

public int[] indexesOf(List list, String string) {
  List<int> result = new List<int>();
  for (int i = 0; i < list.Count; i++) { 
   if (list[i] == string) {
        result.Add(i);
   }
  }
  return result.ToArray();
}