LINQ to find array indexes of a value

Question

Assuming I have the following string array:

string[] str = new string[] {\"max\", \"min\", \"avg\", \"max\", \"avg\", \"min\"}

Is it possbile t

Answer 1

You can use the overload of Enumerable.Select that passes the index and then use Enumerable.Where on an anonymous type:

List result = str.Select((s, index) => new { s, index })
                      .Where(x => x.s== "avg")
                      .Select(x => x.index)
                      .ToList();

If you just want to find the first/last index, you have also the builtin methods List.IndexOf and List.LastIndexOf:

int firstIndex = str.IndexOf("avg");
int lastIndex = str.LastIndexOf("avg");

(or you can use this overload that take a start index to specify the start position)