Question

If you are given an array with random prefixes, like this:

DOG_BOB
CAT_ROB
DOG_DANNY
MOUSE_MICKEY
DOG_STEVE
HORSE_NEIGH
CAT_RUDE
HORSE_BOO
MOUSE_STUPID

How would i go about sorting this so that i have 4 different arrays/lists of strings?

So the end result would give me 4 string ARRAYS or lists with

DOG_BOB,DOG_DANNY,DOG_STEVE <-- Array 1
HORSE_NEIGH, HORSE_BOO <-- Array 2
MOUSE_MICKEY, MOUSE_STUPID <-- Array 3
CAT_RUDE, CAT_ROB <-- Array 4

sorry about the names i just made them up lol

var fieldNames = typeof(animals).GetFields()
                    .Select(field => field.Name)
                    .ToList();
List<string> cats = new List<string>();
List<string> dogs = new List<string>();
List<string> mice= new List<string>();
List<string> horse = new List<string>();
foreach (var n in fieldNames)
{
    var fieldValues = typeof(animals).GetField(n).GetValue(n);"

    //Here's what i'm trying to do, with if statements
    if (n.ToString().ToLower().Contains("horse"))
    {
    }
}

So i need them to be splitted into STRING ARRAYS/STRING LISTS and NOT just strings

Answer 1

string[] strings = new string[] { 
                      "DOG_BOB",
                      "CAT_ROB",
                      "DOG_DANNY",
                      "MOUSE_MICKEY",
                      "DOG_STEVE",
                      "HORSE_NEIGH",
                      "CAT_RUDE",
                      "HORSE_BOO",
                      "MOUSE_STUPID"};

string[] results = strings.GroupBy(s => s.Split('_')[0])
                          .Select(g => String.Join(",",g))
                          .ToArray();

Or maybe something like this

List<List<string>> res = strings.ToLookup(s => s.Split('_')[0], s => s)
                                 .Select(g => g.ToList())
                                 .ToList();