Question

Ok, this looks ugly 🙂 What is a good way to refactor this block of code?

Users is data which is entered on the screen, and for this example we want distinct result in the _someDTOObject.Users

string[] userNames = Users.Split(new char[] { ',' });
string tempUserStr = "";
foreach (string user in userNames)
{
    tempUserStr += user.Trim().ToUpper() + ",";
}

userNames = tempUserStr.Split(new char[] { ',' });
var uniqueUsers = userNames.Distinct().ToList();

foreach (string user in uniqueUsers)
{
    if (!string.IsNullOrEmpty(user))
    {
        _someDTOObject.Users += user + ",";
    }   
}

Answer 1

It looks like you probably want something like:

_someDTOObject.Users = string.Join(",", Users.Split(',')
                                             .Select(x => x.Trim().ToUpper())
                                             .Distinct());

… but it’s not clear to me why you’re going through split/join/split to start with…

Note: if you’re using .NET 3.5, you’ll need an extra ToArray call after Distinct. You don’t on .NET 4, as the set of string.Join overloads has been increased.

(As noted in StriplingWarrior’s answer, this won’t have a trailing comma. Did you want a trailing comma?)