.Net - Join together all item of a list in a output string

Question

How can I write a Linq expression (or anything else) that select item from a List and join them together ?

Example

IList data = new List<         


        

Answer 1

You can use aggregate when you need to join a list into a single aggregated object.

string s = "";
if(data.Count > 0)
  s = data.Aggregate((a, b) => a + ',' + b);

Answer 2

You may be tempted to use Aggregate() if you're sticking with LINQ

IList<int> data = new List<int>();

data.Add(123);
data.Add(456);

var result = data.Select(x => x.ToString()).Aggregate((a,b) => a + "," + b);

I wouldn't recommend this because as I found out the hard way this will fail if the list contains zero items - or was it if it had only 1 item. I forget, but it fails all the same :-)

String.Join(...) is the best way

In the example above where the datatype is NOT a string you can do this :

string.Join(",", data.Select(x => x.ToString()).ToArray())

Answer 3

Why not just go with (String.Join Method)

string joined = String.Join(",", data.ToArray());

But if it has to be LINQ, you could try

string joinedLinq = data.Aggregate((i, j) => i + "," + j);

Answer 4

As Anthony Pegram wrote String.Join<T>(delimiter, IEnumerable<T>) is the best solution in .NET 4!