Join together all items of a list in an output string in .NET

Question

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

Example

IList<string> data = new List<string>();  data.Add("MyData1"); data.Add("MyData2");  string result = // Some LINQ query... I try data.Select(x => x + ",");  //result = "MyData1, MyData2" 

Answer 1

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 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 one 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())