Convert `List<string>` to comma-separated string

Question

Is there a fast way to convert List<string> to a comma-separated string in C#?

I do it like this but Maybe there is a faster or more efficient way?

List<string> ls = new List<string>();
ls.Add("one");
ls.Add("two");
string type = string.Join(",", ls.ToArray());

PS: Searched on this site but most solutions are for Java or Python

Nope, you're doing it right. Although I don't think you need to do ToArray(). — Yuck
– Yuck, Commented Dec 21, 2011 at 16:41
@Yuck It is needed to convert to string[] (Because I don't use .NET 4) — Ozkan
– Ozkan, Commented Dec 21, 2011 at 16:49
@Ozkan You should probably tag your question for the framework version you're working against then. I think you'll find most answers will assume you're using the latest release. — Yuck
– Yuck, Commented Dec 21, 2011 at 17:06

Jon Skeet · Accepted Answer · 2011-12-21 16:42:49Z

125

In .NET 4 you don't need the ToArray() call - string.Join is overloaded to accept IEnumerable<T> or just IEnumerable<string>.

There are potentially more efficient ways of doing it before .NET 4, but do you really need them? Is this actually a bottleneck in your code?

You could iterate over the list, work out the final size, allocate a StringBuilder of exactly the right size, then do the join yourself. That would avoid the extra array being built for little reason - but it wouldn't save much time and it would be a lot more code.

answered Dec 21, 2011 at 16:42

Jon Skeet

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1 Comment

Mahesh Over a year ago

string.Join(",",myList )

JKennedy · Accepted Answer · 2015-06-19 07:48:20Z

20

To expand on Jon Skeets answer the code for this in .Net 4 is:

string myCommaSeperatedString = string.Join(",",ls);

answered Jun 19, 2015 at 7:48

JKennedy

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Comments

Anthony Shaw · Accepted Answer · 2013-12-26 15:19:58Z

15

The following will result in a comma separated list. Be sure to include a using statement for System.Linq

List<string> ls = new List<string>();
ls.Add("one");
ls.Add("two");
string type = ls.Aggregate((x,y) => x + "," + y);

will yield one,two

if you need a space after the comma, simply change the last line to string type = ls.Aggregate((x,y) => x + ", " + y);

edited Dec 26, 2013 at 15:19

answered Dec 21, 2011 at 16:54

Anthony Shaw

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3 Comments

Dan J Over a year ago

@Ozkan Please test it, and let us know.

Anthony Shaw Over a year ago

actually, I hadn't checked. With only the two items in the List, no, they are equally as fast, but exploding it to 100,000 items, the Aggregate actually is far slower than string.Join. Good to know I guess. I've preferred Aggregate in the past, but I think I'll be moving to string.Join in the future

M Akin Over a year ago

And, I found this throws an exception if the list is empty

Salim Latif Waigaonkar · Accepted Answer · 2015-04-11 07:17:57Z

4

Follow this:

       List<string> name = new List<string>();   

        name.Add("Latif");

        name.Add("Ram");

        name.Add("Adam");
        string nameOfString = (string.Join(",", name.Select(x => x.ToString()).ToArray()));

edited Apr 11, 2015 at 7:17

answered Apr 11, 2015 at 7:04

Salim Latif Waigaonkar

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1 Comment

nwsmith Over a year ago

This can be simplified further. The ToArray and ToString are not necessary, and the following works: String nameOfString = String.Join(",", name.Select(x => x));

hitesh kumar · Accepted Answer · 2017-06-17 11:29:36Z

3

static void Main(string[] args)
{
   List<string> listStrings = new List<string>(){ "C#", "Asp.Net", "SQL Server", "PHP", "Angular"};
   string CommaSeparateString = GenerateCommaSeparateStringFromList(listStrings);
   Console.Write(CommaSeparateString);
   Console.ReadKey();
}

private static string GenerateCommaSeparateStringFromList(List<string> listStrings)
{
   return String.Join(",", listStrings);  
}

Convert a list of string to comma separated string C#.

answered Jun 17, 2017 at 11:29

hitesh kumar

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1 Comment

thewaywewere Over a year ago

While this code may answer the question, providing additional context regarding how and/or why it solves the problem would improve the answer's long-term value. Please read this how-to-answer for providing quality answer.

Bryan B · Accepted Answer · 2011-12-21 16:42:47Z

0

That's the way I'd prefer to see if I was maintaining your code. If you manage to find a faster solution, it's going to be very esoteric, and you should really bury it inside of a method that describes what it does.

(does it still work without the ToArray)?

answered Dec 21, 2011 at 16:42

Bryan B

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1 Comment

Ozkan Over a year ago

I can do string.Join only on Array's of strings. So it is necessary (because I don't use .NET 4

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