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

Answer 1

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.

Answer 2

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);

Answer 3

要扩展Jon Skeets，请回答.Net 4的代码：

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

Answer 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()));

Answer 5

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#.

Answer 6

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)?