Convert a list of strings to a single string

Question

List<string> MyList = (List<string>)Session["MyList"];

MyList contains values like: 12 34 55 23.

I tried using the code below, however the values disappear.

string Something = Convert.ToString(MyList);

I also need each value to be separated with a comma (",").

How can I convert List<string> Mylist to string?

Possible duplicate of [Creating a comma separated list from IList or IEnumerable](https://stackoverflow.com/questions/799446/creating-a-comma-separated-list-from-iliststring-or-ienumerablestring) — Binke, Jul 17 '19 at 12:18

score 145 · Accepted Answer · answered Oct 13 '13 at 13:54

145

string Something = string.Join(",", MyList);

answered Oct 13 '13 at 13:54

ProgramFOX

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score 20 · Answer 2 · answered Oct 13 '13 at 13:56

20

Try this code:

var list = new List<string> {"12", "13", "14"};
var result = string.Join(",", list);
Console.WriteLine(result);

The result is: "12,13,14"

answered Oct 13 '13 at 13:56

MUG4N

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Sam · Answer 3 · 2014-08-13T14:29:28.870

Or, if you're concerned about performance, you could use a loop,

var myList = new List<string> { "11", "22", "33" };
var myString = "";
var sb = new System.Text.StringBuilder();

foreach (string s in myList)
{
    sb.Append(s).Append(",");
}

myString = sb.Remove(sb.Length - 1, 1).ToString(); // Removes last ","

This Benchmark shows that using the above loop is ~16% faster than String.Join() (averaged over 3 runs).

Falgantil · Answer 4 · 2013-12-19T10:09:20.063

8

Entirely alternatively you can use LINQ, and do as following:

string finalString = collection.Aggregate("", (current, s) => current + (s + ","));

However, for pure readability, I suggest using either the loop version, or the string.Join mechanism.

edited Dec 19 '13 at 10:09

answered Oct 13 '13 at 14:12

Falgantil

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Could you elaborate on the syntax? Am I correct in assuming the first argument to be the return string, which will be concatenated with the second argument? What are the variables `current `and `s` exactly, current string and current value? – Wouter Vanherck May 27 '20 at 09:17

score 6 · Answer 5 · answered Oct 13 '13 at 13:59

You can make an extension method for this, so it will be also more readable:

public static class GenericListExtensions
{
    public static string ToString<T>(this IList<T> list)
    {
        return string.Join(",", list);
    }
}

And then you can:

string Something = MyList.ToString<string>();

score 2 · Answer 6 · answered Jul 17 '19 at 12:08

2

I had to add an extra bit over the accepted answer. Without it, Unity threw this error:

cannot convert `System.Collections.Generic.List<string>' expression to type `string[]'

The solution was to use .ToArray()

List<int> stringNums = new List<string>();
String.Join(",", stringNums.ToArray())

answered Jul 17 '19 at 12:08

modle13

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This shouldn't have happened as [string.Join](https://learn.microsoft.com/en-us/dotnet/api/system.string.join?view=net-5.0#System_String_Join_System_String_System_Collections_Generic_IEnumerable_System_String__) works on `IEnumerable`s, which both `List` and `Array` are. – Bip901 Dec 20 '20 at 16:52

Convert a list of strings to a single string

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