How to convert a List to a string in C#

Using String.Join()

String.Join() is one of the easiest ways to convert a List to a string. By providing a delimiter, you can generate a single string that separates the items. Below is an example where a List<string> is converted to a string using a comma as the delimiter:

var list = new List<string>()
{
    "Alice", "Bob", "Charlie", "Dave", "Eve"
};

string names = String.Join(",", list);

Console.WriteLine(names);

This will output:

Alice,Bob,Charlie,Dave,Eve

Notice that String.Join() ensures there’s no trailing comma at the end.

You can use String.Join() with any type of list, as it calls ToString() on each item internally.

Here’s an example where a List<int> is converted to a string, with each number on a new line:

var list = new List<int>()
{
    10, 20, 30, 40, 50
};

string numbers = String.Join(Environment.NewLine, list);

Console.WriteLine(numbers);

This will output the integers as a newline-separated string:

10
20
30
40
50

Using StringBuilder and a foreach Loop

Another method to convert a List to a string is by using a foreach loop in combination with a StringBuilder. This method gives you more control over the process and allows you to manipulate the string more flexibly.

Here’s an example where we convert a List<string> to a comma-separated string using a loop and StringBuilder:

using System.Text;

var list = new List<string>()
{
    "Tom", "Jerry", "Spike"
};

var sb = new StringBuilder();
var delimiter = ",";

foreach(var name in list)
{
    sb.Append(name);
    sb.Append(delimiter);
}

// Remove the trailing delimiter
if (sb.Length > 0)
    sb.Remove(sb.Length - 1, 1);

string result = sb.ToString();

Console.WriteLine(result);

This will output:

Tom,Jerry,Spike

As you can see, the trailing comma is removed after the loop by using StringBuilder.Remove(). This approach avoids the need to conditionally append the delimiter during the loop, making the code more efficient.

• String.Join() is great for simplicity and works well for basic cases with a consistent delimiter.
• StringBuilder with a loop is a bit more flexible and allows for fine-tuning, like removing trailing delimiters.