C# List to String

Last modified May 14, 2025

This tutorial demonstrates how to convert a List to a string in C#.

To convert a list of elements into a single string in C#, we can use the string.Join method, StringBuilder class, Enumerable.Aggregate method, or the string concatenation operator.

The string.Join method combines elements of a collection or array, inserting a specified separator between each element. The StringBuilder class efficiently builds strings dynamically. The Enumerable.Aggregate method applies an accumulator function across a sequence of values.

C# uses the + operator to concatenate strings, though this can be less efficient for large lists.

Using string.Join

The following example uses the string.Join method to convert a list into a string.

List<string> words = ["a", "visit", "to", "London"];
var res = string.Join("-", words);

Console.WriteLine(res);

This example creates a slug from a list of words by joining them with hyphens. This method is efficient even for large lists because it allocates the result string only once.

$ dotnet run
a-visit-to-London

Using StringBuilder

This example demonstrates the use of the StringBuilder class to build a string from a list.

using System.Text;

List<string> words = ["There", "are", "three", "chairs", "and", "two",
    "lamps", "in",  "the", "room"];

var builder = new StringBuilder();

foreach (var word in words)
{
    builder.Append(word).Append(' ');
}

Console.WriteLine(builder.ToString());

The code iterates through the list using a foreach loop, appending each word and a space to a StringBuilder object. The ToString method converts the result to a string. This approach is very efficient for large lists due to the mutable nature of StringBuilder.

$ dotnet run
There are three chairs and two lamps in the room

Using Enumerable.Aggregate

The next example employs the Enumerable.Aggregate method to convert a list to a string.

List<string> words = ["There", "are", "three", "chairs", "and", "two", 
    "lamps", "in",  "the", "room"];

var res = words.Aggregate((total, part) => $"{total} {part}");
Console.WriteLine(res);

This example uses string interpolation within the accumulator function to build the string by concatenating each word with a space. While convenient, Aggregate is less efficient than StringBuilder or string.Join for large lists.

Using String Concatenation

This example uses the string concatenation operator to build a string from a list.

List<string> words = ["There", "are", "three", "chairs", "and", "two", 
    "lamps", "in",  "the", "room"];

string res = string.Empty;

words.ForEach(word => {

    res += $"{word} ";
});

Console.WriteLine(res);

The code iterates over the list using the ForEach method, appending each word and a space to the result string using the += operator. This approach is simple and easy to understand. However, repeated string concatenation can be inefficient for large lists. For large lists, this method is not recommended due to performance overhead.

Using string.Concat

Another way to convert a list to a string is to use the string.Concat method. This method concatenates all elements of the list without any separator. It is a quick way to join list elements when no delimiter is needed. This method is efficient for combining many strings together.

List<string> words = ["There", "are", "three", "chairs", "and", "two", 
    "lamps", "in",  "the", "room"];

var res = string.Concat(words);
Console.WriteLine(res);

This example uses string.Concat to join all elements of the list into a single string without any separator. If you need a separator, use string.Join instead. This method is efficient for large lists as it allocates the result string only once.

Source

string.Join method

This tutorial has demonstrated various methods to convert a list to a string in C#.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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