LINQ

Reverse String
Reverse String in C# 
using System.Linq;

public static class ReverseString
{
    public static string Reverse(string input)
    {
        return new string(input.Reverse().ToArray());
    }
}

The string class implements the IEnumerable<char> interface, which allows us to call LINQ's Reverse() extension method on it.

To convert the IEnumerable<char> returned by Reverse() back to a string, we first use ToArray() to convert it to a char[].

Finally, we return the reversed string by calling its constructor with the (reversed) char[].

Shortening

There are two things we can do to further shorten this method:

  1. Remove the curly braces by converting to an expression-bodied method
  2. Use a target-typed new expression to replace new string with just new (the compiler can figure out the type from the method's return type)

Using this, we end up with:

public static string Reverse(string input) => new(input.Reverse().ToArray());

Performance

If you're interested in how this approach's performance compares to other approaches, check the performance approach.

20th Nov 2024 · Found it useful?

Other Approaches to Reverse String in C#

Other ways our community solved this exercise
var chars = input.ToCharArray();
Array.Reverse(chars);
return new string(chars);
Array.Reverse

Use Array.Reverse to reverse a string. 

Span<char> chars = stackalloc char[input.Length];
for (var i = 0; i < input.Length; i++)
{
    chars[input.Length - 1 - i] = input[i];
}
return new string(chars);
Span<T>

Use Span<T> and stack allocation for hyper-optimized string reversal. 

var chars = new StringBuilder();
for (var i = input.Length - 1; i >= 0; i--)
{
    chars.Append(input[i]);
}
return chars.ToString();
StringBuilder

Reverse a string using the StringBuilder class.