Reverse a string in C#

In this article we will discuss Reverse a string in C#.

In this article we will not look at the Reverse method provided by the .NET libraries; we will instead try to implement it by our own logic. However we will be using the ToCharArray method in most of our examples.

Reversing a string is a popular question in most campus hiring interviews. There could be several ways one can think of to do this.

1st Way

Using Two Arrays - One to store the input and another for the output and uses two variables to traverse from the beginning and end and assigns the values from the input array to the output array.

	public class Program
	{
	static void Main(string[] args)
	{
	string str = "";
	string reverseString = "";
	Console.WriteLine("Enter a Word");
	str = Console.ReadLine();
	reverseString = stringReverseWithTwoArray(str);
	Console.WriteLine(reverseString);
	Console.ReadLine();
	}
	public static string stringReverseWithTwoArray(string str)
	{
	char[] chars = str.ToCharArray();
	char[] result = new char[chars.Length];
	for (int i = 0, j = str.Length - 1; i < str.Length; i++, j--)
	{
	result[i] = chars[j];
	}
	return new string(result);
	}
	}

view raw ReverseStringWithTwoArray.cs hosted with ❤ by GitHub

Output

2nd  Way

Using Swap Array - Here we will use the swapping for the same also if you look at, we are only traversing half of the array.

	public static string stringReverseWithSwapArray(string str)
	{
	char[] chars = str.ToCharArray();
	for (int i = 0, j = str.Length - 1; i < j; i++, j--)
	{
	char c = chars[i];
	chars[i] = chars[j];
	chars[j] = c;
	}
	return new string(chars);
	}

view raw stringReverseWithSwapArray.cs hosted with ❤ by GitHub

3rd  Way

Using Swap Array - Here we will use any temp variable, so this is for you, here we are using an in-pace swap.

	public static string stringReverseWithTemp(string str)
	{
	char[] chars = str.ToCharArray();
	for (int i = 0, j = str.Length - 1; i < j; i++, j--)
	{
	chars[i] = str[j];
	chars[j] = str[i];
	}
	return new string(chars);
	}

view raw stringReverseWithTemp.cs hosted with ❤ by GitHub

4th  Way

Using Swap Array - Here we will use without copy to char array.

	///String Reversal without Copy to Char Array it's i <= j as we need to getthe middle /// character in case of odd number of characters in the string
	public static string stringReverseWithCopyToChar(string str)
	{
	char[] chars = new char[str.Length];
	for (int i = 0, j = str.Length - 1; i <= j; i++, j--)
	{
	chars[i] = str[j];
	chars[j] = str[i];
	}
	return new string(chars);
	}

view raw stringReverseWithCopyToChar.cs hosted with ❤ by GitHub

Summary

In this tutorial we discussed  how to Reverse a string in C#. If have any question related to this topic then give your feedback.