How to reverse a string in C#

Reverse a string using iterative method

The algorithm to reverse a string in C# is as follows:

  1. Convert the string into an array of characters using the ToCharArray() method.

  2. Reverse the character array using Array.Reverse method.

  3. Create a new string from the reversed array. This will result in reversing the original string.

Example

Let's write the C# program to reverse the string.

using System;
class ReverseString
{
    static void Main(string[] args)
    {
        string str = "Educative";
        char[] stringArray = str.ToCharArray();
        Array.Reverse(stringArray);
        string reversedStr = new string(stringArray);
        Console.Write($"Actual String is : {str} \n");
        Console.Write($"Reversed String is : {reversedStr} ");
    }
}

Explanation

Here's the explanation for the code above.

  • Line 6: We'll create a string variable with the name str and assign it a value Educative.

  • Line 7: We'll use the ToCharArray() method to convert the string to a character array and store it in the variable stringArray.

  • Line 8: We'll use the Array.reverse() method to reverse the stringArray.

  • Line 9: We'll create a new string variable reversedStr from the stringArray. The reversedStr contains the original string in reverse.

Reverse a method using a StringBuilder

StringBuilder is a mutable string in C#. It helps to modify strings. It provide methods to modify, append, insert, and remove characters from a string without creating a new instance every time.

using System;
using System.Text;
class ReverseString
{
    static void Main(string[] args)
    {
        string str = "Educative";
        string reversedStr = Reverse(str);
        Console.WriteLine(reversedStr);
    }
    static string Reverse(string str)
    {
        StringBuilder reversed = new StringBuilder();
        for (int i = str.Length - 1; i >= 0; i--)
        {
            reversed.Append(str[i]);
        }
        return reversed.ToString();
    }
}

Explanation

  • Line 6: We'll create a string variable with the name str and assign it a value Educative.

  • Line 9: We declare a variable reversedStr, this will hold the output from Reverse method with the string str as an argument. This method reverses the string.

  • Line 15: We initialize the instance of StringBuilder.

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