C# program to Reverse words in a string

In C#, reversing words in a string means reversing each individual word while keeping the words in their original positions. For example, "Hello World" becomes "olleH dlroW" where each word is reversed but the word order remains the same.

Syntax

Using LINQ with Split(), Select(), and Reverse() methods −

string result = string.Join(" ", str.Split(' ').Select(word => new string(word.Reverse().ToArray())));

Using a traditional loop approach −

string[] words = str.Split(' ');
for (int i = 0; i 

Using LINQ Methods

The most concise approach uses LINQ methods to split the string into words, reverse each word, and join them back together −

using System;
using System.Linq;

class Demo {
   static void Main() {
      // original string
      string str = "Hello World";
      Console.WriteLine("Original: " + str);
      
      // reverse each word using LINQ
      string result = string.Join(" ", str.Split(' ').Select(s => new string(s.Reverse().ToArray())));
      Console.WriteLine("Reversed: " + result);
   }
}


The output of the above code is −

Original: Hello World
Reversed: olleH dlroW


Using Traditional Loop Approach

For better readability and understanding, you can also reverse words using a traditional loop approach −

using System;

class Demo {
   static string ReverseWord(string word) {
      char[] charArray = word.ToCharArray();
      Array.Reverse(charArray);
      return new string(charArray);
   }
   
   static void Main() {
      string str = "Programming in CSharp";
      Console.WriteLine("Original: " + str);
      
      string[] words = str.Split(' ');
      for (int i = 0; i 

The output of the above code is −

Original: Programming in CSharp
Reversed: gnimmargorP ni prahSC


Using StringBuilder for Better Performance

For larger strings or performance-critical applications, using StringBuilder can be more efficient −

using System;
using System.Text;

class Demo {
   static string ReverseWordsWithStringBuilder(string str) {
      string[] words = str.Split(' ');
      StringBuilder result = new StringBuilder();
      
      for (int i = 0; i = 0; j--) {
            reversedWord.Append(words[i][j]);
         }
         
         if (i > 0) result.Append(" ");
         result.Append(reversedWord.ToString());
      }
      
      return result.ToString();
   }
   
   static void Main() {
      string str = "Learn CSharp Programming";
      Console.WriteLine("Original: " + str);
      Console.WriteLine("Reversed: " + ReverseWordsWithStringBuilder(str));
   }
}


The output of the above code is −

Original: Learn CSharp Programming
Reversed: nraeL prahSC gnimmargorP


Comparison

Conclusion

Reversing words in a string in C# can be accomplished using LINQ methods for concise code, traditional loops for clarity, or StringBuilder for performance. The LINQ approach with Split(), Select(), and Reverse() is typically the most elegant solution for most scenarios.