How To Replace Characters In A C# String

Introduction

The String.Replace() method replaces a character or a string with another character or string in a string.

In C#, Strings are immutable. That means the method does not replace characters or strings from a string. The method creates and returns a new string with new characters or strings.

String.Replace() method has two overloaded forms.

Method	Description
Replace(Char, Char)	Returns a new string in which all occurrences of a specified Unicode character in this instance are replaced with another specified Unicode character.
Replace(String, String)	Returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.

Example 1

The following example replaces all commas with a colon in a string.

// Replace a char  
string odd = "1, 3, 5, 7, 9, 11, 13, 15, 17, 19";  
Console.WriteLine($"Original odd: {odd}");  
string newOdd = odd.Replace(',', ':');  
Console.WriteLine($"New Odd: {newOdd}");  

The following example replaces all “ Beniwal” with an empty string so only first names are copied to the new string.

string authors = "Mahesh Beniwal, Neel Beniwal, Raj Beniwal, Dinesh Beniwal";  
Console.WriteLine($"Authors with last names: {authors}");  
// Remove all Beniwal with space and remove space with empty string  
string firstNames = authors.Replace(" Beniwal", "");  
Console.WriteLine($"Authors without last names: {firstNames}");  

The complete program is listed in Listing 1. 

using System;  
namespace ReplaceStringSample {  
    class Program {  
        static void Main(string[] args) {  
            /** Replace sample **/  
            // Replace a char    
            string odd = "1, 3, 5, 7, 9, 11, 13, 15, 17, 19";  
            Console.WriteLine($ "Original odd: {odd}");  
            string newOdd = odd.Replace(',', ':');  
            Console.WriteLine($ "New Odd: {newOdd}");  
            string authors = "Mahesh Beniwal, Neel Beniwal, Raj Beniwal, Dinesh Beniwal";  
            Console.WriteLine($ "Authors with last names: {authors}");  
            // Remove all Beniwal with space and remove space with empty string    
            string firstNames = authors.Replace(" Beniwal", "");  
            Console.WriteLine($ "Authors without last names: {firstNames}");  
            Console.ReadKey();  
        }  
    }  
}  

Listing 1.

The output of Listing 1 looks like Figure 1.

Figure 1.

Here is a detailed tutorial: Strings in C#