C# Program Remove Special Characters from String.

In C#, multiple ways exist to remove special characters from a given string. This is a significant problem that we often face when we try to compare two different strings. In this article, we are going to discuss three different ways to remove special characters from a given string.

Approach 1: Using Regular Expressions.

You can utilize regular expressions (Regex) to remove special characters from a string in C#. This method is flexible and allows you to specify which characters to keep or remove.

Example Code: 

// C# program to remove special character using regular expression

using System;
using System.Text.RegularExpressions;

public class HelloWorld
{
    static string RemoveSpecialCharactersRegex(string input)
    {
        // Regular expression pattern to match special characters
        string pattern = @"[^a-zA-Z0-9\s]";
        
        // Regex.Replace to remove special characters from the input string
        return Regex.Replace(input, pattern, "");
    }
    
    public static void Main(string[] args)
    {
        string inputString = "Hello, @World! 123";
        
        // Remove special characters from the input string using Regex
        string result = RemoveSpecialCharactersRegex(inputString);
        
        Console.WriteLine("Original String: " + inputString);
        Console.WriteLine("String with Special Characters Removed: " + result);
    }
}

Output:

Original String: Hello, @World! 123
String with Special Characters Removed: Hello World 123

Approach 2: Using LINQ and Char.IsLetterOrDigit.

You can use LINQ to filter out characters that are letters or digits, effectively removing special characters. This approach will also remove spaces between two words if exist.

Example Code: 

// C# code to remove speical characters from string using LINQ

using System;
using System.Linq;

public class Program
{
    static string RemoveSpecialCharactersLinq(string input)
    {
        // Use LINQ to filter out non-alphanumeric characters and spaces
        string cleanedString = new string(input.Where(char.IsLetterOrDigit).ToArray());
        return cleanedString;
    }

    static void Main(string[] args)
    {
        string inputString = "Hello, @World! 123";
        
        // Remove special characters from the input string using LINQ
        string result = RemoveSpecialCharactersLinq(inputString);
        
        Console.WriteLine("Original String: " + inputString);
        Console.WriteLine("String with Special Characters Removed: " + result);
    }
}

Output:

Original String: Hello, @World! 123
String with Special Characters Removed: HelloWorld123

Approach 3: Using a String Builder.

Using a StringBuilder is a memory-efficient approach for removing special characters from a string. The key advantage of this approach is that it minimizes memory overhead compared to creating multiple string objects. 

Example Code:

// C# code to remove special character using stringbuider function
using System;
using System.Text;

public class Program
{
    static string RemoveSpecialCharactersStringBuilder(string input)
    {
        StringBuilder sb = new StringBuilder();
        
        foreach (char c in input)
        {
            if (char.IsLetterOrDigit(c) || char.IsWhiteSpace(c))
            {
                sb.Append(c);
            }
        }
        
        return sb.ToString();
    }

    static void Main(string[] args)
    {
        string inputString = "Hello, @World! 123";
        
        // Remove special characters from the input string using a StringBuilder
        string result = RemoveSpecialCharactersStringBuilder(inputString);
        
        Console.WriteLine("Original String: " + inputString);
        Console.WriteLine("String with Special Characters Removed: " + result);
    }
}

Output:

Original String: Hello, @World! 123
String with Special Characters Removed: Hello World 123

All three approaches will remove special characters and return a string containing only alphanumeric characters and spaces. You can choose the method that best fits your requirements and coding style.