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How To Remove Duplicate Characters From String In C#

Introduction

In this article, we will examine different methods for eliminating duplicate characters from the specified string in C#.

There are numerous methods to erase duplicate characters from the string, but I will demonstrate three methods for doing so below.

  1. Using LINQ
  2. Using Simple Array
  3. Using HashSet

Below are a few examples of inputs and Outputs.

Example 1

  1. Input: GOOGLE
  2. Result: GOLE

Example 2

  1. Input: MOON
  2. Result: MON

This is an essential technical interview question that may be posed to beginner, intermediate, and experienced candidates.

We previously covered the following.

  1. How to Reverse Number in C#
  2. How to Reverse a String in C#
  3. Palindrome String Program in C#
  4. Palindrome Number in C#
  5. How to Reverse Order of the Given String
  6. How To Reverse Each Word Of Given String

Let’s start.

Using LINQ

Console.WriteLine("Enter a String");
var str = Console.ReadLine();

var strArray = str.ToCharArray()
                  .Distinct()
                  .ToArray();

string result = new string(strArray);
Console.WriteLine($"{result}");

Console.ReadLine();

Output

Output

Using HashSet

We are going to implement the same functionality using HashSet.

Console.WriteLine("Enter a String");
var str = Console.ReadLine();

var strInput = new HashSet<char>(str);
string result = new string(strInput.ToArray());

Console.WriteLine($"{result}");
Console.ReadLine();

Let's execute and see the output.

Output

Execute

Now we will try another simple array method to implement.

Using the Simple Array Method

Console.WriteLine("Enter a String");
var str = Console.ReadLine();
string result = string.Empty;

for (int i = 0; i < str.Length; i++)
{
    if (!result.Contains(str[i]))
    {
        result += str[i];
    }
}

Console.WriteLine($"{result}");
Console.ReadLine();

Output

String Output

We have learned three distinct methods to eliminate duplicate characters from the string. We hope you find this article enjoyable and useful.


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