Write a C# Program to Remove Duplicate Characters From String

Write a C# Program to Remove Duplicate Characters From String?

Remove Duplicate characters from String in C# ?

Here, we will discuss how to remove duplicate characters from string.

The string may have two or more same characters in it but we want it to have only one. So let’s look at an example to understand it better.

Required input and output:

Input: Csharpstar
Output: Csharpt

Input: Google
Output: Gogle

Input: Yahoo
Output: Yaho

Input: CNN
Output: CN

Simple way of Implementation:

The essential logic in removing duplicate characters is to check all the chars that have been encountered and avoid adding further characters that have been encountered already.

class Program
    {
        static void Main()
        {
            string value1 = RemoveDuplicateChars("Csharpstar");
            string value2 = RemoveDuplicateChars("Google");
            string value3 = RemoveDuplicateChars("Yahoo");
            string value4 = RemoveDuplicateChars("CNN");
            string value5 = RemoveDuplicateChars("Line1\nLine2\nLine3");

            Console.WriteLine(value1);
            Console.WriteLine(value2);
            Console.WriteLine(value3);
            Console.WriteLine(value4);
            Console.WriteLine(value5);
        }

        static string RemoveDuplicateChars(string key)
        {
            // --- Removes duplicate chars using string concats. ---
            // Store encountered letters in this string.
            string table = "";

            // Store the result in this string.
            string result = "";

            // Loop over each character.
            foreach (char value in key)
            {
                // See if character is in the table.
                if (table.IndexOf(value) == -1)
                {
                    // Append to the table and the result.
                    table += value;
                    result += value;
                }
            }
            return result;
        }
    }

Output:

Csharpt
Gogle
Yaho
CN
Line1
23.