Remove Duplicate characters from String in C#

• This Program is used to remove the characters,which are repeated more than once.

  class DuplicateChar  
   {  
     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);  
       Console.ReadLine();  
     }  
     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;  
     }  
   }