How can you remove duplicate characters in a string?

Question

I have to implements a function that takes a string as an input and finds the non-duplicate character from this string.

So an an example is if I pass string str = \"

Answer 1

It will do the job

string removedupes(string s)
{
    string newString = string.Empty;
    List<char> found = new List<char>();
    foreach(char c in s)
    {
       if(found.Contains(c))
          continue;

       newString+=c.ToString();
       found.Add(c);
    }
    return newString;
}

I should note this is criminally inefficient.

I think I was delirious on first revision.

Answer 2

// Remove both upper-lower duplicates

public static string RemoveDuplicates(string key)
    {
        string Result = string.Empty;
        foreach (char a in key)
        {
            if (Result.Contains(a.ToString().ToUpper()) || Result.Contains(a.ToString().ToLower()))
                continue;
            Result += a.ToString();
        }
        return Result;
    }

Answer 3

    void removeDuplicate()
    {
      string value1 = RemoveDuplicateChars("Devarajan");
    }

     static string RemoveDuplicateChars(string key)
    {
        string result = "";          
        foreach (char value in key)
            if (result.IndexOf(value) == -1)                   
                result += value;
        return result;
    }

Answer 4

char *remove_duplicates(char *str) { char *str1, *str2;

if(!str)
    return str;

str1 = str2 = str;

while(*str2)            
{   
    if(strchr(str, *str2)<str2)
    {
        str2++;
        continue;
    }

    *str1++ = *str2++;      
}
*str1 = '\0';

return  str;

}

Answer 5

Not sure how optimal it is:

public static string RemoveDuplicates(string input)
{
    var output = string.Join("", input.ToHashSet());
    return output;
}

Answer 6

var input1 = Console.ReadLine().ToLower().ToCharArray();
var input2 = input1;
var WithoutDuplicate = input1.Union(input2);