C# Can I use FileStream for StreamReader(fs) and StreamWriter(fs, append: true) at the same time?

Question

So basically i was struggling with hangman and i couldn't figure out how to solve it the first problem. That's why i thought i might put in another function; a method to add a word to my textfile of words with StreamWriter using FileStream. (I have a StreamReader too, so i can see what random word it would choose.)

Things tried (with all: writer.WriteLine(text)):

1. I tried using StreamWriter writer = new StreamReader(fs.ToString(), append: true) with FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None)

2. I tried FileMode.Append (because i want to append), but that only works in write-only mode and i need to read text too.

3. I tried to use the filestream without the ToSting(), but that resulted in "Cannot convert from 'System.IO.FileStream' to 'string'."

4. I tried to do the same thing in a different program but only with StreamReader and FileStream, but it still didn't change anything in the textfile.

What I actually wish it would do: I expect that the program will be able to append a string to the textfile while still being able to read the chosen word. (When you start the program a random word out of the textfile is chosen.)

Sorry if this looks messy, it's my first time asking a question on stackoverflow.

So why this is different from the duplicate is because i want to append the file, not write (overwrite) it. I tried the exact same FileStream as the "duplicate", but it only got rid of the error. Now I'm still stuck with a malfunctioning StreamWriter.

Part of the code:

    private static FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
    private static StreamReader reader = new StreamReader(fs);

    private static string[] words = reader.ReadToEnd().Split(',');

    public static Random randomizer = new Random();
    private static int wordindex = randomizer.Next(0, words.Length);


    public string GetWord()
    {
        return words[wordindex]; //returns random value out of array = random woord
    }

`

And using for StreamWriter:

public string AddWordToFile(string word)
    {
        using (StreamWriter writer = new StreamWriter(fs.ToString(), append: true))
        {
           //bool ExistsInFile = false;
            for (int i = 0; i < words.Length; i++)
            {
                if (words.Contains(word))
                {
                    //ExistsInFile = true;
                    return "The word '" + word + "' already exists in the textfile.";
                }
            }
            if (!words.Contains(word))
            {
                //ExistsInFile = false;
                writer.WriteLine("," + word);
                writer.Close();
                return word + " added.";
            }
            else
            {
                return "Whoops, something went wrong :'I";
            }
        }              
    }      

Answer 1

Another way to do it would be this:

    static void ReadAndWrite()
    {
        string file = File.ReadAllText(@"C:\whatever.txt"); //read C:\whatever.txt
        File.AppendAllText(@"C:\whatever.txt", "Text to append"); //append "Text to append" to C:\whatever.txt
    }

I've tested this and it works just fine on my PC.

Maybe it helps you.

Edit: This is much easier and reads every line in a file into a string array:

    static void ReadAndWrite()
    {
        string[] words = File.ReadAllLines(@"C:\whatever.txt");
        File.AppendAllText(@"C:\whatever.txt", "Word to append\r\n"); //append "Word to append" in a new Line to C:\whatever.txt
    }

To get an array of words, write every word into a new line by also appending \r\n after every word like in the example. This way, you get an array of every word in your file.