How to change goto statement to improve code?

Question

I am writing a C# Windows Form app. I have a label with a random word, e.g. "computer". User sees covered word, in this example: "--------". User has to guess what is this word by guessing letter by letter. I created button Hint. The button is responsible for revealing one random letter. That's code I created:

private void btnHint_Click(object sender, EventArgs e)
{
    repeat:
    Random rnd = new Random(); 
    int rand = rnd.Next(corrArr.Length); 
    char letter = corrArr[rand]; 

    if (letters.Contains(letter.ToString())) //check if the random letter is already used
    {
        goto repeat; 
    }
    else
    {
        word.Text = "";

        var idx = correct.IndexOf(letter);
        wordArr[idx] = Convert.ToChar(letter);

        foreach (var item in wordArr)
        {
            word.Text += item.ToString();
        }
        count++;
        
        if (wordLen == count)
        {
            this.BackColor = Color.LimeGreen; 
            result.Text = "Win!!";
            tb.Enabled = false; 
            btnClick.Visible = false; 
        }
    }
    letters.Add(letter.ToString());
}

By goto statement I can draw a letter again, if the previous one is already used.

I heard that I shouldn't use goto statement like in the beginning of code, but program works perfectly. How can I improve code?

Answer 1

Leave the if/else statement and use Do While loop

tutorialsteacher

Random rnd = new Random(); 
char letter;
do
{
      int rand = rnd.Next(corrArr.Length); 
      letter = corrArr[rand]; 
} while (letters.Contains(letter.ToString()));

 word.Text = "";

 var idx = correct.IndexOf(letter);

 wordArr[idx] = Convert.ToChar(letter);

And of course there is more to be improved... ;)