Question

I am writing a basic hangman game. I want to store a string Word as the word to be found by the user. My problem is that I want to display this word as underscores (like you do in a paper hangman) but keep it’s string value. A friend of mine said this could be done via Regex but researching it doesn’t seem to help me.

Answer 1

As suggested by Farinha, but using HashSet

Some importang points: we are using a HashSet because in the end the letters can have two states: discovered (present in the HS) or not discovered (not present). We initialize the HashSet passing as a parameter StringComparer.InvariantCultureIgnoreCase because we consider L and l to be the same thing. To use the StringComparer.InvariantCultureIgnoreCase we have to use an HashSet<string> (an HS of strings) instead of an HashSet<char> (an HS of chars). So when using the discovered.Contains() we have to convert the c char in a string with a ToString

static string ConvertWord(string word, HashSet<string> discovered)
{
    StringBuilder sb = new StringBuilder(word.Length);

    foreach (char c in word)
    {
        if (discovered.Contains(c.ToString()))
        {
            sb.Append(c);
        }
        else
        {
            sb.Append('_');
        }
    }

    return sb.ToString();
}

HashSet<string> discovered = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);

// The "secret" word
string word = "Hello world";

// How to add letters to the ones discovered
discovered.Add("l");

// The word ready to be shown
string convertWord = ConvertWord(word, discovered);

We could have done the ConvertWord in much less characters, but for today it’s enough 🙂

Ok… I’ll give you an example, in C# 4.0:

static string ConvertWord(string word, HashSet<string> discovered)
{
    return string.Concat(word.Select(p => discovered.Contains(p.ToString()) ? p : '_'));
}