CSHARP

c sharp type in word and calculate how much a letter is inside that word

public static int countLetters(string word, string countableLetter)
{
    int count = 0;
    foreach (char c in word)
    {
        count++;
    }
    return count;
}

c sharp type in word and calculate how much a letter is inside that word

public static int countLetters(string word, string countableLetters)
{
    int count = 0;
    foreach (char c in word)
    {
        if(countableLetters.Contains(c))
           count++;
    }
    return count;
}