Working on PSET2 - Readability wherein I have a function set up to count letters. I had this working previously by way of some backwards logic (I had it checking if each char was NOT a space or special char and only counting if true) and decided to redesign it to be more straight-forward. I'm now trying to use isalpha() to check each char, but I'm getting a return of 0 letter(s) every time.

int count_letts(string s)
{
    int x = 0;

    for(int i = 0, n = strlen(s); i < n; i++)
    {
        if(isalpha(s[i]) == true)
        {
            x++;
        }
    }

    return x;
}

I have a function for counting words that's almost identical to this using isblank() that works perfectly fine. I've read the man pages and notes from the lectures a couple times, Googled and searched this subreddit, but I don't see anyone with the same issue. What am I doing wrong?