Total words on a sentence..!

int totalWordsOn(string sentence)
    {
        int counter = 0;
        bool wordStarted = false;
        for (int i = 0; i < sentence.size(); ++i)
        {
            int ascii = int(sentence[i]);
            // A - Z = 65 - 90, a - z = 97 - 122
            if ((ascii >= 65 && ascii <= 90) || (ascii >= 97 && ascii <= 122))
            {
                if (wordStarted == false)
                {
                    counter++;
                    wordStarted = true;
                }
            }
            else
            {
                if (wordStarted == true)
                {
                    wordStarted = false;
                }
            }
        }
        return counter;
    }