Remove all non-alpha characters from string
<p>Is there a way how to remove all non-alpha characters (i.e. <code>,.?!</code> etc) from <code>std::string</code> while not deleting czech symbols like <code>ščéř</code>? I tried using: </p>

<pre><code>std::string FileHandler::removePunctuation(std::string word) {
    for (std::string::iterator i = word.begin(); i != word.end(); i++) {
        if (!isalpha(word.at(i - word.begin()))) {
            word.erase(i);
            i--;
        }
    }
    return word;    
}
</code></pre>

<p>but it deletes czech characters.</p>

<p>In the best case, I'd like to use <code>toLowerCase</code> for those symbols too.</p>