c++ strip_tags replace_all

strip_tags.cpp

string &replace_all(string &content, const string &from, const string &to)
{
    size_t i = 0;
    size_t j;
    while((j = content.find(from, i)) != string::npos) {
        content.replace(j, from.size(), to);
        i = j + to.size();
    }
    return content;
}
    
string &strip_tags(string &html)
{
    bool inflag = false;
    bool done = false;
    size_t i, j;
    while (!done) {
        if (inflag) {
            i = html.find('>');
            if (i != string::npos) {
                inflag = false;
                html.erase(0, i+1);
            }
            else {
                done = true;
                html.erase();
            }
        }
        else {
            i = html.find('<');
            if (i != string::npos) {
                j = html.find('>');
                if (j == string::npos) {
                    inflag = true;
                    done = true;
                    html.erase(i);
                }
                else {
                    html.erase(i, j-i+1);
                }
            }
            else {
                done = true;
            }
        }
    }

    return html;
}