string::size_type find_char(const string &s, const char c,
    string::size_type &occurs) {
    occurs = 0;
    auto ret = s.size();
    for (decltype(s.size()) i = 0; i != s.size(); ++i) {
        if (s[i] == c) {
            if (ret == s.size()) {
                ret = i;
            }
            ++occurs;
            cout << "occurs=" << occurs << endl;
        }
    }
    return ret;
}
int main() {
    string s = "jixiansheng";
    string::size_type occ = 0;
    cout << "first: " << find_char(s, 'i', occ) + 1
        << "\noccurs: " << occ << endl;
    cout << "occ=" << occ << endl;
    getchar();
    return 0;
}