char curr = -1, prev = -1;
    while (true)
    {
        auto it = in.get();
        if (it == istream::traits_type::eof())
            break;

        char prevprev = prev;
        prev = curr;
        curr = (char)it;

        if (prev != need)
            continue;

        cout << i++ << ") '" << prevprev << prev << curr << "'\n";
    }