keszi

File file = SD.open("user.dat");
if (file) {
    string user;
    string password;
    while (string line = file.ReadLine()) {
        foreach (line as s) {
            while (s != "@") {
                user += s;
            }
        }
        if (user == __USER_INPUT_VARIABLE__) {
            int i = 0;
            for (; i<=line.length(); i++) {
                if (line[i] == "@") {
                    break;
                }
            }
            for (; i<=line.length(); i++) {
                password += line[i];
            }
            break;
        }
    }
    file.close();

    if (password == __USER_INPUT_VARIABLE__) {
        doLoginProc();
    }
}