The user interface was to be written in either C or C++ to allow command-line arguments. Thus, this subsystem is very easy to design. It has two major features: interfacing with the operating system to obtain the command-line arguments and determining which arguments are to be passed on to the next subsystem. (The reader unfamiliar with the usage of command-line arguments should read Appendix B.) We note that the system’s software requirements did not specify the development of a GUI for the project. Therefore, we did not consider any GUI tools. The incorporation of a GUI into the design is discussed in Section 4.17 and elsewhere in this chapter. The command-line argument interface is so simple that it does not appear to require any special design; at first glance, using the code in Appendix B as a template appears to be sufficient for our purposes.