You've now seen C# in action! We've built a command-line driven version of the SRS application; although this isn't typically how most applications are invoked—most "industrial-strength" applications have GUI front-ends—developing such a version is a crucial step in testing your "core" classes to ensure that all methods are working properly. And, aside from the various Display methods that we encoded for testing purposes, all of the code that we've written for the command-line version of the application will carry forward intact when we round the application out in the next two chapters.