Development Strategy for C Programs

It is important that you develop your code development, debugging and testing skills. We can provide guidance during office hours, but it is important that you have a strategy that helps you develop, test and debug your code on your own and with the minimal assistance possible.

Below we provide information about a strategy you should follow while implementing code. If you are taking cmsc216, and you are looking for help during office hours, we expect you to follow a similar strategy, otherwise we will not be able to help you :(. The strategy can be summarized as follows:

Strategy Summary

Add code incrementally (e.g., code fragment or a function) → If you write a lot of code you are making the debugging task harder. The code you write should have good indentation and good variable names from the start. This will make the debugging task easier and help TAs provide assistance.
Do not ignore compilation warnings.
Create your own tests → Make sure the code you just added is correct by creating your own tests. Usually provided tests (e.g., public tests) test several aspects of your code simultaneously. You need a test that is specific to the code you just wrote. Also, submit your code often to the submit server to verify your code works as expected in the server.
Rely on tools like Valgrind, gdb, splint → Use tools like Valgrind to identify common errors like reading unitialized data, performing invalid read / write operations, or dynamic memory problems. You need to run Valgrind after you add some code and not once you have implemented all your code. Tools like splint can help as well. If you code is generating a seg fault / core dump, use Valgrind or gdb (where option) to identify the problem. If this does not work, step through the code using the simple test you developed.
Backup your code → Once your code is working, create a backup of the code before you continue working. Backups help as sometimes you would like to go back to code you had (or in case you delete your code by mistake).
Take breaks → Many errors can be found easily if you take a break and focus on something else.
Go back to step one.

Additional Information

One of the most important rules when developing code is incremental code development: add a little bit, make sure it works and move forward. How much is a little bit varies. At any point you have to be able to answer the following question: "up to what point my code worked?"
As you write your code, you need to write your own tests. Even if tests are provided, writing your own tests will allow you to thoroughly test your code and identify errors early. If you are looking for help during office hours, you need to have a test that illustrates the problem you are having. This test must be as simple as possible. In our classes we provide tests and expected output, but in the real world you need to write your own tests :). Start practicing now. Often students stop by looking for help with a provided test (public test) and they just indicate "my code is not passing the test". If your code is not passing a provided test, simplify the test to narrow down where the problem is taking place. Once you have narrow down the problem, then we can provide help.
Knowing debugger basics is enough. If you know how to set a breakpoint, step through code and change between frames you are set. If you use incremental code development chances are you may not use the debugger that often (or at all). By the way, if using a print statement helps you find your problems go ahead. However, you should know debugger basics (you want to look cool in that internship/job :)).
Visit Debugging in C Guidelines