Software design

Question

1.The algorithm for reading numbers from a file and sorting them in descending order requires considering special cases in my code. I was asked to provide the appropriate internal documentation for this algorithm so the comments make it easy to see the different steps involved and how they are handled. Write the accompanying external documentation to explain this algorithm.

2. What are the four steps in system testing process, and what are the purposes and roles of each one in system testing?

Thanks.