Software life cycle

The major steps in making a program are:

· Requirements. Programs start when someone gets an idea and starts to implement it. The requirement document describes, in very general terms, what is wanted.

· Program specification. The specification is a description of what theprogram does. In the beginning, a preliminary specification is used to describe what the program is going to do. Later, as the program becomes more refined, so does the specification. Finally, when the program is finished, the specification serves as a complete description of what the program does.

· Code design. The programmer does an overall design of the program. The design should include major algorithms, module definitions, file formats, and data structures.

· Coding. The next step is writing the program. This step involves first writing a prototype and then filling it in to create the full program.

· Testing. The programmer should design a test plan and then use it to test his program. When possible, the programmer should have someone else test the program.

· Debugging. Unfortunately, very few programs work the first time. They must be corrected and tested again.

· Release. The program is packaged, documented, and sent out into the world to be used.

· Maintenance. Programs are never perfect. Bugs will be found and will need correction. This step is the maintenance phase of programming.

· Revision and updating. After a program has been working for a while, the users will want changes, such as more features or more intelligent algorithms. At this point, a new specification is created and the process starts again.

Source: Practical C Programming, Third Edition -O'Reilly Media