6.4 Exercises

1. The source code of a high-level programming language is much more formal than its natural language equivalent. Yet most people, at some time, have developed programs that fail to behave as expected at runtime. Why should this occur? How can diagrams and diagramming help us to produce predictable, reliable programs?
2. Which diagrams would you generate when doing a standalone, single-processor non-tasking design? Explain your reasoning.
3. Until recently, relatively few software projects have used diagramming as a design technique. With this in mind, explain why there is much truth in the following claim: 'during the maintenance phase, approximately 50% of the cost is incurred merely in trying to work out what the existing system is supposed to do.'