12.1 Program Development Life Cycle 开发生命周期简答
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Find questions for 9618-AS-12-01Purpose of a life cycle
A program development life cycle divides development into managed stages。Benefits：
- Easier to plan, manage, schedule and estimate cost/resources。
- Clear deliverables are produced at the end of stages。
- Progress and quality can be reviewed systematically。
- Customer requirements and testing are addressed rather than left until coding ends。
Different projects need different models depending on requirement stability、time、budget、team skills/size、risk、client involvement and need for prototypes。
Models
Waterfall
Stages mainly progress in sequence；output from one stage becomes input to the next。Upward/backward arrows mean a later stage reveals a need to revisit earlier work。
Benefits：clear stages/deliverables；planning and documentation；suitable when requirements are stable and well understood。
Drawbacks：working software appears late；changes are slower/costly；less suitable when requirements evolve or early market delivery matters。
Iterative
The solution is developed through repeated cycles；each version is reviewed and refined。Suitable when requirements need clarification and feedback can improve later versions。
RAD
- Rapid development using prototypes/incremental releases。
- Modules may be developed in parallel。
- Close/continuous client involvement and early review。
- Flexible changes and earlier usable output。
Drawbacks：time/cost may be hard to estimate；documentation may be reduced；requires client availability and skilled team；requirements may keep changing。
Choosing a model
Give model + scenario reason：
Use iterative/RAD because the client is unsure of the interface requirements and can review an early working prototype.
Waterfall is less suitable because requirements are likely to change and working software is not produced until late, delaying release.
Main stages
| Stage | Typical activities/deliverables |
|---|---|
| Analysis | Interview/observe client; identify problems, objectives and requirements; produce requirements specification/feasibility information. |
| Design | Algorithms, modules/structure charts, data structures, identifier tables, file/record structures, UI, validation, test plan/data, language/environment choices. |
| Coding | Implement design in a programming language using IDE/compiler and library routines. |
| Testing | Dry runs, walkthroughs and other tests expose faults; results compared with expected results. |
| Maintenance | Modify released software to correct faults, adapt to change or improve it. |
Exam checklist
- Model choice 是否有 matching reason？
- Waterfall arrows 是否解释 output-to-next-stage 与 return-to-earlier-stage？
- Analysis/design/coding/testing/maintenance activities 是否归类准确？
- Design 是否包含 structures、algorithms、UI、testing，而不是写 requirements interview？
- RAD benefits/drawbacks 是否相对 Waterfall 表述？
本页只整理 lifecycle 简答；开发图绘制与代码实施不在本页。
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