Program Design — common mistakes

Examiners frequently test the difference between structure diagrams and flowcharts. Remember: a structure diagram shows decomposition (what the program is made of). A flowchart shows flow of control (the sequence of steps, decisions, and loops). Your structure diagram should NEVER contain symbols for decisions (diamonds) or loops.

No, they serve different purposes. A structure diagram shows the decomposition of a problem into modules (the 'what'). A flowchart shows the sequence of execution, including steps, decisions, and loops (the 'how'). They are not interchangeable.

For very small, trivial programs, you might get away with it. For any problem of even moderate complexity, coding without a design leads to disorganised, hard-to-read, and difficult-to-debug code. Time spent on design is saved many times over during debugging and maintenance.

They are very closely related. Think of top-down design as the overall strategy: 'Start at the top and break it down'. Stepwise refinement is the process you use to execute that strategy: 'At each step, add more detail until the task is simple enough to code'.

No, you only need to create one if the question explicitly asks for it. However, you should always be thinking in terms of top-down design and modules when you plan your pseudocode answers, as it will lead to better-structured solutions that are easier to write and earn more marks.