The program development life cycle Cambridge IGCSE Computer Science revision
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In plain words
Nobody builds a house by laying bricks on the first morning. First you find out what is wanted, then you draw plans, then you build, and then you check everything works. Programs are developed in the same four stages.
7 things to know
- Analysis: identify the problem and what the program is required to do. This uses abstraction and decomposition.
- Design: plan the solution, using structure diagrams, flowcharts and pseudocode.
- Coding: write the program code, testing each part as it is written and correcting it (iterative testing).
- Testing: test the finished program with test data.
- Abstraction means keeping the key elements of a problem and leaving out detail that is not needed. Decomposition means breaking a problem down into smaller parts.
- Every computer system is made up of sub-systems, which are made up of further sub-systems. A problem can be decomposed into its inputs, processes, outputs and storage.
- A structure diagram shows this as a hierarchy: the whole system at the top, its sub-systems on the level below, and each of those broken down further.
Worked example
A program is needed to work out the cost of a taxi ride from the distance travelled. Decompose the problem into its component parts.
- Input: the distance travelled.
- Process: multiply the distance by the price for each kilometre, and add the fixed charge.
- Output: the cost of the ride.
- Storage: the price for each kilometre and the fixed charge, which are kept so they can be used every time.
Tips and tricks
- The four stages in order are analysis, design, coding, testing. Know one thing that happens in each.
- Decomposition appears in both analysis and design: the problem is broken down first, then the solution.
It lands in your notebook with its questions as flashcards.
The program development life cycle: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What is the first stage of the program development life cycle?
You have to understand the problem before planning a solution.
In which stage are flowcharts and structure diagrams produced?
Design is where the solution is planned.
What is decomposition?
Each smaller part is easier to solve.
What is abstraction?
A map is an abstraction: it shows roads, not every tree.
What is iterative testing?
It happens during the coding stage.
What does a structure diagram show?
The whole system is at the top, with each level below in more detail.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 10 marks. Write your answers on paper, then check them.
The program development life cycle
Cambridge IGCSE Computer Science 0478 · 10 marks · papermunch.org
Name ______________________________ Date ______________
State the four stages of the program development life cycle, in order.[4]
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Analysis, design, coding and testing.
Describe what is meant by abstraction.[2]
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Keeping the key elements of a problem and removing detail that is not needed to solve it.
A program checks whether a library book is overdue. Identify one input, one process, one output and one item of storage.[4]
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Input: the book's number. Process: compare the date it was due back with today's date. Output: a message saying whether it is overdue. Storage: the date each book is due back.
Answers: The program development life cycle
- 1. Analysis, design, coding and testing.
- 2. Keeping the key elements of a problem and removing detail that is not needed to solve it.
- 3. Input: the book's number. Process: compare the date it was due back with today's date. Output: a message saying whether it is overdue. Storage: the date each book is due back.