Structured Programming (AQA GCSE Computer Science): Revision Note
Exam code: 8525
Structured Programming
What is structured programming?
Structured programming is the process of breaking down a large problem into a set of smaller problems
The smaller sub-problems are then used to:-
Work out the parameters needed
Decide which data type would be the most appropriate
Work if out if a value is needed to be returned
An examples of this process in computing is:
Computer games
Modern computer games are decomposed to break down the complexity of the problem into more manageable 'chunks'
Creating an entire game at once would be challenging and inefficient, so it could be decomposed into:
Levels - Levels can be designed/created/tested/ independently of other levels
Characters - The mechanics of characters in the game can be designed and created by a separate team
Landscape - The art team can work on the visual aspects of the game without needing to understand how the game is programmed
Once all of the smaller problems are completed, joined together a complex game has been created
Advantages of structured programming
Advantage | Explanation |
|---|---|
Easier to read and understand | Code is organised into small, manageable modules or functions, improving clarity |
Easier to test and debug | Each module can be tested independently, making it simpler to find and fix errors |
Promotes code reuse | Functions or procedures can be reused in different parts of the program or in other programs |
Improves collaboration | Multiple programmers can work on different modules simultaneously without conflicts |
Easier to maintain and update | Changes can be made to individual modules without affecting the whole program |
Reduces complexity | Breaking down large problems into smaller subproblems makes them easier to solve |
Encourages good programming habits | Reinforces the use of clear structures like sequence, selection, and iteration, which are core programming constructs in the AQA spec |
Using a Hierarchy Chart
Problems can be decomposed using tables and lists, however larger problems can quickly become cumbersome using this approach so diagrams are preferred
What is a Hierarchy chart?
A hierarchy chart is an example of a diagram used to show problem decomposition in structured programming
Each problem is divided into multiple subproblems, which is turn are divided into further subproblems until they cannot be divided any further
Hierarchy charts show how module and subroutines relate to each other and is depicted as a tree structure
Hierarchy charts can be created on paper or digitally and can also be created programmatically by software
An example of a hierarchy chart is shown below for a sending messages and calls on a mobile phone. Each sub-problem is broken down into smaller sub-problems:
Worked Example
Mabel is a software engineer. She is writing a computer game for a client. In the game the main character has to avoid their enemies. This becomes more difficult as the levels of the game increase.
The computer game allows a user to select a character (e.g. name, gender). They can then choose a level for the game (easy, normal, challenging). The user controls their character by moving it left or right. The character can jump using space bar as an input. If the character touches one of the enemies then it loses a life. The character has to make it to the end of the level without losing all their lives.
The game is designed in a modular way.
One sub-procedure will handle the user input.
Describe three other sub-procedures Mabel could create for the given game description. [6]
ANSWER
Mabel could create a sub-procedure to select a character, including name and gender, etc [1], which gives the user options when choosing a character [1]
Mabel could create a sub-procedure to choose a level [1] which gives the user a choice of difficulty (easy, medium, challenging) by taking the user input [1]
Mabel could create a sub-procedure to allow the character to lose lives [1]. If the character has less than 0 lives left then the game ends [1]
Examiner Tips and Tricks
Basic input procedures such as moving left and right are not credit worthy but showing the output of a left/right move would be
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