Program Structure¶

Program structure refers to how instructions are organised in a computer program.

Good structure makes a program: - easier to read - easier to test - easier to explain - easier to fix

In assessment, structure is evidence of clear thinking.

Sequencing¶

Sequencing means instructions are executed in order, from top to bottom.

The computer: - starts at the first instruction - runs each line one at a time - stops only when told to stop

If instructions are in the wrong order, the program may still run — but behave incorrectly.

Variables are used to store data.

They allow a program to: - remember values - use input later - change behaviour over time

Examples of what variables might store: - a score - a player position - a number entered by the user - the number of lives remaining

Clear variable names improve readability and understanding.

Instructions tell the computer to do something.

Examples include: - calculating a value - displaying output - updating a variable - calling a function

Each instruction should have a clear purpose.

Programs often need to choose between different paths.

This is done using conditions.

A condition checks whether something is: - true or false - equal or not equal - greater or less than

Figure 3 — Program flow with a decision point

flowchart TD
    Start --> Input
    Input --> Processing
    Processing --> Output
    Output --> End

Decisions control how the program responds to different situations.

A program should be readable by: - you - your teacher - someone else learning from your work

Good readability includes: - clear variable names - consistent formatting - logical ordering of instructions

Messy code is harder to verify and harder to assess.

In AS92004, you are assessed on: - whether your program works - whether the logic is correct - whether you can explain how it works

Clear structure helps with all three.

Program structure is reused when: - building game mechanics - handling player input - managing game states - debugging unexpected behaviour

Structure learned here will appear again in game development.

End of Program Structure