10.3 Thinking Procedurally

Question 1

Procedural Decomposition

Answer 1

Breaking a problem into a number of sub-problems, so that each sub-problem accomplishes an identifiable task (sub-problems may be divided even more)

Question 2

Structured programming

Answer 2

A method of writing a computer program which uses:
- Modularization for program structure and organisation (breaking the problem down into subroutines)
- Structured code for the individual modules - that is, code which uses the basic constructs of sequence, selection and iteration
- Recursion

Question 3

What are hierarchy charts often used for?

Answer 3

To show overall program structure

Question 4

Hierarchy chart

Answer 4

• Each logical process is broken down into smaller components until it cannot be broken down any further
• Execution takes place from left to right, always at the lowest level component
• Selection and iteration are not shown in a hierarchy chart

Question 5

Modularisation further advantages

Answer 5

• Large programs are broken down into subtasks/subroutine that are easier to program and manage
• Each subroutine can be individually tested
• Modules can be re-used several time in a program
• Frequently used modules can be saved in a library and used by other programs
• Several programmers can simultaneously work on different modules, shortening development time
• Easier to find errors in small self contained modules
• Well-organised, modular program is easier to follow
• Easier to find which module needs to be changed
• Self-contained modules mean that the change should not affect the rest of the program
• New features can be added by adding new modules

Question 6

Modularisation advantages

Answer 6

• Programs are more easily and quickly written
• Programs are more reliable and have fewer errors
• Programs take less time to test and debug
• Programs are easier to maintain

Question 7

Good programming practice techniques

Answer 7

• Meaningful indentifiers
• Define and document the inputs, outputs and preconditions for each sub-procedure
• Add lots of meaningful comments within the program
• At the bottom level, each sub-procedure should perform a single task
• Keep each sub-procedure self-contained by passing parameters and using local variables

Question 8

Identifying the components

Answer 8

Involves writing procedures or functions and passing parameters