Section 11 Programming Techniques

Question 1

Programming Constructs

Answer 1

● Sequence
○ Code is executed line-by-line, from top to bottom
● Branching
○ Particular block of code is run if a specific condition is met
○ Uses IF and ELSE statements
● Iteration
○ Can be either:
■ Count-controlled
● Block of code executed a certain number of times
■ Condition-controlled
Block of code is executed while a condition is met
○ Uses FOR, WHILE or REPEAT UNTIL loops

Question 2

Global and Local Variables

Answer 2

Local Variables
● Can only be accessed within the subroutine in which they were defined
● Multiple local variables with the same name can exist in different subroutines
● Are deleted once subroutine ends
● Using local variables ensures subroutines are self-contained
Global Variables
● Can be accessed across the whole program
● Useful for values that need to be used by multiple parts of the program
● Danger of being unintentionally edited
● Not deleted until program terminates, so require more memory

Question 3

Scope

Answer 3

the section of code in which the variable can be accessed

Question 4

A local variable within a subroutine

Answer 4

takes precedence over a global variable
with the same name

Question 5

Modular programming

Answer 5

● Modular programming is a technique used to split large, complex programs
into smaller, self-contained modules
● Easier to divide tasks between a team and manage projects
● Simplifies the process of testing and maintenance, as each component can be
dealt with individually
● Improves reusability of components

Question 6

Top-down Design/ Stepwise Refinement

Answer 6

Technique used to modularise programs
● Problem is broken down into sub-problems, until each is represented as an
individual, self-contained module which performs a certain task
● Modules form blocks of code called subroutines

Question 7

Functions and Procedures

Answer 7

● Both named blocks of code that perform a specific task
● Procedures do not have to return a value
● Functions must always return a single value
● Parameters can be passed into a subroutine either by value or by reference

Question 8

Passing by Value

Answer 8

● A copy of the value is passed to the subroutine and discarded at the end
● Its value outside of the subroutine remains unaffected

Question 9

Passing by Reference

Answer 9

● Address of parameter is given to the subroutine
● Value of the parameter will be updated at the given address

Question 10

In exam questions, you should assume parameters are passed

Answer 10

by value unless you
are told otherwise. The following format will be used:

function multiply(x:byVal, y:byRef)

Question 11

Use of an IDE (Integrated Development Environment)

Answer 11

Program which provides a set of tools to make it easier for programmers to
write, develop and debug code
● Features of IDEs include:
○ Stepping
○ Variable watch
○ Breakpoint
○ Source code editor
○ Debugging tools