2.2.6. Programming Techniques

Question 1

Sequence

Answer 1

the code is executed line by line, from top to bottom (sequentially)

Question 2

Branching/ selection

Answer 2

BRA - always branch
BRP - branch if the value is positive (or zero)
BRZ - branch if the value is zero
A certain block of code is run if a specific condition is met, using IF statements

Question 3

Iteration

Answer 3

A block of code is executed a certain number of times (FOR loop) or until a condition is met (WHILE loop)

Question 4

What is Recursion

Answer 4

• Where a subroutine calls itself within its own subroutine until a (stopping) condition is met.

Question 5

Advantage of Recursion

Answer 5

The code is represented in fewer lines of code

Question 6

Disadvantages of Recursion

Answer 6

• inefficient use of memory. If the subroutine calls itself too many times, there is a risk of stack overflow which will cause the program to crash
• errors within recursion are difficult to trace

Question 7

Global Variables

Answer 7

Can be accessed across the whole program

Question 8

Global variable disadvantages

Answer 8

• can be unintentionally overwritten

- requires more memory as they aren’t deleted once the subroutine is completed.

Question 9

Local variables

Answer 9

local variables have a limited scope which means that they can only be accessed within the subroutine in which they were defined in

Question 10

Local variable advantages

Answer 10

• ensures subroutines are self-contained (good practice in coding)
• multiple local variables with the same name can exist in different subroutines (won’t overwrite each other)

Question 11

Modularity (top-down programming)

Answer 11

Splitting large, complex problems into smaller self-contained modules
- makes it easier to divide tasks between a team as each component is self contained

Question 12

Procedure and function similarity

Answer 12

Procedures and functions are both named blocks of code that perform a specific task

Question 13

Procedure vs function

Answer 13

Procedures don’t have to return a value whereas a function must always return a value

Question 14

IDEs

Answer 14

• A program which provides a set of tools to make it easier to write, develop and debug code
• Debugging tools have run-time detection of errors to show where they may have occurred
• Stepping which allows you to monitor the effect of each individual line of code by executing line by line
• Source code editor which provides features such as autocompletion of words, indentation, syntax highlighting and automatic brack completion

Question 15

Class

Answer 15

A class is a template for an object and defines the state and behaviour of an object
It is not an object itself. It is a template used to set or define what attributes and methods an object has.
Once you have defined a class, you can easily reuse that class and create many objects of that class.

Question 16

Inheritance

Answer 16

subclasses inherit methods and attributes from the superclass. Using inheritance, you can reuse the code from a class and extend its attributes and methods.

Question 17

Encapsulation

Answer 17

When attributes are made private.
Public methods are needed to read/ amend the attribute’s value
- used to hide values or the internal state of an object preventing direct access by unauthorised third parties
- reduces human error

Question 18

Object Orientated Techniques

Answer 18

Attempts to capture or group info and data and related functionality (code) into structured items known as objects.