4.1.1.2 Programming concepts

Question 1

What is a keyword?

Answer 1

A word in a programming language that is already defined and can’t be used as an identifier name, e.g print

Question 2

What is a statement?

Answer 2

A single step within the algorithm

Question 3

What is iteration?

Answer 3

A section of code executed repeatedly for a given number of times or until a construct is met. It is a basic construct of procedural programming which helps save memory.

Question 4

What is recursion?

Answer 4

When a function calls itself until it reaches a stopping condition, dividing the program into smaller problems.

Question 5

Advantages of using iteration instead of recursion

Answer 5

Uses only one set of variables, so it uses less space and is more efficient

Question 6

Disadvantages of using iteration over recursion

Answer 6

The algorithm is more difficult to follow due to reusing the same variables. You have to ensure the conditions of the loop are right.

Question 7

What is selection?

Answer 7

A condition that determines whether a section of code will be executed, a basic construct of procedural programming languages

Question 8

What is nesting?

Answer 8

When a construct is written and completely contained within another construct, e.g a nested loop.

Question 9

What is an identifier, why are they used?

Answer 9

A symbolic name given to a subroutine / variable which is clear and meaningful.
Required for the program to store values that can change, make the program easier to understand

Question 10

What are the three combining principles of imperative programming languages?

Answer 10

Sequence, iteration (loops), selection (if)

Question 11

What is the difference between definite and indefinite iteration?

Answer 11

Definite iteration - e.g for loops, the loop iterates for a specified number of times
Indefinite - e.g white loops, the loop runs until the condition has been met

Question 12

What features can make high level language programs easier to understand?

Answer 12

Use of indentation to separate out statement blocks;
Use of comments to annotate the program code;
Use of procedures / functions / sub-routines;
Use of constants
use of meaningful identifier names

Question 13

What are parameters used for in the context of procedures and functions

Answer 13

To pass data/value within programs / to pass data/value in and out of procedures/functions;