Topic 2 Programming

Question 1

Describe a variable.

Answer 1

A named location in the computers memory to store a single value which can change during the execution of a program. Eg radiusOfCircle

Question 2

Describe a constant.

Answer 2

A named location in the computers memory to store a single value which CANNOT change during the execution of a program. Eg the value of Pi.

Question 3

What is an identifier?

Answer 3

The NAME of a variable, constant, procedure or function.

Question 4

What is meant by assignment?

Answer 4

Setting the specific value of a variable. Eg number = 2 means assign the value 2 to the variable called ‘number’.

Question 5

List the arithmetic operators.

Answer 5

+, -, *, /, MOD, DIV, ^

Question 6

Describe the arithmetic operator MOD

Answer 6

Modulus division. Returns the remainder after dividing one number by another. Eg 5 MOD 2 = 1

Question 7

Describe the arithmetic operator DIV

Answer 7

Quotient division. Returns the whole number ignoring any remainder after dividing one number by another. Eg 5 DIV 2 = 2

Question 8

Describe the the arithmetic operator ^

Answer 8

Exponential or power-of. Eg 3^2 = 9 (3 squared)

Question 9

Describe the order or operations in arithmetic operators.

Answer 9

BIDMAS - Brackets, Indices, Division, Multiplication, Addition, Subtraction

Question 10

What are relational operators used for?

Answer 10

To compare different items of data.

Question 11

List/describe the 6 relational operators

Answer 11

= Equal To
<> Not Equal To
< Less Than
> Greater Than
<= Less Then or Equal To
>= Greater Than or Equal To

Question 12

What are logical operators used for?

Answer 12

To combine statements which can be evaluated as TRUE or FALSE.

Question 13

Name the three logical operators.

Answer 13

AND, OR, NOT

Question 14

Describe the AND logical operator

Answer 14

The overall statement is true only if ALL of the individual statements are true.

Question 15

Describe the OR logical operator.

Answer 15

The overall statement is true if ANY of the individual statements are true.

Question 16

Describe the NOT logical operator.

Answer 16

Used to reverse the logical state of other operators.

Question 17

What are the three main programming constructs?

Answer 17

Sequence, Selection & Iteration

Question 18

Describe the sequence construct.

Answer 18

Executing lines of code in the order they are written.

Question 19

Describe the selection construct.

Answer 19

Choosing which lines of code to execute based on a condition being true or false.

Question 20

Describe the iteration construct.

Answer 20

Repeating lines of code either for a set number of times, or while a condition is true.

Question 21

List and describe the five main data types.

Answer 21

Integer - Whole numbers.
Real - Numbers which include fractions/decimals.
Boolean - one of two values - usually True or False.
Character - A single letter, number or symbol.
String - A sequence of characters.

Question 22

What is meant by a ‘string literal’?

Answer 22

Characters enclosed in quotation marks.

Eg name = “Billy” - Billy is the string literal.

Question 23

Describe ‘string concatenation’.

Answer 23

Joining two strings together.
For example:
fname = "Billy"
sname = "Smith"
fullname = fname + sname  (concatenated)

Question 24

Describe an array.

Answer 24

An array is a data structure which can store multiple data items using a single identifier/name. Elements of the array are accessed using an index number which starts from 0.

Question 25

What is a two-dimensional array?

Answer 25

A data structure which uses two index numbers. The array would look like a grid/matrix and elements are accessed using the two indices.
For example array[2,4]

Question 26

What is a sub-procedure or sub-program?

Answer 26

A self contained sequence of program instructions that perform a specific task.

Question 27

Why are sub-programs useful?

Answer 27

• Help with decomposition of a problem
• Make programs shorter as they can be re-used
• Make code easier to read and test
• Can shorten development time

Question 28

What are the two types of sub-program?

Answer 28

• Functions

- Procedures

Question 29

What is the difference between a function and a procedure?

Answer 29

Functions return at least one value to the main program.

Procedures carry out a specific task without returning a value to the main program.

Question 30

What is a parameter?

Answer 30

A value or piece of data passed into a function or procedure (sub-program).

Question 31

What is validation?

Answer 31

Program code which checks that the data input is sensible, reasonable and appropriate.
For example:
In a program where the user was expected to enter a number between 1 and 10, validation would check:
a. A number was entered
b. That number lies between 1 and 10

Question 32

Why is validation important?

Answer 32

Ensures that:

• number of user errors are minimised
• program behaves as expected in spite of user actions