Paper 2 Programming Techniques

Question 1

What is a variable?

Answer 1

Variables are data values that can change when the user is asked a question, for example, their age. Variables may change during program execution.

Question 2

What is a constant?

Answer 2

Data values that stay the same every time a program is executed are known as constants

Question 3

State the ‘data types’ required for the following variables: student_name

Answer 3

Text / String

Question 4

State the ‘data types’ required for the following variables: student_age

Answer 4

Float i.e. 16.5 years
Integer i.e. 16 years
Date - Date of Birth (can work out a persons age by calculation)

Question 5

State the ‘data types’ required for the following variables: student_sex

Answer 5

Boolean (m/f)

Question 6

State the ‘data types’ required for the following variables: student_height

Answer 6

Float i.e. - 5ft 10 inches

Integer i.e. - 178 cms

Question 7

State the ‘data types’ required for the following variables: student_first_initial

Answer 7

Char (only one letter)

Question 8

Name the 3 constructs of a programming language

Answer 8

• sequence is the order in which instructions occur and are processed.
• selection determines which path a program takes when it is running.
• iteration is the repeated execution of a section of code when a program is running.

Question 9

Explain the difference between how FOR loops and WHILE loops control the flow of instructions during the running of a program.

Answer 9

For loop contains only a single condition whereas while loop may contain a set of commands to be executed together.
In for loop, initialization of command is done only once but in while loop initialization of command is needed each time the iteration of command is done

Question 10

An operator is something which will perform an action on some data. What does an arithmetic operator do?

Answer 10

Arithmetic operators allow arithmetic to be performed on values such as + - / *

Question 11

An operator is something which will perform an action on some data. What does a relational operator do?

Answer 11

Relational operators allow for assignment and enable comparisons to be made. They are used in condition testing such as ==, >, < , <=, >=

Question 12

An operator is something which will perform an action on some data. What does a Boolean operator do?

Answer 12

Logical operators are used to combine relational operators to give more complex decisions such as AND, OR, NOT

Question 13

What is an array (or list in Python)?

Answer 13

An array is a data structure that holds similar, related data. An array is like a collection of boxes, each of which is called an element . Each element has a position in the array, and can hold a value. The data in an array must all be of the same data type .

Question 14

For the given array:
my_array = [“train”, “walk”, “car”, “bus”, “cycle”]
…how would you access the 3rd item?

Answer 14

my_array[2]

Arrays (or lists in Python) always has the first element as 0

Question 15

What is the difference between a 1-dimensional array and a 2-dimensional array?

Answer 15

The main difference between 1D and 2D array is that the 1D array represents multiple data items as a list while 2D array represents multiple data items as a table consisting of rows and columns. … The elements in the array are in subsequent memory locations.

Question 16

Explain the difference between a static and dynamic data structure.

Answer 16

A static data structure is one that has a fixed size and cannot change at run time A dynamic list is able to adapt to accommodate the data inside it and so it does not waste as much space.

Question 17

Why is file handling an important aspect of programming?

Answer 17

Programs process and use data. When the program finishes, or is closed, any data it held is lost. To prevent loss, data can be stored in a file so that it can be accessed again at a later date.

Question 18

What two modes of operations do Files have?

Answer 18

Files have two modes of operation - read from and write to.

Question 19

What is the difference between a ‘Local’ and ‘Global’ variable?

Answer 19

The main difference between Global and local variables is that global variables can be accessed globally in the entire program, whereas local variables can be accessed only within the function or block in which they are defined.

Question 20

What is the difference between a ‘Procedure’ and a ‘Function’?

Answer 20

A function returns a value and a procedure just executes commands.
The name function comes from math. It is used to calculate a value based on input.
A procedure is a set of commands which can be executed in order.