Programming

Question 1

What is a procedure?

Answer 1

A subroutine that does not return a value

Question 2

What is a function?

Answer 2

A subroutine that return a value

Question 3

How can you tell if a variable is a constant?

Answer 3

Named with all capital letters e.g. EMPTYSTRING

Question 4

What is a local and global variable?

Answer 4

• A local variable is declared in a subroutine or similar
• A global variable is declared at the highest possible level in a program so that it can be used in any lower level statements

Question 5

What are programming paradigms?

Answer 5

Approaches to programming

Question 6

What are the two main paradigms in programming?

Answer 6

1) Functional programming
2) Imperative programming

Question 7

What are the two main types of imperative programming?

Answer 7

1) Procedural programming
2) Object-Oriented programming

Question 8

What is functional programming?

Answer 8

Programming that has no variables, and instead uses functions as mappings from one value to another

Question 9

What is imperative programming?

Answer 9

Programming that has commands that the computer performs in a specific sequence

Question 10

What is procedural programming?

Answer 10

• Programming made up of imperative commands that are run sequentially
• Uses sequence, selection and iteration
• Broken up into smaller parts or modules using subroutines

Question 11

What are the main parts of the structured approach to programming?

Answer 11

1) Organise programs into subroutines and modules by using hierarchy charts to break a program down

2) Store data in variables and constants with meaningful identifiers

3) Program to the interface by using subroutines

4) Use local variables instead of global variables

5) Use indentation, spacing and comments

Question 12

What are the advantages to using the structured approach to programming?

Answer 12

• Can individually test subroutines and modules
• Modules with related subroutines make it easy to navigate for developers
• Indented code is easier to read
• Comments can explain how program works to other developers
• Meaningful identifiers make it easier to follow
• Parameters and return values to pass values into and out of subroutines reduces likelihood for errors

Question 13

Why is it good practice to use local variables?

Answer 13

• Modularisation of a program
• Allows re-use of subroutines
• Less chance of side effects

Question 14

What is the difference between a local and global variable?

Answer 14

Local variables have a more limited scope.
Global variables can be accessed from any part of the program.

MS:
Mark is for AO1 (understanding)
Local variables have more limited scope;
Global variables exist throughout the entire program;
Local variables only exist in a part/block/subroutine of the program;
Local variables can only be accessed in a part/block/subroutine of the program;
Global variables can be accessed from any part of the program;
Max 1 mark

Question 15

What is the difference between a protected and a private attribute?

Answer 15

Question 16

Why is it good practice to use local variables?

Answer 16

Mark is for AO1 (knowledge)

Modularisation of a program;
Allows reuse of subroutines;
Less chance of side-effects;

Max 1 mark

Question 17

What is meant by the base case of a recursive subroutine?

Answer 17

The circumstance(s) when a recursive subroutine does not call itself;

Question 18

What are the components of the stack frame?

Answer 18

local variables;
return address;
parameters;
register values;

Question 19

State advantages of using subroutines.

Answer 19

Easier to test/debug as each subroutine can be tested separately;
Easier to understand the code if sensible identifiers are used for subroutine names;
Code can be easily reused as each subroutine is independent of rest of program;
Makes it easier to work as a team of programmers as each subroutine can be
worked on independently;
Can be used as often as needed without having to write the code each time;
Makes program easier to maintain/update (in future) as fewer changes will need to
be made to make an update;
Allows the use of recursive techniques because subroutines can call themselves;
Easier to understand the code as each subroutine can be considered in isolation;
Less likely to be errors in the code due to reuse of code;
Reduces/eliminates side effects (eg unexpected change to value in global variable)
through use of local variables;

Question 20

What is string concatenation?

Answer 20

Joining (two) strings (to form one string // into one);

Question 21

What is encapsulation?

Answer 21

Combining a record with the procedures and functions that manipulate it in order to create a new data type;

Question 22

What is polymorphism?

Answer 22

Objects of different classes / types respond differently to the use of a common interface / the same usage

Question 23

What is method overriding?

Answer 23

When a derived class / subclass has a different implementation for a method /
function / subroutine to the class it inherits from / from the base class;

Question 24

What are the differences between virtual and abstract methods?

Answer 24

Virtual methods can be overridden by the derived class //
virtual methods do not have to be overridden //
abstract methods must be overridden by the derived class;
Virtual methods have an implementation/body //
virtual methods contain code (with functionality) (in the base class) //
abstract methods do not contain an implementation/body //
abstract methods contain no code (with functionality) (in the base class) //
abstract methods only contain a declaration (in the base class);
Abstract methods can only be declared in abstract classes //
virtual methods can be declared in abstract and non-abstract classes;

Question 25

When is it suitable to use a private method?

Answer 25

Because it is only called by methods inside the class // because it is never used/called from outside the class;

Question 26

What is the difference between a local variable and a private attribute?

Answer 26

A local variable can only be used in the method/subroutine/program block in which it is declared whereas a private attribute can be used/accessed anywhere in the class;

Question 27

Why favour composition over inheritance?

Answer 27

There can be unintended side effects for derived class by altering a method in the base class.

Question 28

How to get all ASCII letters?

Answer 28

Ascii code between 65 and 90 and uppercase between 97 and 122

Question 29

Explain why setting attributes and using public getter methods to access them is favoured in object-oriented programming.

Answer 29

The way that the attribute is represented can be modified without having to change any other objects that interact with the attribute;