C) Programming Paradigms

Question 1

What are some data types?

Answer 1

• Boolean: true or false
• character: a single item e.g. a letter or a number
• float: a decimal number
• integer: a whole number
• string: one or more characters

Question 2

Why are constants useful?

Answer 2

They protect from the value being accidentally changed and they can make a program easier to read and maintain.

Question 3

What is the difference between declaring and defining a variable?

Answer 3

Declaring a variable is creating it, whereas defining a variable is setting/changing it.

Question 4

Why is it important to give variables meaningful names?

Answer 4

• more readable
• easier to maintain
• easier to debug

Question 5

What are some common naming conventions?

Answer 5

• camelCase
• snake_case
• PascalCase

Question 6

What is a reserved word?

Answer 6

A set of words that cannot be used as identifiers, including instructions of the programming language.

Question 7

What is the difference between local and global variables?

Answer 7

These are known as the scope of a variable, which refers to what parts of the program can access the data stored by the variable. Global variables are accessible throughout the entire code, whereas local variables are only accessible within the function they are declared in.

Question 8

Why is it better to use local variables in a function rather than global?

Answer 8

They are more efficient as they only take up memory when the subprogram is running. They also increase code security as the values can only be accessed and altered within specific sections of the code.

Question 9

What are the standard arithmetic operators?

Answer 9

• • adds one value to another
• • subtracts one value from another
• / divides one value by another
• • multiplies one value by another
• % returns the remainder of dividing one value by another
• DIV (integer division) divides one value by another, ignoring any remainder

Question 10

What is a relational operator and what are the standard relational operators.

Answer 10

They allow us to compare values and return either true or false.
- == returns true if both values are the same
- != returns true if both values are not the same
- = sets the value of a variable
- > returns true if a value is greater than another
- < returns true if a value is less than another
- >= returns true if a value is greater than or equal to another
- <= returns true if a value is less than or equal to another

Question 11

What is a logical operator and what are the standard logical operators?

Answer 11

Allow multiple relational operators to eb combined for more complex expression.
- AND returns true if both conditions together are true
- OR returns true if either condition (or both) is true
- NOT returns true if the condition is false and vise versa

Question 12

What is a function?

Answer 12

A named section of code that performs a set task when called. they are used to make code more readable, maintainable and reusable.

Question 13

What is a library and what are their advantages/disadvantages?

Answer 13

A collection of predefined code that can be used in programs.
adv:
- saves time
- code in libraries have been extensively tested
disadv:
- you are relying on code someone else has produced

Question 14

What are some common built-in arithmetic functions?

Answer 14

• random number generation
• generating a range of numbers
• rounding numeric values

Question 15

What are some common built-in string handling functions?

Answer 15

• returning the length of a string
• extracting characters from a string
• returning substrings
• concatenation (joins two or more strings together)
• conversion (strings to arithmetic values)
• truncation (trims a string to a specified length)

Question 16

What are some common built-in general purpose functions?

Answer 16

• input/output
• file handling

Question 17

What are some functions of file handling and the modes of files?

Answer 17

functions:
- open opens a file for reading or writing
- close closes a file so that other programs can use it
- read reads data from a file into RAM
- write writes data from RAM to a file

modes:
- read allows data to be read from the file but not changed
- write allows data to be written to a file overwriting previous content
- append adds new data to the end of the file, leaving previous data unchanged

Question 18

What is validation and why is it important?

Answer 18

Checks that data input into a system meets a series of requirements. It is only as good as the criteria used. It ensures code is secure and can prevent cybercriminals from doing serious damage.

Question 19

What is verification?

Answer 19

Checks that no errors have been introduced when data is input.

Question 20

What are the types of validation check?

Answer 20

1. Data type check: checks that data is the correct type
2. Range check: checks that data is within a set range
3. Length check: checks that the number of characters in a string is within the predefined range
4. Presence check: checks whether data is present or not
5. Format check: checks whether data is in a predefined format e.g. dd/mm/yy for dates
6. Spelling check: checks whether words can be found within a predefined dictionary
7. Constraints check: rules than an input must meet
8. Check digits: a character that is calculated based on the value of a specified piece of data using an algorithm. If the character is different from the stored value, it is invalid.

Question 21

What are some post-check actions?

Answer 21

Error handling allows software to manage invalid or unusual inputs.
Error reporting provides useful information to inform users of what is correct, or to help a programmer debug their code

Question 22

What are the three basic control structures?

Answer 22

1. Sequence: when instructions run one after another
2. Selection: when a program can branch into different sequences depending on the condition
3. Iteration: when a part of a program loops until a condition is met, or sometimes forever

Question 23

What is the difference between pre-condition and post-condition loops and what are some examples?

Answer 23

A pre-condition loop is when the condition determining if the loop will run takes place at the beginning of the loop e.g. for loops and while loops. A post-condition loops is when the condition determining if the loop will run takes place at the end of the loop e.g. repeat… until loops.

Question 24

What are some examples of data structures?

Answer 24

• array
• list
• record
• set

Question 25

What is an array and what are their advantages and disadvantages?

Answer 25

They store multiple values of the same type of data.

adv:
- efficient
- high performance
- easy to implement/understand

disadv:
- inflexible as they are fixed and limited to only one type of data

Question 26

What is a list and what are their advantages and disadvantages?

Answer 26

They are like an array but can store multiple different types of data.

adv:
- flexible as they are dynamic and can store different data types
- efficient use of available memory
- quick reordering of stored values as only pointers need to be changed

disadv:
- slower than arrays
- can be complex to implement

Question 27

What is a record?

Answer 27

An ordered collection of elements in which each element is called a field. Each field has a name and a data type.

Question 28

What is a set?

Answer 28

Data that is grouped according to ownership of different sets. They allow us to organise and filter data very quickly.

Question 29

What is a bubble sort?

Answer 29

A sorting algorithm that compares each adjacent value in a list and swaps them if necessary. It continually passes through the list until no more swaps are made, at which point it is sorted.

Question 30

What is an insertion sort?

Answer 30

A sorting algorithm that compares each value with the value to its left and moves it left until it is in the correct position. This algorithm sorts through data in one pass.

Question 31

What is a quick sort?

Answer 31

An algorithm that uses an element of a list as the pivot and splits the list into two sublists. The elements higher than the pivot go in one sublist and elements lower than the pivot go in the other sublist. These sublists are then quick sorted until each sublist only has one element. These sublists are then combined to create one ordered list.

Question 32

What are the advantages and disadvantages of a bubble sort?

Answer 32

Adv:
- simple, easy to understand and implement

Disadv:
- inefficient, takes a long time to complete if the data is in reverse order

Question 33

What are the advantages and disadvantages of an insertion sort?

Answer 33

Adv:
- simple, easy to understand and implement
- doesn’t require lots of additional memory to run

Disadv:
- inefficient, takes a long time to complete for large quantities of data

Question 34

What is a linear search?

Answer 34

An algorithm that compares elements in a list one at a time with the search data until a match is found.

Question 35

What is a binary search?

Answer 35

An algorithm that takes the middle element of a list and compares it with the search data. If it is not a match, it then determines whether the search data is higher or lower in value than the element and will binary search data on either side of the middle element accordingly.

Question 36

What are the advantages/disadvantages of a linear search?

Answer 36

Adv:
- simple, easy to understand and implement
- doesn’t require data to be sorted
- quick for small data sets

Disadv:
- inefficient, can be slow for large data sets

Question 37

What are the advantages/disadvantages of a binary search?

Answer 37

Adv:
- efficient, tends to be quicker than a linear search

Disadv:
- data must be sorted in advance

Question 38

What is a count occurrence?

Answer 38

Works like a linear search but instead of ending when the search data is found, it counts every time the search data occurs. Unless the data is sorted, it must run through the entire data set.

Question 39

What is recursion?

Answer 39

When a function calls itself

Question 40

What is a stack?

Answer 40

A LIFO data structure in which only the top item of data can be added (pushed) or removed (popped) from the stack.

Question 41

What is a queue?

Answer 41

A FIFO data structure in which data can only be added (enqueued) to the tail of the queue and can only be removed (dequeued) from the head of the queue. This ensures fair access to resources.