March Mock

What is representational abstraction?

A technique in which excessive details are removed to arrive at a representation of a problem that consists of only the key features

What is abstraction by generalisation?

The grouping together of similarities within a problem to identify what kind of problem it is

What is data abstraction?

When details about how data is being stored are hidden

What kind of problems make use of multiple levels of abstraction?

Large complex problems

How does abstraction allow non-experts to make use of a system?

Hides complex and irrelevant information in abstract models

Advantages of using abstraction in software development?

Easier for to focus on core elements

Reduces the time needed to be spent on the project

Prevents program from getting unnecessarily large

Applications of layers of abstraction

Networking

Programming languages

Advantages of using abstraction in programming languages?

Easier to remember syntax in high level languages

Coding becomes accessible to beginners

How does object oriented programming use abstraction?

Objects are an abstraction for real-world entities

Attributes are an abstraction for the characteristics of an object

Methods are ab abstraction for the actions a real-world object is able to perform

What is the difference between abstraction and reality?

Abstraction is a simplified representation of reality

What is a decision?

A decision is a result reached after consideration

When are decisions made?

A decision is made whenever a choice is needed

What is the shape given to a decision icon in a flow chart?

A diamond

In a flowchart how many options can be chosen from a decision?

2 different options

How are effective decisions made?

By evaluating the importance of different factors and selecting options which satisfy the needs of the task the most appropriately

Does the result of a decision affect the flow of a program?

The program will follow a different route depending on the decision made by the user

What are the programming constructs?

Sequence

Branching

Iteration

What categories of loop is iteration split up into?

Count-controlled

Condition-controlled

How does branching work?

A certain block of code is run if a specific condition is met using IF statements

What is recursion?

A programming construct in which a sub routine calls itself during its execution until the base condition is met

What is the base case in recursion?

A condition that must be met in order for the recursion to end

Advantages of recursion?

Can be represented in fewer lines of code

Easier to express some functions recursively than using iteration

Disadvantages of recursion?

Inefficient use of memory

Danger of stack overflow

Difficult to trace

What information is stored on the call stack?

Parameters

Return addresses

Local variables

What is a scope?

The section of the program in which a variable is accessible

Advantages of using local variables over global variables?

Less memory is used

Self-contained so unaffected by code outside of the sub routine

Take precedence over global variables with the same name

What is top down design?

A technique used to modularise programs in which the problem is continually broken down into sub problems until each can be represented as an individual, self-contained module which performs a certain task

Advantages of modular design?

Makes a problem easier to understand and approach

Simpler to divide tasks between a team

Easier to manage project

Self-contained modules simplify testing and maintenance

Greater reusability

Another name for top down design?

Stepwise refinement

What is the difference between procedures and functions?

Functions must always return a single value while a procedure does not always have to return a value

What does it mean to pass a parameter to a subroutine by reference?

The address in memory of the parameter is passed to the subroutine so it’s value outside of the subroutine will be updated

Features of IDEs?

Stepping

Variable watch

Breakpoint

Source code editor

Debugging tools

What does IDE stand for?

Integrated Development Environment

What is encapsulation OOP?

When attributes are declared as private so can only be accessed and edited by public methods

Purpose of encapsulation OOP?

Program complexity is reduced by protecting data from being accidentally edited by other parts of the program

What is meant by a computable problem?

A problem that can be solved using an algorithm

What are the limiting factors to computable problems?

Processing power

Processor speed

Computer memory

Time

What are the factors to be considered during the problem definition phase?

Strengths and weaknesses of current solution

Volume/ type/ frequency/ nature of inputs outputs and stored data

What is problem decomposition?

When problems are continually broken down until each subproblem can be represented as a subroutine

Purposes of problem decomposition?

Save time coding

Simplify project management

Simplify testing and maintenance

Faster project delivery

Develop sections in parallel

How does the divide and conquer technique work?

The problem size is halved with every iteration. Each individual subproblem is then solved recursively. The solutions to the subproblems are then recombined to form the final solution to the problem

What are the applications of divide and conquer?

Merge sort

Binary search

Quick sort

What is representational abstraction?

A computational technique in which excessive details are removed to simplify a problem

What are examples of problem solving techniques?

Abstraction

Divide and conquer

Visualisation

Pipelining

Data mining

How does backtracking work?

By methodically visiting each path and building a solution based on the paths found to be correct. If a path is found to be invalid at any point it backtracks to the previous stage and visits an alternate path

What are the advantages of using performance?

Safe

Relatively inexpensive

Less time-consuming

What is an algorithm?

A series of steps that complete a task

What is a linear search algorithm?

An algorithm which traverses through every item one at a time until it finds the item it’s searching for.

What is the binary search algorithm?

A divide and conquer algorithm which means it splits the list into smaller lists until it finds the item it’s searching for since the size of the list is halved every time

What is the bubble sort algorithm?

It passes through the list evaluating pairs of items and ensuring the larger value is above the smaller value

What are programming paradigms?

Different approaches to using a programming language to solve a problem

What are the categories for programming paradigms?

Imperative and delcarative

What are the advantages of procedural programming?

Can be applied to a wide range of problems

Relatively easy to write and interpret

What are the uses of declarative programming?

Expert systems

Artificial Intelligence

How does assembly language differ from machine code?

Assembly language uses mnemonics rather than binary. One line in assembly language is equal to one line in machine code

What is a class?

A template for an object that defines the state and behaviour of an object. An object is an instance of a class.

What are the disadvantages of OOP?

Requires a different style of thinking which can be difficult for programmers accustomed to other paradigms to pick up.

OOP may not be suited to all types of problems

Generally unsuitable for smaller problems

In hashing what is a collision?

When two key maps have the same hash

What is hashing?

The process of turning an input into a fixed size value

What is a hash table?

A data structure that uses hashing to store information with constant lookup time

What are the properties that a hashing algorithm should have?

Low chance of collision

Quick to calculate

Output smaller than input

What data type should be used for storing a phone number?

String

What is a string?

A data type that stores a collection of characters

What is boolean?

A data type that stores just True and False

What is an array?

An ordered, finite set of elements of a single type

What is a record made up of?

Fields

What is a list?

A data structure consisting of a number of items in which the items can occur more than once

What are the main differences between arrays and lists?

Lists can store data non-contiguously whereas arrays store data in order

Lists can store data of more than one data type

What is a tuple?

An immutable ordered set of values of any type

What is the difference between a tuple and an array?

Tuples are initialised using regular brackets instead of square brackets

What is a linked list?

A dynamic data structure used to hold an ordered set of items which are not stored in a contiguous location

What does each node in a linked list contain?

It contains a data field, which stores the actual data, and another address field called a pointer, which contains the address of the next item in the list

What is a graph?

A graph is a data structure consisting of a set of vertices connected by edges

What is a directed graph?

A graph in which the edges can only be traversed in one direction

What is a weighted graph?

A graph in which the edges have a cost to traverse

What data types can a computer understand as a graph?

Adjacency matrix

Adjacency list

What are the advantages of using an adjacency matrix?

Convenient to work with

Easy to add new nodes

What are the advantages of using an adjacency matrix?

Space efficient for large sparse networks

What is a stack?

A last in first out data structure where items can only be removed from and added to the top of the list

Examples of where stacks may be used?

Back button in a web page

Undo buttons

What is a queue?

A first in first out data structure where items are added to the end of the queue and removed from the front of the queue

What is a tree?

A data structure which has a root node and child nodes connected with branches

What is a binary tree?

A type of tree in which each node has a maximum of two children

What is the purpose of a binary tree?

It is used to search for values quickly

What properties does a good hashing algorithm have?

A good hashing algorithm must be fast and have a low chance of collision

What is De Morgan’s law?

not(A and B) = not A or not B

What is the purpose of a D type flip flop?

To store the value of a single bit

When is the stored value in a D-type flip flop updated?

On the rising edge of the clock signal

What is the law of distribution?

The law of distribution states that for all numbers a, b, and c, a (b + c) = (a b) + (a * c)

What is the law of association?

The addition or removal of brackets and reordering of literals in a boolean expression

What is the law of commutation?

It shows that the order of literals around an operator does not matter

What is the law of double negation?

If you negate a literal twice you can remove both negations and retain the same truth value