2.2.11

Arrays

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Arrays

Arrays are really useful when you have access to large amounts of related data, but you don't want to store in multiple variables.

Arrays

Arrays

Arrays are a data structure that stores a fixed number of values under a single identifier.
The values must be of the same type.

Array elements

Array elements

Each piece of data inside an array is called an element.
Each element has an index, which is its position within the array.
We start counting the indices from 0.

Arrays in pseudocode

Arrays in pseudocode

An array of ten items can be created using the following syntax:
- array name_of_array[10]
Values can be assigned as follows:
- name_of_array[0] = "Hello"
Values can be accessed as follows:
- print(name_of_array[0])

2D Arrays

A 2D array is the data structure which consists of an array of arrays.

2D Array

2D Array

A 2D array is a data structure where arrays are filled with other arrays.
This can be used to represent a 2D surface, or records.

Accessing elements

Accessing elements

To access an individual array, we can access the array as usual:
- array = my2DArray[4]
To access an individual element, we use this syntax:
- array[5][0]
This would get the first element of the sixth array.

Applications of 2D arrays

Applications of 2D arrays

2D arrays are often used to represent a 2D surface, for example a chess board:
- Each element of the 2D array could contain the chess piece in that location.
2D arrays can be used to represent a database:
- The outer array stores a collection of records.
- The inner arrays store a single record.

1

Computer Systems

1.1

Systems Architecture

1.1.1Fetch-Execute Cycle 1.1.2Common CPU Components & Their Function 1.1.3Von Neumann Architecture 1.1.4Factors Affecting CPU Performance 1.1.5Embedded Systems 1.1.6Exam-Style Questions - Von Neumann Architecture 1.1.7Diagnostic Misconceptions - Embedded vs General

1.2

Memory & Storage

1.2.1Types of Memory 1.2.2Flash Memory 1.2.3Properties of Flash Memory 1.2.4Running Out of Memory 1.2.5Virtual Memory 1.2.6Units of Capacity 1.2.7Calculating Capacity Requirements 1.2.8Solid State Storage 1.2.9Properties of Solid State Media 1.2.10Magnetic Storage 1.2.11Properties of Magnetic Media 1.2.12Examples of Magnetic Storage 1.2.13Optical Storage 1.2.14Properties of Optical Media 1.2.15Examples of Optical Storage 1.2.16Types of Optical Disk 1.2.17Number Bases 1.2.18Converting Number Bases 1.2.19Hexadecimal 1.2.20Using Hexadecimal 1.2.21Converting Denary & Hexadecimal 1.2.22Binary Addition 1.2.23Binary Shifts 1.2.24Representing Text 1.2.25ASCII & Unicode 1.2.26Representing Images 1.2.27Converting Binary & Images 1.2.28Representing Sound 1.2.29Data Compression 1.2.30Grade 9 - Storage 1.2.31Exam-Style Questions - Primary Memory 1.2.32Exam-Style Questions - Storage 1.2.33Exam-Style Questions - Data Conversions 1.2.34Diagnostic Misconceptions - RAM vs ROM 1.2.35Diagnostic Misconceptions - Bits, Nibbles & Bytes 1.2.36Diagnostic Misconceptions - Bits Required to Store 1.2.37End of Topic Test - Computer Systems 1.2.38End of Topic Test - Representation

1.3

Computer Networks, Connections & Protocols

1.4

Network Security

1.4.1Forms of Attack 1.4.2Penetration Testing 1.4.3Malware 1.4.4How Malware Spreads 1.4.5Social Engineering 1.4.6Phishing 1.4.7Cracking Passwords 1.4.8Denial of Service Attacks 1.4.9Data Interception 1.4.10Methods of Data Interception 1.4.11SQL Injection 1.4.12Network Administration 1.4.13Network Forensics 1.4.14Protecting Against Malware 1.4.15Firewalls 1.4.16User Access Levels 1.4.17Passwords 1.4.18Encryption 1.4.19End of Topic Test - Networks

1.5

Systems Software

1.5.1System Software 1.5.2Utility Software 1.5.3Operating Systems 1.5.4User Interfaces 1.5.5Memory & Process Management 1.5.6File Management 1.5.7Device Management 1.5.8User Management 1.5.9Encryption Software 1.5.10Defragmentation Software 1.5.11Data Compression Software 1.5.12Backup Software

1.6

Ethical, Legal, Cultural & Environmental Concern

2

Computational Thinking, Algorithms & Programming

2.1

Algorithms

2.1.1Computational Thinking - Abstraction 2.1.2Computational Thinking - Decomposition 2.1.3Algorithmic Thinking 2.1.4Pseudocode 2.1.5Flowchart Diagrams 2.1.6Interpreting Algorithms 2.1.7Correcting Algorithms 2.1.8Completing Algorithms 2.1.9Search Algorithms 2.1.10Binary Search 2.1.11Linear Search 2.1.12Overview of Sort Algorithms 2.1.13Bubble Sort 2.1.14Merge Sort 2.1.15Insertion Sort 2.1.16Exam-Style Questions - Sorting Algorithms

2.2

Programming Fundamentals

2.3

Producing Robust Programs

2.3.1Defensive Design 2.3.2Validation & Sanitisation 2.3.3Authentication & Contingencies 2.3.4Maintainability 2.3.5Purpose of Testing 2.3.6Types of Testing 2.3.7Test Plans 2.3.8Types of Errors 2.3.9End of Topic Test - Programming 2.3.10Exam-Style Questions - Testing

2.4

Boolean Logic

2.4.1Binary Systems 2.4.2Logic Circuits 2.4.3Boolean Logic 2.4.4Boolean Operators 2.4.5Grade 9 - Logic

2.5

Programming Languages & IDEs

2.5.1High-Level vs Low-Level Languages 2.5.2Translation - Compliers & Interpreter 2.5.3Translation - Assemblers 2.5.4Integrated Development Environments 2.5.5Exam-Style Questions - Translation

Jump to other topics

1

Computer Systems

1.1

Systems Architecture

1.1.1Fetch-Execute Cycle 1.1.2Common CPU Components & Their Function 1.1.3Von Neumann Architecture 1.1.4Factors Affecting CPU Performance 1.1.5Embedded Systems 1.1.6Exam-Style Questions - Von Neumann Architecture 1.1.7Diagnostic Misconceptions - Embedded vs General

1.2

Memory & Storage

1.2.1Types of Memory 1.2.2Flash Memory 1.2.3Properties of Flash Memory 1.2.4Running Out of Memory 1.2.5Virtual Memory 1.2.6Units of Capacity 1.2.7Calculating Capacity Requirements 1.2.8Solid State Storage 1.2.9Properties of Solid State Media 1.2.10Magnetic Storage 1.2.11Properties of Magnetic Media 1.2.12Examples of Magnetic Storage 1.2.13Optical Storage 1.2.14Properties of Optical Media 1.2.15Examples of Optical Storage 1.2.16Types of Optical Disk 1.2.17Number Bases 1.2.18Converting Number Bases 1.2.19Hexadecimal 1.2.20Using Hexadecimal 1.2.21Converting Denary & Hexadecimal 1.2.22Binary Addition 1.2.23Binary Shifts 1.2.24Representing Text 1.2.25ASCII & Unicode 1.2.26Representing Images 1.2.27Converting Binary & Images 1.2.28Representing Sound 1.2.29Data Compression 1.2.30Grade 9 - Storage 1.2.31Exam-Style Questions - Primary Memory 1.2.32Exam-Style Questions - Storage 1.2.33Exam-Style Questions - Data Conversions 1.2.34Diagnostic Misconceptions - RAM vs ROM 1.2.35Diagnostic Misconceptions - Bits, Nibbles & Bytes 1.2.36Diagnostic Misconceptions - Bits Required to Store 1.2.37End of Topic Test - Computer Systems 1.2.38End of Topic Test - Representation

1.3

Computer Networks, Connections & Protocols

1.4

Network Security

1.4.1Forms of Attack 1.4.2Penetration Testing 1.4.3Malware 1.4.4How Malware Spreads 1.4.5Social Engineering 1.4.6Phishing 1.4.7Cracking Passwords 1.4.8Denial of Service Attacks 1.4.9Data Interception 1.4.10Methods of Data Interception 1.4.11SQL Injection 1.4.12Network Administration 1.4.13Network Forensics 1.4.14Protecting Against Malware 1.4.15Firewalls 1.4.16User Access Levels 1.4.17Passwords 1.4.18Encryption 1.4.19End of Topic Test - Networks

1.5

Systems Software

1.5.1System Software 1.5.2Utility Software 1.5.3Operating Systems 1.5.4User Interfaces 1.5.5Memory & Process Management 1.5.6File Management 1.5.7Device Management 1.5.8User Management 1.5.9Encryption Software 1.5.10Defragmentation Software 1.5.11Data Compression Software 1.5.12Backup Software

1.6

Ethical, Legal, Cultural & Environmental Concern

2

Computational Thinking, Algorithms & Programming

2.1

Algorithms

2.1.1Computational Thinking - Abstraction 2.1.2Computational Thinking - Decomposition 2.1.3Algorithmic Thinking 2.1.4Pseudocode 2.1.5Flowchart Diagrams 2.1.6Interpreting Algorithms 2.1.7Correcting Algorithms 2.1.8Completing Algorithms 2.1.9Search Algorithms 2.1.10Binary Search 2.1.11Linear Search 2.1.12Overview of Sort Algorithms 2.1.13Bubble Sort 2.1.14Merge Sort 2.1.15Insertion Sort 2.1.16Exam-Style Questions - Sorting Algorithms

2.2

Programming Fundamentals

2.3

Producing Robust Programs

2.3.1Defensive Design 2.3.2Validation & Sanitisation 2.3.3Authentication & Contingencies 2.3.4Maintainability 2.3.5Purpose of Testing 2.3.6Types of Testing 2.3.7Test Plans 2.3.8Types of Errors 2.3.9End of Topic Test - Programming 2.3.10Exam-Style Questions - Testing

2.4

Boolean Logic

2.4.1Binary Systems 2.4.2Logic Circuits 2.4.3Boolean Logic 2.4.4Boolean Operators 2.4.5Grade 9 - Logic

2.5

Programming Languages & IDEs

2.5.1High-Level vs Low-Level Languages 2.5.2Translation - Compliers & Interpreter 2.5.3Translation - Assemblers 2.5.4Integrated Development Environments 2.5.5Exam-Style Questions - Translation

Practice questions on Arrays

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

1
Toggle until all are correct: Which of these is true of arrays?True / false
2
How do we access the first element of an array?Multiple choice
3
What would the command "array[5][3] = 0" do to a 2D array?Multiple choice

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