2.1.7

Correcting Algorithms

Test yourself on Correcting Algorithms

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Correcting Algorithms

As well as knowing what an algorithm does, it's important to be able to fix it if it all goes wrong.

Incorrect identifiers

Incorrect identifiers

A common mistake in programs is incorrect identifiers.
Be very careful with uppercase and lowercase letters.
Be careful with similar looking characters:
- 0 and O.
- 1 and l (lower case L).

Incorrect operators

Incorrect operators

Look out for the difference between similar operators such as testing if a number is less than another, rather than less than or equal to the other.

Missing processes

Missing processes

Sometimes a line of code has been forgotten, which can lead to issues such as infinite loops, where the code will never end.

Examples of how to Correct Algorithms

Incorrect identifiers

Incorrect identifiers

In this example, there is a problem on line 1.
Weather has initially been misspelt.
If the program were to run, the programmer would see an error indicating that there is no variable named waether. So, the program can not see if the value of sun is stored within the weather variable.

Incorrect operators

Incorrect operators

This code determines whether a number is odd or even.
- A number is even if it is EXACTLY divisible by 2 with NO REMAINDER.
The error is on line 3.
Whilst >= does include 0, it also includes the only other answer of 1.
If this program were to be run, all numbers would be shown as even.
To fix the code, we need to replace > with =

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 Correcting Algorithms

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

1
Common mistakes in algorithms include:Fill in the list
2
Which of these characters gets most commonly confused in programming?Multiple choice
3
What is the most common operator mistake?Multiple choice
4
When reviewing an algorithm with incorrect identifiers, what should be closely examined to prevent errors?Multiple choice
5
In identifying errors related to operators& comma; what should be carefully verified within a conditional statement?Multiple choice

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Interpreting Algorithms

Completing Algorithms