Applications generation

Question 1

What are applications?

Answer 1

• Software that is designed to perform a specific task or a task for the user

Question 2

Examples of applications and their purposes

Answer 2

• Word processor: for creating, editting and printing text documents
• Web browser: for browsing the web and accessing information online
• Spreadsheet software: for organising, calculating and analysing numerical data
• Antivirus: for protecting the computer system from viruses and other malicious software

Question 3

What is utility software?

Answer 3

• Software designed to help analyse, configure, optimise or maintain a computer
• It supports the operating system

Question 4

Examples of utility software

Answer 4

• Disk defragmentation: rearrange the files on a hard drive to increase efficiency
• File management: organise, search, rename and relocate files stored on the system
• Device driver: provide an interface between the hardware and operating system
• Security: protect the system from various threats like viruses and malware

Question 5

What is open source software and some examples?

Answer 5

• Users can view, modify and distribute the source code
• Ideal for collaborative projects, customisation and transparency

Question 6

What is closed source software and some examples?

Answer 6

• The source code is hidden and proprietary
• Ideal for businesses requiring intellectual property protection

Question 7

Pros and cons of open source software

Answer 7

• Pros to the creator: collaboration, community engagement, faster innovation
• Cons to the creator: less control, burdened with requests from the user
• Pros to the user: free, customisable and transparent
• Cons to the user: less user-friendly, compatability issues and more bugs

Question 8

Pros and cons of closed source software

Answer 8

• Pros to the creator: greater control, revenue through sales
• Cons to the creator: slower innovation, full resposibility for updates
• Pros to the user: professional support, consistency and polished products
• Cons to the user: costly and less cusomisable

Question 9

What is a translator and the main types?

Answer 9

• Translators convert source code from a high-level language to a low-level language
• The main types are:
• Interpreters
• Compilers
• Assemblers

Question 10

What do interpreters do?

Answer 10

• Interpret source code line by line and execute while interpreting
• Easier to debug, allows incremental testing and faster to start execution
• Slower overall execution time and interpreter must be present during execution

Question 11

What do compilers do?

Answer 11

• Translates the entire source code into machine code and executes it
• Faster execution time, no need for compiler during execution
• Longer initial compilation time and can be more challenging to debug

Question 12

What do assemblers do?

Answer 12

• Translate assembley language into machine code
• Assemblers deal with low level languages

Question 13

What is compilation and what are the 4 stages?

Answer 13

• A process that translates a program written in a high-level language into machine code
• Lexical analysis
• Syntax analysis
• Code generation
• Optimisation

Question 14

What is the process of lexical analysis?

Answer 14

• Unnecessary elements such as comments and white space is removed
• Lexical tokens are introduced
• Tokens represent common keywords in the programming language
• Reserved words are replaced with tokens
• Tokens are added to a token look up table
• Variables are stored for later use

Question 15

What is the process of syntax analysis?

Answer 15

• Incoming tokens from lexical analysis are checked to ensure that they conform to the rules of the programming language
• Lookup table is updated with the data type and scope of variables
• If errors are found, they are reported back AT THE END in an error report
• If the code passes, it creates an abstract syntax tree (AST)

Question 16

What is an abstract syntax tree?

Answer 16

• An “intermediate” representation of the program that is being analysed

Question 17

What is the process of code generation and optimisation?

Answer 17

• Takes the AST from the previous stage and converts it into objet code that can be executed by the computer
• During optimisation, the code is made more efficient without changing its functionality
• A common method of this is by removing duplicate code

Question 18

What are code libraries?

Answer 18

• A collection of pre-written code / functions / scripts
• They are packaged together to allow developers to perform common tasks without having to rewrite the code

Question 19

Benefits of using libraries

Answer 19

• Efficiency: saves time and effort
• Reliability: often tested and optimised already
• Reusability: same library can be reused
• Community support: strong support and communication

Question 20

Drawbacks of libraries

Answer 20

• Dependency issues: can lead to problems if the library is discontinued
• Compatability: different versions of the library of the system you are working on
• Overhead: can add unnecessary complexity and size to the application

Question 21

How are libraries used during compilation (linkers)

Answer 21

• Libraries are often compiled seperately and then linked to the code
• Static linking: libraries are combined with the code at compile time, creating a larger executable
• Dynamic linking: libraries are linked during runtime, allowing for more flexebility but requiring the library to be present during execution

Question 22

Role of a linker

Answer 22

• Combine different code files and libraries into a single executable. Resolve references between files

Question 23

Role of loaders

Answer 23

• System tools that load executable files into memory so they can be run by the operating system