Chapter 10 - Programming Language Translators (1.2)

Question 1

What is a Translator?

Answer 1

A program that converts high level source code into low level object code so that it can be executed by a computer, input is source code and output is object code

Question 2

What are the 3 types of Translator?

Answer 2

1. Compiler
2. Interpreter
3. Assembler

Question 3

What is a Compiler?

Answer 3

Program that translates high level code into machine code all at once

Question 4

What are some advantages of a Compiler? (3)

Answer 4

1. Can be run without a translator
2. Object code is more secure
3. Don’t need to compile it when you want to run object code

Question 5

What are some disadvantages of a Compiler? (3)

Answer 5

1. Longer than using an Assembler or Interpreter
2. If changes need to be made then the whole program needs to be compiled again
3. Can only be executed on certain devices (specific to a certain processor and OS)

Question 6

When is a Compiler used? (2)

Answer 6

1. When a program needs to be run regularly with occasional change
2. When the object code produced is going to be sold to users

Question 7

What is an Interpreter?

Answer 7

Program that translates high level code into machine code line-by-line

Question 8

What are some advantages of an Interpreter? (2)

Answer 8

1. Stops whenever it detects an error, making it useful for debugging
2. More portable as code can be executed on a range of platforms

Question 9

What are some disadvantages of an Interpreter? (2)

Answer 9

1. Requires an interpreter to run on different devices
2. Code must be translated with an interpreter every time it’s executed

Question 10

When is an Interpreter used?

Answer 10

When you need to test sections of code to check for any errors

Question 11

What is Assembly code?

Answer 11

Low level language where each instruction translates to one machine code instruction, it’s platform specific

Question 12

What is an Assembler?

Answer 12

Translates assembly code to intermediate code (bytecode) so that it can be executed as machine code

Question 13

What are the 4 stages of compilation?

Answer 13

1. Lexical Analysis
2. Syntax Analysis
3. Code Generation
4. Optimisation

Question 14

What is Lexical Analysis?

Answer 14

Removes unnecessary spaces and comments and performs simple error checking, keywords, variables, and constants are replaced with tokens, information about token associated with each
keyword or identifier is stored in a symbol table

Question 15

What is Syntax Analysis?

Answer 15

Tokens analysed against the grammar and rules of the programming language, any that break the rules are flagged up as syntax errors and added to a list of errors, abstract syntax tree is then created (representation of source code)

Question 16

What is Code Generation?

Answer 16

Abstract syntax tree used to produce machine code

Question 17

What is Optimisation?

Answer 17

Searches through the code to make it more efficient so that it’s faster to execute

Question 18

What is a Static Linker?

Answer 18

Piece of software that is responsible for linking external modules and libraries included within the code, in a static linker, modules and libraries are added directly to the main file which increases its size and any external updates to modules and libraries don’t effect the program

Question 19

What is a Dynamic Linker?

Answer 19

Piece of software that is responsible for linking external modules and libraries included within the code, in a dynamic linker, addresses of modules and libraries are added to the file where they’re referenced so that when the program is run, the loader retrieves the program at the specified address so that it’s executed, files remain small and external updates can go to the main file

Question 20

What is a Loader?

Answer 20

Retrieves the library/sub-routine from the given memory location

Question 21

What are Libraries used for?

Answer 21

They provide a specialised range of functions which would usually take alot of time and effort to develop

Question 22

What is a Library?

Answer 22

Pre-compiled programs which can be used within other programs using static or dynamic linking, they’re ready to use, error free and can be reused within multiple programs