Application generation

Question 1

4 stages of compilation

Answer 1

1) Lexical analysis
2) Syntax analysis
3) Code generation
4) Code optimisation

Question 2

lexical analysis

Answer 2

• comments + whitespace removed
• tokens are created out of lexemes (keywords)
• tokens are assembled into a symbol table

Question 3

token examples

Answer 3

• id
• number

Question 4

syntax analysis

Answer 4

• An abstract syntax tree is built
• using the symbol table from lexical analysis
• checks for errors and reports them

Question 5

code generation

Answer 5

• machine code is created

Question 6

code optimization

Answer 6

• removes variables/subroutines that were never called
• used to improve efficiency
• reduces execution time
• makes the program use fewer resources/less memory

Question 7

compilation stage symbol table is created

Answer 7

lexical analysis

Question 8

library

Answer 8

pre-written, compiled, tested, and checked pieces of code
Written by other authors / already written
Containing useful routines

Question 9

benefits of libraries

Answer 9

• Save time…
  …because no need to rewrite the code
• Use the expertise of others…
• …to complete tasks that require specialist
  knowledge
• Has already been tested/the programmer doesn’t
  have to test it themselves
• Making debugging easier/saving time

Question 10

drawback of libraries

Answer 10

• Not written by the programmer
  …so introduces uncertainty