8. program construction

Question 1

What is an assembler?

Answer 1

Converts low level assembly language into machine code.

Question 2

What is an interpreter?

Answer 2

Converts high level language one line at a time into machine code and executes it.

Question 3

What is a compiler?

Answer 3

Converts high level language all at once into machine code for use at a later time.

Question 4

What are the stages of compilation?

Answer 4

• lexical analysis
• syntax analysis
• semantic analysis
• code generation
• code optimisation

Question 5

What happens during lexical analysis?

Answer 5

Spaces and comments are removed from the code. Identifiers, keywords and operators are replaced with tokens (a variable with a name and value). A symbol table is created, which stores the addresses of all variables, subroutines and labels used in the program.

Question 6

What happens during syntax analysis?

Answer 6

The tokens will be checked to see if they fit with the language’s syntax. If a syntax error is found, an error message will occur and the compiling will stop.

Question 7

What happens during semantic analysis?

Answer 7

Variables are checked to see if they are declared correctly and use a valid data type. Operations are checked to ensure they are correct for the data type used.

Question 8

What happens during code optimisation?

Answer 8

the code is optimised to make it faster and more efficient.

Question 9

What happens during code generation?

Answer 9

The code in is generated in machine code.