paper 1 - lexical, syntax and semantic stages

Question 1

describe the syntax analysis stage

Answer 1

• tokens are checked to see if they match the spelling and grammar expected, using standard language definitions
• this is done by parsing each token to determine if it uses the correct syntax for the programming language
• if syntax errors are found, error messages are produced

Question 1

describe the lexical analysis stage

Answer 1

• comments and unneeded spaces are removed
• keywords, constants and identifiers are replaces by tokens
• a symbol table is created which holds the address of variables, labels and sub routines

Question 2

describe the semantic analysis stage

Answer 2

• variables are checked to ensure that they have been properly declared and used
• variables are checked to ensure they are of the correct data type (eg. float values are not being assigned to integers)