Language Translators: Full Compilers, Linkers, Interpreters, and Hybrid Implementations

Question 1

List the 4 fundamental phases of a typical compiler

Answer 1

1. lexical analyzer
2. syntatic analyzer
3. semantic analyzer & intermediate code generator
4. final code generator

Question 2

T/F: C++ and Ada are not fully compiled languages.

Answer 2

False, they are fully compiled

Question 3

What does the Lexical Analyzer do?

Answer 3

• Breaks the character stream into “words” called lexemes
• categorizes lexemes by token type
• detects lexical errors

Question 4

list some typical tokens

Answer 4

1. Identifiers
2. reserved words
3. numeric literals

Question 5

What are tokens equivalent to?

Answer 5

English parts of speech like verbs or nouns.

Question 6

What are lexical errors?

Answer 6

Sequences of characters that doesn’t represent valid tokens

Question 7

give an example of a lexical error

Answer 7

A question mark outside of a comment, character, or string literal is usually an error

Question 8

What does the syntactic analyzer do? (3)

Answer 8

• verifies syntax
• detects errors
• generates the parse tree

Question 9

T/F: Most compilation errors are syntax errors

Answer 9

True

Question 10

What is a typical example of a syntax error in most languages?

Answer 10

a missing semi-colon “;”

Question 11

What is a parse tree used for? what is this approach generally referred to as?

Answer 11

Intermediate code generation

syntax-directed translation.

Question 12

What does the Semantic Analyzer do?

Answer 12

Detects static semantic errors

Question 13

What are the most common semantic errors?

Answer 13

Mismatching types, like a non-boolean expression in an if statement.

Question 14

What does the intermediate code generator do?

Answer 14

Generates intermediate code.

Question 15

What is intermediate code?

Answer 15

a machine-independent low-level language that has no nested expressions or statements

Question 16

What phase is included in production compilers in regards to the semantic analyzer and intermediate code generator?

Answer 16

Optimizer

Question 17

T/F: The first 3 phases comprise the first pass of a compiler.

Answer 17

True

Question 18

What does the final code generator do?

Answer 18

generates machine-dependent object code or machine code

Question 19

T/F: The final code generator is often a 3rd pass over the complete program in its initially translated form.

Answer 19

False; 2nd

Question 20

The final code generator phase of the compiler typically involves ____ ____.

Answer 20

register allocation.

Question 21

What is the only phase of the compiler process that involves no error detection?

Answer 21

Final code generator

Question 22

T/F: Programs written in fully compiled languages must be linked before they can be run

Answer 22

True

Question 23

What don’t programmers often realize about linkers in IDEs

Answer 23

The linker automatically runs on a “build” command

Question 24

What does the linker do?

Answer 24

links together object files for programs made of multiple source files.

Question 25

What kind of programs do linkers usually apply to?

Answer 25

large programs

Question 26

What do linkers also link?

Answer 26

object libraries that come with the compiler

Question 27

What do object libraries contain?

Answer 27

I/O code, common math functions, and so on.

Question 28

When does a linker error occur?

Answer 28

When one source file refers to the name of another that cannot be found

Question 29

How do programs made from fully interpreted languages work in a nutshell?

Answer 29

They are translated and then executed by the interpreter

Question 30

T/F: interpreted languages always produce an executable file.

Answer 30

False; never produce.

Question 31

What runs slower, fully interpreted programs, or fully compiled programs? why?

Answer 31

fully interpreted programs

they need to be translated on every execution.

Question 32

What kind of errors do interpreted languages present? why?

Answer 32

run-time errors

there is no compilation time.

Question 33

What characterizes a hybrid implementation?

Answer 33

involving a compiler and interpreter

Question 34

The compiler in a hybrid implementation consists of the first ____ phases, which constitute the ____ of a traditional compiler.

Answer 34

three
first pass

Question 35

T/F: A hybrid implementation is completely machine-dependent.

Answer 35

False; independent

Question 36

in a hybrid implementation when does the interpreter part happen?

Answer 36

the second pass

Question 37

Initial implementations of ____ used this approach—the output of the compiler being referred to as ____.

Answer 37

Java
bytecode

Question 38

____ compilers are an alternative to the interpreter

Answer 38

Just-in-time

Question 39

Later ____ implementations replaced the interpreter with a just-in-time compiler

Answer 39

Java

Question 40

What makes just-in-time compilers different from interpreters?

Answer 40

They do extra compilation making the code execute faster