Chapter 1: Introduction

Question 1

Why are there so many programming languages?

Answer 1

• Evolution: we find better ways of doing things over time
• Special purposes: for different problem domains (C for low-level, Prolog for logical relationships)
• Personal preference (some people like to think recursively, others iteratively; some like pointers, etc.)
• Proprietary interests (Java)

Question 2

What makes a programming language successful?

Answer 2

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•Expressive power: good abstraction facilities; ability to write clear & maintainable code (C, Common Lisp, Perl)
•Short learning curve (BASIC, Pascal, LOGO, Scheme)
•Easy to implement: portable (BASIC, Forth)
•Standardization
•possible to compile to very good (fast/small) code (Fortran)
•backing of a powerful sponsor (COBOL, PL/1, Ada, Visual Basic)
•wide dissemination at minimal cost (Pascal, Turing, Java)

Question 3

Why do we have programming languages? Purpose?

Answer 3

• way of thinking – expressing algorithms
• languages from the user’s point of view
• abstraction of virtual machine – specifying what you want the hardware to do without getting down into the bits
• languages from the implementor’s point of view

Question 4

Why study programming languages?

Answer 4

(1) To help you choose the appropriate tool for the job
•C vs. Modula-3 vs. C++ for systems programming
•Fortran vs. APL vs. Ada for numerical computations
•Ada vs. Modula-2 for embedded systems
•Common Lisp vs. Scheme vs. ML for symbolic data manipulation
•Java vs. C/CORBA for networked PC programs
(2) To make better use of whatever language you choose
•Understand obscure features
•In C, help you understand unions, arrays & pointers, separate compilation, varargs, catch and throw
•In Common Lisp, help you understand first-class functions/closures, streams, catch and throw, symbol internals
•Figure out how to bring in powerful concepts from other languages into your language

Question 5

How are programming languages grouped?

Answer 5

Imperative & Declarative

Question 6

What are examples of “Imperative” languages?

Answer 6

• von Neumann (Fortran, Pascal, Basic, C)
• object-oriented (Smalltalk, Eiffel, C++?)
• scripting languages (Perl, Python, JavaScript, PHP)

Question 7

What are examples of “Declarative” languages?

Answer 7

• functional (Scheme, ML, Haskell)

* logic, constraint-based (Prolog,Make)

Question 8

What is “Pure Compilation”?

Answer 8

• The compiler translates the high-level source program into an equivalent target program (typically in machine language), and then goes away
• Better performance
• Compilation is translation from one language into another, with full analysis of the meaning of the input
• Compilation entails semantic understanding of what is being processed; pre-processing does not

Question 9

What is “Pure Interpretation”?

Answer 9

• Interpreter stays around for the execution of the program
• Interpreter controls the execution
• Greater flexibility
• Better diagnostics (error messages)
• Languages can have a mixture of compilation (JIT) and interpretation

Question 10

What is the difference between machine language and assembly language?

Answer 10

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Question 11

How are high-level languages an improvement on assembly language? When does it still make sense to program in assembler?

Answer 11

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Question 12

Name 3 von Neumann languages.

Answer 12

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Question 13

Name 3 functional languages.

Answer 13

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Question 14

Name 3 object-oriented languages.

Answer 14

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Question 15

Name 2 logic languages.

Answer 15

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Question 16

Name 2 widely-used concurrent languages.

Answer 16

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Question 17

What distinguishes declarative languages from imperative languages?

Answer 17

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Question 18

What organization spearheaded the development of Ada?

Answer 18

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Question 19

What is generally considered the first high-level programming language?

Answer 19

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Question 20

What was the first functional language?

Answer 20

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Question 21

How is interpretation different from compilation? What are the comparative advantages and disadvantages of the two approaches?

Answer 21

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Question 22

Is Java compiled or interpreted (or both)? How so?

Answer 22

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Question 23

What is the difference between a compiler and a preprocessor?

Answer 23

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Question 24

What was the intermediate form employed by the original AT&T C++ compiler?

Answer 24

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Question 25

What is P-code?

Answer 25

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Question 26

What is bootstrapping?

Answer 26

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Question 27

What is a just-in-time compiler?

Answer 27

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Question 28

Name 2 languages in which a program can write new pieces of itself “on the fly.”

Answer 28

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Question 29

Describe 3 “unconventional” compilers–compilers whose purpose is not to prepare a high-level program for execution on a microprocessor.

Answer 29

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Question 30

List 6 kinds of tools that commonly support the work of a compiler within a larger programming environment.

Answer 30

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Question 31

Explain how an IDE differs from a collection of command-line tools.

Answer 31

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Question 32

List the principle phases of compilation, and describe the work performed by each.

Answer 32

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Question 33

Describe the form in which a program is passed from:

scanner –> parser –> semantic analyzer –> intermediate code generator

Answer 33

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Question 34

What distinguishes the front end of a compiler from the back end?

Answer 34

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Question 35

What is the difference between a phase and a pass of compilation? When does it make sense for a compiler to have multiple passes?

Answer 35

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Question 36

What is the purpose of the compiler’s symbol table?

Answer 36

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Question 37

What is the difference between static and dynamic semantics?

Answer 37

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Question 38

On modern machines, do assembly language programmers still tend to write better code than a good compiler can? Why or why not?

Answer 38

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