Week 1

Question 1

When was the invention of the Diffrence Engine

Answer 1

1822

Question 2

How many stages have the computer languages of the last fifty years come to

Answer 2

Two: The first major language and the second major languages

Question 3

What is a programming language

Answer 3

A programming language is an artificial
language designed to express computations or
algorithms that can be performed by a
computer

Question 4

What is a program

Answer 4

A program is computer coding of
an algorithm that
– Takes input
– Performs some calculations on
the input
– Generates output

Question 5

factorial program in C

Answer 5

int fact(int n) {
int sofar = 1;
while (n>0) sofar *= n–;
return sofar;
}

Question 6

Master the von Neumann Architecture

Question 7

Key Features of von Neumann Architecture

Answer 7

• Data and programs stored in memory
  – Instructions and data are piped from memory to CPU
  – Fetch-execute-cycle for each machine instruction

Question 8

Describe the fetch-execute cycle

Answer 8

initialize the program counter (PC)
repeat forever
fetch the instruction pointed by PC
increment the counter
decode the instruction
execute the instruction
end repeat

Question 9

Mention some programmnig languages that mimic von neumann architecture

Answer 9

C, C++ Java

Question 10

How do these programming languages micmic the von neumman architecture

Answer 10

– Variables → memory cells
– Assignment statements → data piping between
memory and CPU
– Operations and expressions → CPU executions
– Explicit control of execution flows → prog. counter

Question 11

The architecture is limited by?

Answer 11

Allow efficient mapping between language and
hardware for good execution performance, but
limited by von Neumann bottleneck

Question 12

How old is LISP

Answer 12

LISP is the second oldest general programming language
that is still in use since 1958

Question 13

Give a summary of imperative langauge

Answer 13

– Variables, assignment statements, and iteration
– Include languages that support object-oriented
programming, scripting languages, visual languages
– Ex.: C, Java, Perl, JavaScript, Visual BASIC .NE

Question 14

Give a summary of functional language

Answer 14

– Computing by applying functions to given parameters
– Ex.: LISP, Scheme, ML

Question 15

Give a sumary of logic language

Answer 15

– Rule-based (rules are specified in no particular order)
– Ex.: Prolog

Question 16

Mention the Programming Design Methodology

Answer 16

• 1950s and early 1960s: simple applications; worry
  about machine efficiency (FORTRAN)
• Late 1960s: people efficiency important;
  readability, better control structures (ALGOL)
  – Structured programming, free format lexical
  – Top-down design and step-wise refinement
• Late 1970s: process-oriented to data-oriented
  – Data abstraction
• Middle 1980s: object-oriented programming
  – Data abstraction + inheritance + dynamic binding

Question 17

What makes a good PL

Answer 17

• Readability: the ease with which programs can
  be read and understood
• Writability: the ease with which a language
  can be used to create programs
• Reliability: a program performs to its
  specifications under all conditions
• Cost

Question 18

Mention features related to readablity

Answer 18

Overall Simplicity
Orthogonality
Control Statements
Data types and structures
Syntax consideration

Question 19

Mention features related to writability

Answer 19

Simplicity and orthogonality
Support for abstraction
Expressivity

Question 20

Mention features related to reliablity

Answer 20

Type checking
Exception handling
Aliasing
Readability and writability

Question 21

Mention features related to cost

Answer 21

Training programmers to use language
Compiling programs
Executing programs: runtime type checking
Language implementation system
reliability: poor reliability leads to high cost
Maintaining programs

Question 22

Mention other things that make a good PL

Answer 22

• Portability
  – The ease with which programs can be moved from
  one implementation to another
• Generality
  – The applicability to a wide range of applications
• Well-definedness
  – The completeness and precision of the language’s
  official definition
• Power efficiency?

Question 23

Describe compilation

Answer 23

Translate a high-level program into equivalent
machine code automatically by another program
(compiler)

Question 24

Mention the phase of compilation

Answer 24

Lexical analysis: converts characters in the source
program into lexical units
– Syntax analysis: transforms lexical units into parse
trees which represent syntactic structure of program
– Semantics analysis: generate intermediate code
– Code generation: machine code is generated
– Link and load

Question 25

Describe interprtation

Answer 25

• Program interpreted by another program
  (interpreter) without translation
  – Interpreter acts a simulator or virtual machine
• Easier implementation of programs (run-time
  errors can easily and immediately displayed)
• Slower execution (10 to 100 times slower than
  compiled programs)
• Often requires more space
• Popular with some Web scripting languages (e.g.,
  JavaScript)