CS 460
Programming Languages
Fall 2010
Dr. Watts
(Week 2)
C Language Review
How do your open a file?
How do you dynamically allocate space?
Single item
Array of items
How do you “pass by reference”?
Input
Output
Swap function
What is a “local function”?
1 – 6 assignment numbers
C Review due Monday, 13 Sept, 11:59 pm –
yourlastname.c
1
Useful C Books
The C Programming Language
Second Edition
Brian W. Kernighan and Dennis M. Ritchie
Prentice Hall, 1988 – ISBN 0-13-110362-8
C – A Reference Manual
Fifth Edition
Samuel P. Harbison III and Guy L. Steele Jr.
Prentice Hall, 2002 – ISBN 0-13-089592-X
History of Programming
Languages
5+ generations of computing history
Dates
Signature Hardware
People
Companies
Languages
Milestones
2
Generation 0
Before 1940
Mechanical
Abacus
Slide Rule
Analytic and Difference Engines
Punch card
Charles Babbage, Lady Ada Lovelace, Blaise
Pascal, Herman Hollerith
“Programming by Screwdriver”
Dials, other mechanical devices
Concepts of subprograms and loops
Generation 1
1940’s
Electro-mechanical
Relays
Vacuum tubes
Alan Turing, Presper Eckert & John Mauchley,
John V. Atanasoff, John VonNeuman, Konrad
Zuse
American Tabulating Company (later IBM)
Machine Language
Plankakül
3
Generation 1 (continued)
Turing machine
Enigma Code
ENIAC
Stored program
design
Generation 2
1950’s
Transistors
IBM, Univac
Assembly Languages
Short code
Movement of computing from scientific
laboratory to real world
4
Generation 3
1960’s – 1980’s
Integrated Circuits
Bill Gates, Steve Wozniak & Steve Jobs
Microsoft, Wang, IBM, Apple
High Level Language
FORTRAN, COBOL, BASIC
LISP, Smalltalk, Prolog
Algol, Pascal
Ada
Generation 3 (continued)
First Compiler
First Interpreter
Algol 60 Specification
BNF – Bachus Naur Form (grammar spcification)
Standardization
Structured Programming
Nested Control Structures
Case Statement
Single Pass Compilation
Pascal
5
Generation 3 (continued)
Data Structures
Multi-processing Operating Systems
Arrays, Lists
Strings
Records
C / UNIX
Multi-user Operating Systems (time sharing)
Personal Computer
Microprocessor
BASIC
Apple, IBM PC & Microsoft DOS
Triumph of the Nerds: The Rise of Accidental Empires
Generation 3 (continued)
Dynamic Language
APL, SNOBOL
All-purpose Languages
PL/I – all current data structures
Ada – Department of Defense
Software Engineering
Before its time – slow compiler; slow development
Object-Oriented Programming
Smalltalk, Eiffel, C++, Java
6
Generation 4
1980’s – 2000’s
VLSI – very large scale integrated circuits
Distributed and Parallel Processing
World Wide Web
GUI Emergence – high powered graphics
Special Purpose Languages
Java, Visual BASIC, C#
HTML, Java/Swing, Action Script
Scripting Languages
Java Script, Python, PHP, Ruby
Generation 5
Still to come
Post silicon
Natural Languages
AI
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Implementation
Importance of Standards
Compilation vs interpretation vs hybrid
Components of language translation
Lexical analysis
Syntactical analysis
Semantic analysis
Intermediate code generation
Optimization
Target code generation
Portability
Programming Environments
Stand alone tools
Integrated Development Environments
IDEs
Turbo Pascal (Borland)
MS Visual C++
Code Warrior
MS .net
8
Thoughts on Computer
Programming Languages
The use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offence.
(Edsger Dijkstra)
Consistently separating words by spaces became a general custom about the tenth century A.D., and
lasted until about 1957, when FORTRAN abandoned the practice. (Sun FORTRAN Reference Manual)
Cobol has almost no fervent enthusiasts. As a programming tool, it has roughly the sex appeal of a
wrench. (Charles Petzold)
C++ is the only current language making COBOL look good. (Bertrand Meyer)
C++ has its place in the history of programming languages. Just as Caligula has his place in the history
of the Roman Empire. (Robert Firth)
Arguing that Java is better than C++ is like arguing that grasshoppers taste better than tree bark. (Thant
Tessman)
Java is, in many ways, C++--. (Michael Feldman)
If Java had true garbage collection, most programs would delete themselves upon execution. (Robert
Sewell)
It is practically impossible to teach good programming style to students that have had prior exposure to
BASIC; as potential programmers they are mentally mutilated beyond hope of regeneration. (Edsger
Dijkstra)
In my egotistical opinion, most people's C programs should be indented six feet downward and covered
with dirt. (Blair P. Houghton)
C++ is history repeated as tragedy. Java is history repeated as farce. (Scott McKay)
Unix and C are the ultimate computer viruses. (Richard P Gabriel)
Subprograms – why?
Why do we create subprograms?
Reusability
Modularity
Readability
Writeability
Software Engineering
Why are we studying subprograms (now)?
Recursion – advanced sorting
Scheme – a functional language
9
Subprogram components
Subprogram definition
Subprogram call
Describes interface and actions of the subprogram
Explicit request that subprogram be executed
Complies to defined interface
Subprogram header
Indicates type of subprogram
Indicates name of subprogram
Optionally, specifies list of parameters
Subprogram Header Examples
FORTRAN
Pascal
Procedure adder (parameters);
Function adder (parameters) : returnType;
C++
SUBROUTINE ADDER (parameters)
returnType adder (parameters);
returnType adder (parameters) { }
Python
Def adder (parameters) :
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Alternative Subprogram
Definitions
Function overloading
Within #ifdef, #else, and #endif
Nested subroutines
Within Python if statement
Other suprogram issues
Prototypes vs definitions
Subprogram vs method
Method associated with object of a class
Formal vs actual parameters
Why prototypes?
C, C++, Pascal
Formal – in function definition
Actual – in function call
Parameter profile
Number, order and types of formal parameters
11
More subprogram issues
Procedure vs function
Nested subprograms
Procedure – no return value
Function returns a value
Scoping issues
Local vs global variables
Function names and return
types
Function names
Return types
Scalar
Composite
12
Parameters
Formal parameters in subprogram description
Actual parameters in subprogram call
Positional parameters
Keyword parameters
Variable number of parameters
Default parameters
Parameter Passing Types
In mode, out mode, inout mode
Pass-by-value
Pass-by-result
In mode then out mode – value passed then “returned”
Pass-by-reference
Out mode – value is “returned”
Pass-by-value-result
In mode – value is passed
Inout mode – address is passed
Pass-by-name
Inout mode – actual name is substituted
13
Type checking parameters
Compile time checking
Type coalescing
Passing arrays
Passing base address
Passing copy of array
Passing multidimensional arrays
14
Parameter passing design
considerations
Efficiency
One-way or two-way data transfer
C++ vs C
C++ or C : pass by value
What will this do?
void Swap (int a, int b)
{
int t = a;
a = b;
b = t;
}
int x, y;
Swap (x, y);
15
C++ vs C
C++ : pass by reference
May “implicitly” pass and use address if two-way
transfer is needed
void Swap (int &a, int &b)
{
int t = a;
a = b;
b = t;
}
int x, y;
Swap (x, y);
C++ vs C
C : only pass by value
Must explicitly pass and use address if two-way
transfer is needed
void Swap (int * a, int * b)
{
int t = *a;
*a = *b;
*b = t;
}
int x, y;
Swap (&x, &y);
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