Transcript CGS 3460 PROGRAMMING USING C

CGS 3460
PROGRAMMING USING C
Spring 2007
Instructor: Rong Zhang
TAs: Ting Chen and Sungwook Moon
Goals
• We will learn
– Read: Understand programs written in C language
– Write: Design and implement programs using C language
– Compile: Use compiler to convert C code into executable file
under UNIX
– Execute: Run corresponding code to get results
– Debug: Identify and fix syntax and semantic errors in C code.
• Appropriate for
– Technically oriented people with little or no programming
experience
– Experienced programmers who want a deep and rigorous
treatment of the language
New View of Computers
• From a programmer’s viewpoint
– Computers are tools
– A computer program turns raw data into
meaningful information
– A program is the driving force behind any job
that any computer does
• A program is a list of detailed instructions
• These instructions are written in certain
programming language
Available Programming Languages
• Machine Languages
• Assembly Languages
• High-level Languages
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C/C++
COBOL
Pascal
BASIC
Fortran
JAVA
Etc.
Machine Languages
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System of instructions and data directly
understandable by a computer's central
processing unit.
Example:
100011 00011 01000 00000 00001 000100
000010 00000 00000 00000 10000 000001
000000 00001 00010 00110 00000 100000
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Every CPU model has its own machine code,
or instruction set, although there is
considerable overlap between some
Assembly Languages
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Human-readable notation for the machine
language that a specific computer architecture
uses representing elementary computer
operations (translated via assemblers)
Example:
load hourlyRate
mul workHours
store salary
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Even into the 1990s, the majority of console
video games were written in assembly
language.
High-level Languages
• Higher level of abstraction from machine
language
– Codes similar to everyday English
• Use mathematical notations (translated
via compilers)
– Example:
salary = hourlyRate * workHours
• Make complex programming simpler
Why Programming using C
• Initial development occurred at Bell Labs in early
70’s by Ritchie
• General-purpose computer programming
language
– high-level assembly
– Simplicity and efficiency of the code
• The most widely used programming languages
– Commonly used for writing system software
– Widely used for writing applications
– Hardware independent (portable)
• Great influence on many other popular
languages
Textbooks
• Required
Programming in C (3rd Edition) by Stephen Kochan.
ISBN: 0672326663. Link for the book from amazon:
http://www.amazon.com/gp/product/0672326663
• Recommended Reading
Absolute Beginner's Guide to C by Greg Perry. ISBN:
0672305100. Link
http://www.amazon.com/gp/product/0672305100
Outline of the Course – I
• Introductions
– Familiarization with programming environment, telnet / SSH Secure
Shell, ftp / SSH Secure File Transfer, UNIX, Compiling / gcc
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C program structure
Basic data types and variables declaration
Arithmetic expressions and operators
Control statements.
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Conditional statements
The while loop
The do while loop
The for loop
The if else statement
The switch statement
The break statement
The continue statement
Outline of the Course – II
• Formatted Input and Output
• Arrays and Strings
• Functions
– Declarations
– Calling
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Pointers
Struct, Union, Enums
Preprocessor
* Advanced Material
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Debug using gdb
Arrays and Pointer Arithmetic
Binary Trees
Link Lists
Recursive Functions
* may be adjusted according to time and interests of students
Grading Scale
• You earn your grade
• Final grade is calculated according to the
following schedule
Home works
Quizzes
Mid-term exam
Final exam / Project
30%
20%
20%
30%
• Grade scale is:
A(100-90),B+(89-85),B(84-80),C+(79-75),
C(74-70),D+(69-65),D(64-60),F(59-0)
Policies
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Attendance and Expectations
Homework Policies
Make-up Exam Policy
Other Policies
– Re-grading
• Course is on WebCT
http://lss.at.ufl.edu/services/webct/
History - I
• The first freely
programmable binary
computer
• Konrad Zuse's in
Germany
• Innovations
– Floating-point arithmetic
– High-capacity memory
– Modules or relays
operating on the yes/no
principle.
Konrad Zuse's Z1 Circa 1936
From http://inventors.about.com/library/blcoindex.htm
History - II
• The first electronicdigital computer
• Iowa State University
• Innovations
– A binary system of
arithmetic
– Parallel processing
– Regenerative memory
– Separation of memory
and computing functions
Atanasoff-Berry Computer
From http://inventors.about.com/library/blcoindex.htm
History- III
• ENIAC I (Electrical Numerical
Integrator And Calculator)
• John Mauchly and J Presper
Eckert
• 500,000 dollars
• Thousand times faster
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17,468 vacuum tubes
70,000 resistors
10,000 capacitors, etc
800 square feet floor space
30 tons
160 kilowatts of electrical power
The ENIAC 1946
From http://inventors.about.com/library/blcoindex.htm
History- IV
• First home computer
– Scelbi
– Mark-8 Altair
– IBM 5100 Computers
• 1974/1975
• Altair
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8080 CPU
256 Byte RAM card
$400
The consumer needs to put them
together, make it work and write
any needed software.
– Paul Allen and Bill Gates develop
BASIC for the Altair 8800
From http://inventors.about.com/library/blcoindex.htm
Mark-8 Altair
History- V
• Personal computer
– IBM PC in 1981
– Apple Macintosh in
1984
– Microsoft Windows 1.0
ships in November,
1985
– Network
http://www.pbs.org/nerds/timeline/
original IBM PC 1981
Operating System
• What is OS?
– A program that allows you to interact with the
computer -- all of the software and hardware
• With a command-line operating system (e.g., DOS)
• With a graphical user interface (GUI) operating system (e.g.,
Windows)
• Two major classes of operating systems
– Windows
• Nice interface, easy to learn
– Unix
• reliable timesharing operating system
Why we choose UNIX
• Powerful
– Multi-user operating system
– Good programming tools
• Most heavy-duty database management systems started out
on Unix
• Flexible
– Thousands of tools that can be combined and
recombined.
• Reliable
– Unix is hard to crash.
How to Access a UNIX Machine
telnet / ftp
Your personal computer
(client)
grove.ufl.edu
(server)
telnet: allows you to connect to other computers and use softwares
there
ftp: allows you to retrieve files from other computers.
Telnet
• TELetype NETwork
– A network protocol used on the Internet / LAN
– By extension, refers to the program which provides
the client part of the protocol
• Once connected
– Log on as a regular user with access to
• application / software
• data
• A Telnet command request looks like this
– telnet grove.ufl.edu
FTP
• File Transfer Protocol
– A network protocol used on the Internet / LAN
– Allow to transfer files to and from remote
computers
• A ftp command request looks like this
– ftp grove.ufl.edu
SSH
• Why SSH
• Download SSH
– http://www.openssh.org/
Figures from http://www.suso.org/docs/shell/ssh.sdf
More about SSH
• Recommendation for Windows
– Putty as telnet tool
• http://www.chiark.greenend.org.uk/~sgtatham/putty/download
.html
– WinSCP as ftp tool
• http://winscp.net/eng/download.php
• Other choices
– ftp, telnet using command line in windows
– Other softwares
• Core FTP
http://www.coreftp.com/download.html
Your First Program
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
Preprocessor: interact with
input/output of your computer
You will see this at the
beginning of nearly all
programs
Tells computer to load file
named <stdio.h>
<stdio.h> allows standard
input/output operations
Your First Program
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
Preprocessor: interact with
input/output of your computer
Start point of the program
C programs contain
one or more functions,
exactly one of which
must be main
int means that the
function main will
"return" an integer
value
Your First Program
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
Preprocessor: interact with
input/output of your computer
Start point of the program
Start and finish of function
Your First Program
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
Preprocessor: interact with
input/output of your computer
Start point of the program
Start and finish of function
Printing a line of Text
Your First Program
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
Preprocessor: interact with
input/output of your computer
Start point of the program
Start and finish of function
Printing a line of Text
New line character
Your First Program
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
Preprocessor: interact with
input/output of your computer
Start point of the program
Start and finish of function
Printing a line of Text
Finish and return value 0
A way to exit a function
It means that the program
terminated normally in this
case
Comments for programs
• Why need comments
– Good habit
– Readable to others
– Remind yourself
• How to comment
– /* … */
– // …
• Effects on compiler
• Examples
Compiler
• What is compiler
– A computer program (or set of programs) that
translates text written in a computer language
( the source code) into another computer
language (most time the executable file)
• Why we need a compiler
• Available C compiler in UNIX system: gcc
gcc sourcefile.c –o exefile.exe
Text Editor in UNIX
• Edit your code Using wordpad, MS word
on your personal computer
– Need to transfer your program to UNIX
machine using ftp
• Edit your code in UNIX using
– vi
– pico
– emacs
Procedure
helloworld.c
#include <stdio.h>
int main()
{
printf("Hello World\n");
return 0;
}
This is your C program. Type
the code in any standard text
editor, and save it as
helloworld.c. Transfer it to
grove.ufl.edu if necessary
Type gcc helloworld.c –o helloworld.exe
C-compiler
helloworld.exe
0011 0000 1010 0110
1100 0110 1011 0101
1010 1110 0110 1110
to compile helloworld.c into
helloworld.exe using the gcc compiler
The gcc compiler generate
corresponding executable code
named helloworld.exe. The computer
can execute this machine readable
code if you type ./helloworld.exe