C LANGUAGE
219212 Programming Languages
Ms. Raviporn Yongchaitrakul
ID: 47541396
ABSTRACT

The C programming language was devised in the
early 1970s as a system implementation language for
the nascent Unix operating system.
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It is derived from language BCPL
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Language Categories(Paradigms): Imperative Procedural
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C evolved a type structure; created on a tiny machine
as a tool to improve a meager programming
environment.
C has become one of the dominant languages of today.
BACKGROUND
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C developed in 1972 by Dennis Ritchie at the Bell
Telephone Laboratories for use with the Unix
OS.
C came into being in the years 1969-1973 and the
most creative period occurred during 1972.
Another spate of changes peaked between 1977
and 1979, when portability of the Unix system
was being demonstrated.
BACKGROUND
Finally, in the middle 1980s, the language was
officially standardized by the ANSI X3J11
committee, which made further changes.
 Until the early 1980s, although compilers existed
for a variety of machine architectures and
operating systems, the language was almost
exclusively associated with Unix; more recently,
its use has spread much more widely, and today
it is among the languages most commonly used
throughout the computer industry.

GOALS &PURPOSE
 What
were the goals and purpose of this
language?
 The original purpose for C was for
systems programming.
 The 'C' programming language was
originally developed for and implemented
on the UNIX operating system, on a DEC
PDP-11 by Dennis Ritchie.
MAIN FEATURES
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C is "simple" in that the number of components in the
language is small-- If two language features
accomplish more-or-less the same thing, C will
include only one.
C's syntax is terse and the language does not restrict
what is "allowed" -- the programmer can pretty much
do whatever they want.
C's type system and error checks exist only at
compile-time.
The compiled code runs in a stripped down run-time
model with no safety checks for bad type casts, bad
array indices, or bad pointers.
There is no garbage collector to manage memory.
Instead the programmer manages heap memory
manually. All this makes C fast but fragile.
FEATURE
DECLARATION

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All of the C programming language’s integer types—char,
short, int, long, long long and pointers or arrays.
There of can be declared as ranged. The valid range for a
given integer type is the implementation defined minimum
and maximum for that type. Range-min must not be
arithmetically greater than range-max for any ranged
integer.
A ranged integer may be declared with any of the C
programming language storage class identifiers type def,
extern, static, auto, or register.
However, only ranged integers with the auto storage class
can be declared as dynamic ranged integers.
C LANGUAGE MAKE TO THE
FIELD OF COMPUTER LANGUAGES
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The success of Unix was the most important factor; it made the
language available to hundreds of thousands of people.
Unix's use of C and its consequent portability to a wide variety of
machines was important in the system's success. But the language's
invasion of other environments suggests more fundamental merits.
Despite some aspects mysterious to the beginner and occasionally
even to the adept, C remains a simple and small language,
translatable with simple and small compilers.
Its types and operations are well-grounded in those provided by real
machines, and for people used to how computers work, learning the
idioms for generating time and space efficient programs is not
difficult.
At the same time the language is sufficiently abstracted from
machine details that program portability can be achieved.
C LANGUAGE MAKE TO THE
FIELD OF COMPUTER LANGUAGES
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Equally important, C and its central library support always
remained in touch with a real environment. It was not designed in
isolation to prove a point, or to serve as an example, but as a tool
to write programs that did useful things; it was always meant to
interact with a larger operating system, and was regarded as a
tool to build larger tools.
Finally, despite the changes that it has undergone since its first
published description, which was admittedly informal and
incomplete, the actual C language as seen by millions of users
using many different compilers has remained remarkably stable
and unified compared to those of similarly widespread currency,
for example Pascal and Fortran.
There are differing dialects of C—most noticeably, those described
by the older K&R and the newer Standard C—but on the whole, C
has remained freer of proprietary extensions than other
languages. Perhaps the most significant extensions are the `far'
and `near' pointer qualifications intended to deal with
peculiarities of some Intel processors.
C LANGUAGE MAKE TO THE
FIELD OF COMPUTER LANGUAGES
 Although C was not originally designed with portability as a
prime goal, it succeeded in expressing programs, even including
operating systems, on machines ranging from the smallest
personal computers through the mightiest supercomputers.

C is quirky, flawed, and an enormous success. While accidents of
history surely helped, it evidently satisfied a need for a system
implementation language efficient enough to displace assembly
language, yet sufficiently abstract and fluent to describe
algorithms and interactions in a wide variety of environments.
USED C TODAY
Growth in Usage
 During the 1980s the use of the C language
spread widely, and compilers became available on
nearly every machine architecture and operating
system.
 It became popular as a programming tool for
personal computers, both for manufacturers of
commercial software for machines, and for endusers interested in programming.
 At the start of the decade, nearly every compiler
was based on Johnson's pcc; by 1985 there were
many independently-produced compiler products.

USED C TODAY
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C is in many ways the most important of the
hundreds of programming languages that have
been developed in the world to date.
It is by far the most frequently used language for
writing system software, (i.e., operating systems,
other programming languages and compilers),
and it is also widely employed for writing
application programs. C remains particularly
popular in the world of Unix-like operating
systems, and, for example, most of the Linux
kernel (i.e., the core of the operating system) is
written in C. Moreover, it is one of the most
frequently studied languages in computer science
classes.
EXAMPLE

sample program segments
 how to perform some numerical computations.
//Find area of Triangle:
#include < stdio.h>
void main()
{
int area,width,length;
width = 4;
length = 4;
area = 1/2 * width * length;
printf ( "Area of Triangle width %d, length %d
is: %d“,width,length,area );
}
EXAMPLE

sample program segments
 how to input and output different kinds of data, such as
integers, floating pt, and strings.
#include < stdio.h>
void main()
{
int a;
float b;
string c;
scanf("Enter integer %d",&a);
scanf("Enter Floating Point %f",&b);
scanf("Enter String %s",&c);
printf("Integer = %d, Floating Point = %f, String
%s",a,b,c);
}
EXAMPLE

sample program segments
 how to write and invoke a function or procedure.
#include < stdio.h>
void main()
{
doubleprint("C Language");
}
void doubleprint ( string a )// function
{
printf("%s %s",a,a);
}
// the result is C Language C Language
REFERENCES
http://cm.bell-labs.com/cm/cs/who/dmr/chist.html
http://www.mycplus.com/c.asp?ID=1
http://cyberdiem.com/vin/learn.html
http://www.engin.umd.umich.edu/CIS/course.des
/cis400/c/c.html
http://www.coronadoenterprises.com/tutorials/c/c
_intro.htm
http://www.bellevuelinux.org/c.html