| Introduction to the C Tutorial | |  |  |
C IS USUALLY FIRST
The programming language C was originally developed by Dennis Ritchie
of Bell Laboratories and was designed to run on a PDP-11 with a UNIX operating
system. Although it was originally intended to run under UNIX, there has
been a great interest in running it under the MS-DOS operating system on
the IBM PC and compatibles. It is an excellent language for this environment
because of the simplicity of expression, the compactness of the code, and
the wide range of applicability. Also, due to the simplicity and ease of
writing a C compiler, it is usually the first high level language available
on any new computer, including microcomputers, minicomputers, and mainframes.
C is not the best beginning language because it is somewhat cryptic
in nature. It allows the programmer a wide range of operations from high
level down to a very low level, approaching the level of assembly language.
There seems to be no limit to the flexibility available. One experienced
C programmer made the statement, "You can program anything in C", and the
statement is well supported by my own experience with the language. Along
with the resulting freedom however, you take on a great deal of responsibility
because it is very easy to write a program that destroys itself due to
the silly little errors that a good Pascal compiler will flag and call
a fatal error. In C, you are very much on your own as you will soon find.
I ASSUME YOU KNOW NOTHING ABOUT C
In order to successfully complete this tutorial, you will not need any
prior knowlede of the C programming language. I will begin with the most
basic concepts of C and take you up to the highest level of C programming
including the usually intimidating concepts of pointers, structures, and
dynamic allocation. To fully understand these concepts, it will take a
good bit of time and work on your part because they are not particularly
easy to grasp, but they are very powerful tools. Enough said about that,
you will see their power when we get there, just don't allow yourself to
worry about them yet.
Programming in C is a tremendous asset in those areas where you may
want to use Assembly Language but would rather keep it a "simple to write"
and "easy to maintain" program. It has been said that a program written
in C will pay a premium of a 20 to 50% increase in runtime because no high
level language is as compact or as fast as Assembly Language. However,
the time saved in coding can be tremendous, making it the most desirable
language for many programming chores. In addition, since most programs
spend 90 percent of their operating time in only 10 percent or less of
the code, it is possible to write a program in C, then rewrite a small
portion of the code in Assembly Language and approach the execution speed
of the same program if it were written entirely in Assembly Language.
Even though the C language enjoys a good record when programs are transported
from one implementation to another, there are differences in compilers
that you will find anytime you try to use another compiler. Most of the
differences become apparent when you use nonstandard extensions such as
calls to the DOS BIOS when using MS-DOS, but even these differences can
be minimized by careful choice of programming constructs.
Throughout this tutorial, every attempt will be made to indicate to
you what constructs are available in every C compiler because they are
part of the ANSI-C standard, the accepted standard of C programming.
WHAT IS THE ANSI-C STANDARD?
When it became evident that the C programming language was becoming
a very popular language available on a wide range of computers, a group
of concerned individuals met to propose a standard set of rules for the
use of the C programming language. The group represented all sectors of
the software industry and after many meetings, and many preliminary drafts,
they finally wrote an acceptable standard for the C language. It has been
accepted by the American National Standards Institute (ANSI), and by the
International Standards Organization (ISO). It is not forced upon any group
or user, but since it is so widely accepted, it would be economic suicide
for any compiler writer to refuse to conform to the standard.
YOU MAY NEED A LITTLE HELP
Modern C compilers are very capable systems, but due to the tremendous
versatility of a C compiler, it could be very difficult for you to learn
how to use it effectively. If you are a complete novice to programming,
you will probably find the installation instructions somewhat confusing.
You may be able to find a colleague or friend that is knowledgeable about
computers to aid you in setting up your compiler for initial use.
This tutorial cannot cover all aspects of programming in C, simply because
there is too much to cover, but it will instruct you in all you need for
the majority of your programming in C, and it will introduce essentially
all of the C language. You will receive instruction in all of the programming
constructs in C, but what must be omitted are methods of programming, since
these can only be learned by experience. More importantly, it will teach
you the vocabulary of C so that you can go on to more advanced techniques
using the programming language C. A diligent effort on your part to study
the material presented in this tutorial will result in a solid base of
knowledge of the C programming language. You will then be able to intelligently
read technical articles or other textbooks on C and greatly expand your
knowledge of this modern and very popular programming language.
HOW TO USE THIS TUTORIAL
This tutorial is written in such a way that the student should sit before
his computer and study each example program by displaying it on the monitor
and reading the text which corresponds to that program. Following his study
of each program, he should then compile and execute it and observe the
results of execution with his compiler. This enables the student to gain
experience using his compiler while he is learning the C programming language.
It is strongly recommended that the student study each example program
in the given sequence then write the programs suggested at the end of each
chapter in order to gain experience in writing C programs.
THIS IS WRITTEN PRIMARILY FOR MS-DOS
This tutorial is written primarily for use on an IBM-PC or compatible
computer but can be used with any ANSI standard compiler since it conforms
so closely to the ANSI standard. In fact, a computer is not even required
to study this material since the result of execution of each example program
is given in comments at the end of each program.
RECOMMENDED READING AND REFERENCE MATERIAL
"The C Programming Language - Second Edition", Brian W. Kernigan &
Dennis M. Ritchie, Prentice Hall, 1988
This is the definitive text of the C programming language and is required
reading for every serious C programmer. Although the first edition was
terse and difficult to read, the second edition is easier to read and extremely
useful as both a learning resource and a reference guide.
Any ANSI-C textbook
Each student should posess a copy of a book that includes a definition
of the entire ANSI-C specification and library. Go to a good bookstore
and browse for one.
