1. Course: BSC CS
Subject: Programming In C Language
Unit-1
Introduction to C language

2. Function OF Computer
 Input -- Input devices enable us to get information into a computer. Some
examples include a keyboard, mouse, microphone, scanner, or digital camera.
 Storage -- There are two types of storage: temporary and long-term.
RAM, or random access memory, is temporary, meaning it stores information as
you use it, but it is being constantly erased and rewritten as you open and close
files.
Long-term storage holds information for as long as you want it. Hard drives,
portable hard drives, floppy drives, flash drives, CD’s, and DVD’s are long term
storage devices.
 Processor -- A microprocessor controls the computers’ functions. It is smaller
than a dime, but contains millions of transistors that perform millions of
instructions per second. The microprocessor performs these instructions using a
three-step process: fetch, decode and execute.
 Output -- Information that has been processed is communicated back to the
user in the form of words, sounds or pictures, and is delivered through printers,
speakers, monitors or other output devices. Sometimes output is just written
back to a storage dev

3. Basic Building Block Of Computer
Control Unit-
this is the device or a part of computer responsible or
performs such regulating functions..
Arithmetic Logic Unit- this is the part or a circuitry of
the Microprocessor chip for arithmetic operations,
proportional and related functions, and logical
functions.
Memory- this is a part of computer or a card or modules
that inserted to the motherboard’s slot
Input -The System Unit that the system of computer
feeds or decode first the data before to display using the
output devices of computer.
Output Devices- this is refer to the devices of
computer that have an ability to display the information
or can produce a hardcopy of a document.

4. Computer Applications

5. Classification Of Computer

6. Classification Of Programming Language

7. What is UNIX?
 UNIX is an operating system which was first developed in
the 1960s, and has been under constant development ever
since. By operating system, we mean the suite of programs
which make the computer work. It is a stable, multi-user,
multi-tasking system for servers, desktops and laptops.
 UNIX systems also have a graphical user interface (GUI)
similar to Microsoft Windows which provides an easy to
use environment.
 However, knowledge of UNIX is required for operations
which aren't covered by a graphical program, or for when
there is no windows interface available, for example, in a
telnet session.

8. Cont..
 There are many different versions of UNIX, although
they share common similarities. The most popular
varieties of UNIX are Sun Solaris, GNU/Linux, and
MacOS X.

9. What is LINUX?
 It is the software on a computer that enables applications
and the computer operator to access the devices on the
computer to perform desired functions.
 Linux is developed collaboratively, meaning no one
company is solely responsible for its development or
ongoing support. Companies participating in the Linux
economy share research and development costs with
their partners and competitors

10. Windows
 The operating system gives the framework upon which all
other services and applications run. The majority of home
users use a Windows based machine. Most of today’s
applications and games are designed to run solely on
Microsoft systems.
 Microsoft Windows is extremely popular in schools and
colleges, many businesses also use Windows.
 The oldest of all Microsoft’s operating systems is MS-DOS
(Microsoft Disk Operating System). MS-DOS is a text-based
operating system. Users have to type commands rather than
use the more friendly graphical user interfaces
(GUI’s)available today

11. What is algorithm?
 A method that can be used by a computer for the solution
of a problem.
 A sequence of computational steps that transform the
input into the output.
 The word ”algorithm” comes from the name of a Persian
author, Abu Ja’far Mohammed ibn Musa al Khowarizmi (c.
825 A.D.), who wrote a textbook on mathematics.
 An algorithm (pronounced AL-go-rith-um) is a procedure
or formula for solving a problem.

12. Algorithm
Write an algorithm and draw the flowchart for finding
the average of two numbers Algorithm:
 Input: two numbers x and y
 Output: the average of x and y
 Steps:
 input x
 input y
 sum = x + y
 average = sum /2
 output average

13. Introduction to flowcharts
 A flowchart is a graphical representation of an algorithm.

• Start or end of the program

• Computational steps or processing function of a program


• Input or output operation


• Decision making and branching


• Connector or joining of two parts of program

14. Introduction of ‘C’
 Root of the morden language is ALGOL 1960. It’s first computer
language to use a block structure.
 It gave concept of structured programming.
 In 1967, Martin Richards developed a language, BCPL (Basic
Combined Programming Language)

15.  In 1970,by Ken Thompson created a language called as ‘B’.
It used to create early version of Unix.
 In 1972,by Dennis Ritchie introduced new language called as ‘C’ .

16. 1972 Traditional C Dennis Ritchie
1990 ANSI/ISO C ISO Committee
1978 K&R C Kernighan &Ritchie
1989 ANSI C ANSI Committee

17. Features Of C
 It is robust lang whose rich setup of built in functions and operator can be used to write any
complex prog
 Prog written in c are efficient due to severals variety of data types and powerful operators.
 The c complier combines the capabilities of an assembly lang with the feature of high level
language. Therefore it is well suited for writing both system software and business package.
 There r only 32 keywords, severals standard functions r available which can be used for
developing prog.
 c is portable lang , this means that c programes written for one computer system can be run on
another system, with little or no modification.
 c lang is well suited for stuctured programming, this requires user to think of a problems in
terms of function or modules or block. A collection of these modules make a program
debugging and testing easier.
 c language has its ability to extend itself. A c program is basically a collection of functions that are
supported by the c library. We can contuniously add our own functions to the library with the
avaibility of the large number of functions.
 In india and abroad mostly people use c programming lang becoz it is easy to learn and
understand

18. Basic structure of C programming
 To write a C program, we first create functions and then put them together. A C program may contain one
or more sections. They are illustrated below.

 Documentation section
 Link section
 Definition section
 Global declaration section
 main () Function section
 {
 Declaration part
 Executable part


 }
 Subprogram section
 Function 1
 Function 2
 …………..
 …………..
 Function n (User defined functions)

19. Basic structure of ‘C’
Documentation Section
It has set of comment lines(name of program, author details).
What is Comment line??
 To guide a programmer to write a note for function,operation,logic in
between a program.
 Non-executable statement.
 Can’t be nested.
e.g:- /* Hello /* abc */ Hi */
ERROR.

20. Link Section
It provides instructions to the compiler to link function from
the system library.
# include Directive:-
 To access the functions which are stored in the library, it is
necessary to tell the compiler , about the file to be accessed.
Syntax:-
#include<stdio.h>
 stdio.h is header file.

21. Definition Section
 defines all symbolic constants.
 #define instruction defines value to a symbolic constant.
 #define:-
 It is a preprocessor compiler directive, not a statement.
 Therefore it should not end with a semicolon.
 Generally written in uppercase.

22. Global Declaration Section
 Some variables that are used in more than on function,
such variables (global variables) declared in the global
declaration section.
 It also declares all the user-defined function.

23.  Every ‘C’ program must have one main() function section.
 It contains two parts
1) Declaration part:
 It declares all variables used in the executable part.
2) Executable part:
 It has atleast one statement.
Main() function section

24. A simple C program: Printing a line of text
#include <stdio.h>
main()
{
printf(“hello, worldn”);
}
Program output:
hello, world

25. Executing a C program :
Executing a C program involves a series of steps.
They are,
 Creating the program.
 Compiling the program.
 Linking the program with functions that are needed
from the C library.
 Executing the program.

26. How to run a program?
 There are two ways to run programs written in a high-level
language.
 The most common is to Compile the program
 The other method is to pass the program through an interpreter.

27. Compiler
Why compiler is require ?
As machine (a processor) can operate On binary code instruction
only…..If we use higher level language then …For execution of the
program we must Convert it to lower level / machine level
Code.

28. Means,
A program that translates Source code into object code.
The compiler derives its name from the way it works, looking
at the entire piece of source code and collecting and
reorganizing the instructions.

29. Interpreter:
which analyzes and executes each line of source code
without looking at the entire program.
Advantage of interpreter:
It can execute a program immediately.
Compilers require some time before an executable program
emerges.
But,
However, programs produced by compilers Run much faster
than the same programs executed by an interpreter.

30. Compiler
checks for syntax errors if any on success coverts ‘C source
code into object code form which is nearer to machine…

31. process of compiling and running a C program

33. References:
1. Programming in C by yashwant kanitkar
2. ANSI C by E.balagurusamy- TMG publication
3. Computer programming and Utilization by sanjay shah Mahajan Publication
4. .www.cprogramming.com/books.html
5. en.wikipedia.org/wiki/C_(programming_language)
6. www.programmingsimplified.com/c-program-example
7. http://cm.bell-labs.com/cm/cs/who/dmr/chist.html
8. http://en.wikipedia.org/wiki/Comparison_of_programming_languages
9. http://en.wikipedia.org/wiki/List_of_C-based_programming_languages
10. http://en.wikipedia.org/wiki/C_(programming_language)