The document provides an overview of the C programming language, including its history, characteristics, environment, structure, data types, variables, decision making, looping, libraries, and uses. It describes how C was developed at Bell Labs in the early 1970s and later standardized. The summary highlights C's small fixed set of keywords, static typing, use of headers and functions, and popularity for systems programming and performance-critical applications due to its efficiency and ability to access hardware.

1. C Programming language
Basic Concepts
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2. Index
1. Brief History of C Language
2. About C Programming Language
3. Characteristics of C programming language
4 C Programming Environment
5. Installing C in Windows
6. C Program Structure
7. C Program Structure – Explained
8. C programming – Syntax
9. C Character Set
10 . Keywords
11. Operators in C
12. Operators in C ( continue…..)

3. Index
13. Data Types in C
14. Data Types in C
15. Data Types in C
16. Variables
17. Rules for Variable Declaration
18. Variables Scope
19. Input and Output
20 . Decision Making
21. Looping
22. Looping
23. C Libraries
24. Uses of C

4. Brief History of C Language
The origin of C is closely tied to the development of the UNIX operating
system, originally implemented in assembly language on a PDP-7 by
Ritchie and Thompson. The development of C started in 1972 on the
PDP-11 Unix system and first appeared in Version 2 Unix. In 1978, Brian
Kernighan and Dennis Ritchie published the first edition of The C
Programming Language. This book, known to C programmers as "K&R“.
ANSI –C - In 1990, the ANSI C standard (with formatting changes) was
adopted by the International Organization for Standardization (ISO) as
ISO/IEC 9899:1990, which is sometimes called C90. Therefore, the
terms "C89" and "C90" refer to the same programming language

5. About C Programming language
The C programming language is a structure oriented programming
language, developed at Bell Laboratories in 1972 by Dennis Ritchie
 C programming language features were derived from an earlier
language called “B” (Basic Combined Programming Language –
BCPL)
 C language was invented for implementing UNIX operating system
 In 1978, Dennis Ritchie and Brian Kernighan published the first
edition “The C Programming Language” and commonly known as
K&R C
 In 1983, the American National Standards Institute (ANSI)
established a committee to provide a modern, comprehensive
definition of C. The resulting definition, the ANSI standard
or “ANSI C”, was completed late 1988.

6. Characteristics of C programming language
 There is a small, fixed number of keywords, including a full set o flow of
control and primitive .
 There are a large number of arithmetical and logical operators, such as +,
+=, ++, &, ~, etc.
 Typing is static but weakly enforced all data has a type, but implicit
conversions can be performed; for instance, characters can be used as
integers.
 Strings are not a separate data type, but are conventionally implemented
As null terminated array of characters
 Enumerated are possible with the enum keyword. They are not tagged,
and are freely interconvertible with integers.

7. C programming Environment
The C programming environment consists of -
(1) Text Editor - Programs are typed in Text Editor . By default a new file
Noname.c is opened. Type your programs here , save it , compile and
run.
(2) Compiler – Compiler is a System software that is installed on computer
to compile and run programs. Most widely Turbo C compiler is used

8. Installing C in Windows
To install C in windows first download Turbo C compiler.
.
1. unzip the downloaded file. And run the install.exe file
2. Press ‘Enter’ to continue
3. Enter Source drive where C-compiler and editor will be saved.
4. Enter the source path to locate the exe file. Press ‘Enter’ key.
5. using arrow key , scroll down. Select start installation
6. A message is displayed after successful installation.
7. Go to C:TCBIN right click TC icon select create shortcut.

9. C Program Structure
A C program contains the following –
(a) preprocessor commands
(b) main( ) function
( c ) variables
(d) input and output functions
For example :
#include< stdio.h> /* this is comment line */
#include< conio.h>
Void main()
{
printf(“hello”);
getch();
}

10. C Program structure Explained
1. #include - The first two lines are preprocessor commands that tell the
compiler that the program is using functions in it.
2. Void main() - This is the main function. Program execution begins with the
this function only.
3. Variables - variables hold input and output values.
4. printf() - this is function to give output on the screen. The word “hello” is
displayed on output screen.
5. The getch() – It is a function that ends program and returns to program
window.

11. C Programming - Syntax for writing programs
1. C language is case sensitive language. Hello and hello are two different
words.
2. Programs are written in small caps only ie.. In small letters .Capital words
are treated differently.
3. Inside the main() function , each statement is terminated with semicolon.
4. Comments are used for explanation. /* ….. */ format is used to give
comments in program. They are not executed.

12. C Character Set
The basic C source character set includes the following characters
• Lowercase and uppercase letters: a–z , A–Z
• Decimal digits: 0–9
• Graphic characters: ! " # % & ' ( ) * + , - . / : ; < = > ? [ ] ^ _ { | } ~
• Whitespace characters – space , horizontal tab, vertical tab
new line , form feed

13. Keywords

14. Operators in C
C supports a rich set of operators, which are symbols used within an
expression to specify the manipulations to be performed while evaluating
that expression. C has operators for
1. Arithmetic operators 2. Relational operators
addition + Equals ==
subtraction - Not Equal !=
Multiplication * Greater than >
Division / Greater than equal to >=
Modulus % Less than <
Less than equal to <=

15. Operators in C
3 . Logical operators
logical AND && 8. function call ( )
logical OR || 9. object size sizeof( )
logical NOT !
10. Bitwise
4. increment ++ left shift <<
decrement -- right shift >>
5. Assignment operator =
6. Member selection . ->

16. Data Types in C
1. Basic data types
Data Type Format Specified Space occupied
char %c 1 byte
signed char %c 1 byte
int %d 2 bytes
signed short int %hi 2 bytes
long int %ld 4 bytes
float %f 4 bytes
double %lf 8 bytes
long double %Lf 10 bytes

17. Data Types in C
2. Derived data types -
The derived data types are
(i) Pointer
(ii) Array
(iii) Structure
(iv) Union
(v) Function

18. Data Types in C
3. User defined data types -
Typedef is used to create user defined data type in C
for example structures are declared with typedef to
create linked list data structures in C .
For Example :
typedef struct node
{
int n;
node * p;
}

19. Variables
Variables in C is valid name in the memory where input given by user is
stored and the result of program is stored. When a variable is declared
in program , it occupies space in memory according to its size. Such as
integer type takes 2 bytes of memory, char type takes 1 byte of memory
Example:
int sum;
float average;
char ch;
Here int ,float , char are basic data types.
And Sum , average and ch are variables.
.

20. Rules for declaring variables
1. A variable name should start with letter.
2. It should not be a keyword
3. It can contains underscore character.
4. It should not contain white spaces and special characters.
Example:
sum - valid
1sum - invalid
emp_id - valid
emp id - invalid

21. Variables scope
In C language variables have the following scopes
1. Local Scope - Variable declared inside main() , and variable declared
inside a function has local scope that is it is recognized inside it
local variable can be used inside that block of code.
2. Global Scope - variables declared outside the main() function are
global variable. They are recognized throughout the program.
They can be used by any function .

22. Input and output
C has functions predefined for taking user input in a program and giving output
in the screen
scanf( ) - the scanf() function takes variable number of arguments from user
in predefined format
format - scanf(“%d%c%f”, &a, &b, &c);
printf() - the printf() function gives output of program on the output screen
format - printf(“%d%c%f ” , a , b , c );

23. Decision making
Decision making requires that the programmer specify one or more
conditions to be evaluated or tested by the program, along with a statement
or statements to be executed if the condition is determined to be true, and
other statements to be executed if the condition is determined to be false
Statements used are -
1. simple if
2. if – else
3. if-else ladder
4. nested if – else
5. conditional operator

24. Decision making
Examples :
1. simple if
if( condition1)
{ statements; }
if(condition 2)
{statements ; }
2. if – else
if(condition true)
{ statements; }
else
{ condition false}

25. Looping
There may be a situation, when you need to execute a block of code several
number of times. In general, statements are executed sequentially: The first
statement in a function is executed first, followed by the second, and so on.
Statements inside the loop are executed till condition is true or condition gets
False. There are three types of loops in C
1. For Loop
2. While Loop
3. Do -While Loop

26. Looping
Examples :
1. For Loop
for(initialization ; condition; increm / decrem)
{ statements; }
2. While Loop
while(condition)
{ statements ;
}
3. Do -While Loop
do
{ statements
} while( condition );

27. C Libraries
C language contains set of files header files called library. These header files
Have ‘.h’ extension. They contain functions for various types of operations
Performed in a program. To use them we have to include them in a program
Through include statement. Some of C Library header files are –
stdio.h
conio.h
stdlib.h
graphics.h

28. Uses of C
C is widely used for "system programming", including implementing operating
systems and embedded system applications, due to a combination of
desirable characteristics such as code portability and efficiency, ability to
access specific hardware addresses, ability to match externally imposed
data access requirements, and low run-time demand on system resources.
C can also be used for website programming using CGI as a "gateway" for
information between the Web application, the server, and the browser Some
reasons for choosing C over interpreted languages are its speed, stability,
and near-universal availability C has also been widely used to implement
end-user applications, but much of that development has shifted to newer,
higher-level languages.