Introduction to c programming

CONTENTS
 What is C?
 History
 Why we use c
 Basics of C environment
 Getting started with C
 Data types / Keywords
 Variables / C character set
 Operators
 The If – else statement
 Switch variables
 Loops

What is c ?
o Programming Language written by Brian Kernighan and D
D Dennis Ritchie .
o C has been designed to have both high level languages and
l low level languages so it is often called middle level
languages.
o Highly structured language .
o Handle bit level operation .
o There are zillions of lines of C legacy code .
o It is also used in application program .
o To develop system software- compilers , operating system.

Year Language Developed by Remarks
1960 ALGOL International
Committee
Too general, too
abstract
1963 CPL Cambridge
University
Hard to learn ,
difficult to
implement
1967 BCPL Martin Richards
at Cambridge
University
Could deal with
only specific
problems
1970 B Ken Thompson
at AT & T
Could deal with
only specific
problems
1972 C Dennis Ritchie
at AT & T
Lost generality of
BCPL and B
restored
History

Why we use c ?
Mainly because it produces codes that runs nearly as fast as
code written in assembly language some examples of the use of
c might be :
 Operating systems
 Language compilers
 Assemblers
 Text editors
 Print spoolers
 Network drivers
 Modern programs
 Data bases
 Language interpreters
 Utilities.

Basics of C environment
C system consist of 3 parts
- Environment
- Language
- c standard library.
Development environment has 6 phases .
• Edit : Writing the source code by using some IDE or editor.
• Pre-processor : Already available routine.
• Compile : Translates or converts source to object code for a
s specific platform i.e., source code -> object codes.
• Link : Links object code with libraries and stores on disk.
• Load : Puts the program in memory.
• Execute : Runs the program.

Executing a c program .
Computer Edit program
source code
Compile
Object code
Library files Link object code executable Computer

Getting started c program.
#include<stdio.h> // preprocessor directive .
#include<conio.h>
void main() // Main function.
{ //Start of the program.
printf(“hello world”); // Function from C library that
getch(); is used to print strings to the
clrscr(); output of our screen.
} // End of the program.

Data Types .
1. Integer int 2 bytes
2. Long integer long int 4 bytes
3. Character char 1 bytes
4. Float float 4 bytes
5. Double double 8 bytes
Some Keywords
Auto double Int struct
Break Else Long Switch
Case Enum Register Typedef
Char Extern Return Union
Const Float Short Unsigned
Continue For Signed Void
Default Goto Size of Volatile
do If static While

Variables
 These names of variables consists of numbers , letters ,
and underscores.
 The restriction on names is that you may not use
keywords as the name of variables or functions.
 Declarations are important in multi file programs where a
variables defined in one file must be referred to second
The C Character Set
A character denotes any alphabet , digit or special
symbol used to represent information.
Alphabets A ,B ,……………, Y , Z
A , b ,………….., y , z
Digits 0 , 1 , 2, 3 , 4 , 5 , 6, 7 , 8 , 9
Special symbols ~ ‘ ! @ # % & * ( ) _ - + =
| { } [ ] ; : “ ‘ < > , . ? /

Operators
1. Arithmetic operator
a) Binary operator
+ , - , * , /, %
b) Unary operator
++ , -- , -
++ increment by 1
-- decrement by 1
- negative
2. Assignment operator
int a = 10, b = 5 , c :
c = a+b :
3. Compound Assignment operator
+=, -= , /= , %= , * =
4. Comparison operator
>,< ,>= ,<= , != , ==

5. Logical operator
&& (And) , || (or) , ! (not).
&& (And)
Cond 1 Cond 2 Result
T T T
T F F
F T F
F F F
All condition true the true otherwise false .
|| (or)
Cond 1 Cond 2 Result
T T T
T F T
F T T
F F F
All conditions false result false otherwise true .

! (Not)
Cond 1 Result
T F
F T
• Prefix Increment value than use ++a.
• Postfix Use value than increment a++.
 Write a program to add two numbers.
#include <stdio.h>
#include<conio.h>
void main ()
{
int a=10, b=5;
printf(“a+b=%d”,a+b);
getch();
clrscr();
}

The If – else statement
if (condition) if (condition)
{
Statement 1; statement- sequence 1;
else }
Statement2; else
{
statement - sequence 2;
}

 Write a program to check given no. is even or
odd.
#include <stdio.h>
#include<conio.h>
void main ()
{
int num;
printf(“enter a number”);
scanf(“%d”, & num);
if (num%2 ==0)
printf(“even number”);
else
printf(“odd number”);
getch();
clrscr();
}

Switch variables
{
case value;
case value;
}
 Write a program to show the given character is vowel or constant .
#include<stdio.h>
#include<conio.h>
void main ()
{
char c;
printf(“enter character :”);
scanf(“%c” & c);
switch (c)
{
case ‘a’
case ‘e’
case ‘i’
case ‘o’
case ‘u‘
printf (“vowel”);
break;
default
printf (“const”);
}
getch();
clrscr();
}

Loops
A loop is a sequence of statements which is specified once but
which may be carried out several times in succession.
There are three methods by way of which we can repeat a part of a
program. They are :
a. Using a for statement
b. Using a while statement
c. Using a do- while statement

Write a program to implement for loop.
#include<stdio.h>
#include<conio.h>
Void main();
{
int c;
for (c=1;c<=5;c++);
{
printf(“n%d”,c);
}
getch();
Clrscr();
}
for loop
for (initialization;condition;increament)
{
statement
}

While loop
While (condition)
{
statement;
increment;
}
 Write a program to implement while loop.
#include<stdio.h>
#include<conio.h>
void main()
{
int c =1;
while (c<=5)
{
printf(“n%d”,c);
c++;
}
getch();
clrscr();
}

Do While
do
{
statement;
increment
}
while (condition);
 Write a program to implement do while loop.
#include <stdio.h>
#include<conio.h>
void main()
{
int sum =0, num;
do
{
printf (“enter a number n”)
scanf (“%d”,& num);
sum += num;
}
while (num!=0);
printf (“sum=%d”,sum);
getch();
clrscr();
}

Introduction to c programming

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