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1. Introduction to C
2. Structure of a C program
3. Control Structure
4. Arrays

 C is a programming language developed by Dennis
Ritchie at AT & T’s Bell Laboratories of USA in 1972.
 Reserves a set of 32 keywords & 40 operators.
 Case sensitive Language (all keywords in lower case).
 Structured Programming language(divided into small
modules).
 High level language (Machine independent,
sophisticated programming language that uses
familiar English (or any human language).
 Also known as Middle level language because it is
binding the gap b/w a Machine language & high level
language.

Character Set 32-Keywords
 Alphabets Character
(in Small & Capital
Letters )
 Digits(0-9)
 Special Symbols (e.g.
+, -, *, /, , >, <, @, ; ,
?, _, &, %, #, : , =, {, },
[ , ], etc )
return do enum static goto
continue for short signed auto
register Int break switch struct
unsigned if while extern volatile
double else case sizeof
typedef long float union
default void char const

Constants –
Fixed values which does not change
during the execution of a program.
C Constants
Numeric
Integer Real
Character
Single
String
Backslash
Variables :
Variable is a name give to the area of a
memory to store a particular value which
may change during program execution.
In C variable name consists of a
sequence of alphanumeric
characters(digits , alphabets &
underscore.)
Data Type:
Data type is defined as a finite set of
values along with a set of rules for
permissible operations.
• Primary DT(integer, float, char)
•Pointer DT
•Structured DT(Arrays, Strings, Unions,
Structures)
•User-defined DT
•Void DT
e.g. ‘7’, ‘x’
e.g. ”enter”
e.g. n, t

Operators Expressions
An Operator is a function which is
applied to produce a result.
•Arithmetic Operators - (e.g. +, -,
*, /, % )
• Relational Operators –(e.g. <, >,
<=,>=,==, !=)
•Logical Operators – (e.g. ! , &&, II)
•Assignment Operators- (e.g. a=3;
x=y=z=13; x*=75)
•Special Operators – (e.g. ++, --,
&, etc)
Expression is a combination of
one or more operands with
operators to compute a value.
Example- x+y=c
operator
Operand
or
Variable

Documentation Section
(Common Comment Section)
Pre- Processor Directives Section
(Header Files e.g.- #include<stdio.h>)
Global declaration Section
(Variable that are used in more than one
function in a program e.g. int a,b,c)
main() Function Section
{
Declaration part
Executable Part
}
User Defined Functions Section

/* this is a first program of ‘C’ */ (Comments)
#include <stdio.h>
#include<conio.h> (Pre-Processors or Header files)
int a, b, c; (Global declaration section) (a,b,c variables)
void main() (Main function)
{ (opening bracket denotes start of program)
printf(“enter the value of an”);
printf(“enter the value of bn”);
scanf(“%d”, &a);
scanf(“%d”, &b);
c= a+b;
printf(“sum is %dn”, c);
getch();
} (Closing bracket donates the end of the program)
Printf is a function which is used
to print the strings on the
standard output screen

Control structure is a primary concept in most high-
level programming languages. In its simplest sense, it
is a block of code. More specifically, a control
structure is a container for a series of function calls,
instructions and statements. In changing the order of
statement’s execution there may be three situations:
 Branching
 Looping
 Jumping

Branching statements are also know as decision making
statement. In these statements one group of
statement depending on the result of decisions. The
result may be in the form of two type Expressions in
True or False.
Types of Branching statements:
◦ if statement
◦ if else statement
◦ else if statement
◦ nested if statement
◦ Switch statement

1. if statement :
This is a simple decision making statement which is
used to express the condition in only 1 condition &
1 statement or in simple words if the result is True
then execute else no result is showed.
Syntax: if(expression)
<Statement- Set>

2. if else statement :
It is a two way branching statement. This statement is depends
upon the value of expression is True or False. If the 1st
condition is true then 1st statement execute else 2nd will
execute.
Syntax: if(expression)
{
statement 1
}
else
{
statement 2
}

3. else if statement :
It is a multiple if-else statement. It works with multiple conditions & statements. The output
will be depends upon the true condition.
Syntax: if(expression 1)
{
statement 1
}
else if(expression 2)
{
statement 2
}
else if(expression n)
{
statement n
}
else
{
statement p
}

4. nested if statement :
When if statement appears with in another if
statement it is called nested if statement. Similarly
if else can also be nested.
Syntax: if(expression 1)
if(expression 2)
{
statement 1
}
else
{

statement 2
}
else
if(expression 3)
{
statement 3
}
else
{
statement 4
}

5. switch statement :
It is a multi way decision making statement that chooses one of the
alternatives depending upon the value of the expression. It works as
alternative of else it statement & is more flexible & clear that else if
statement.
Syntax: switch<condition>
{
case 1
statement 1
break;
case 2
statement 2
break;
default:
statement p
}

There are various ways that one may define
as the control structures by using the
different types of loop operations.
Types of looping statements:
◦ for
◦ while
◦ do while

1. for loop :
It is commonly used for repetitive processing. For loop
is suited for the problems where we already know
how many times the body of loop will be executed.
Syntax: for(expression 1; expression 2; expression 3)
<Statement- Set>
Starting
Condition that
to be satisfied
Alternate the
value(++, __)

2. while loop :
While loop is suited for the problems where we are not
certain that how many times the body of loop will
be execute. In this statement condition is evaluated
first & if the condition is true then the body of
the loop will execute.
Syntax: while(expression)
<Statement- Set>

2. do while loop :
Do while loop is suited for the problems where we are not certain
that how many times the body of loop will be executed. More
over condition is tested at the end of the loop.
Syntax: do
{
<Statement- Set>
}
while(expression)

These are those statements that can go to a
particular positions to show the particular
result.
Types of jumping statements:
◦ break
◦ continue
◦ goto

1. break :
The break statement is used to terminate loop or to
exit from switch case structure. The break
statement can be used with a for loop, while loop,
do while loop & switch statement to transfer the
control out of the block.
Syntax: break;

2. continue :
A continue statement can be used with while, do while,
for, & switch statement. Continue statement
transfer the control to the beginning of the loop
after by passing the statement which one not yet
executed.
Syntax: continue;

3. goto :
Statement is used to other of the normal sequence of
program execution by transfer control to one point
to the program with the goto statement.
Syntax: goto Label;

Array is a collection of homogenous (same kind of )data elements
which are stored in a sequential manner in memory location
under a single name. This single name is known as array. In
simple words 1 variable use one data type & store multiple data
elements in it. These multiple or individual elements are known
as subscripted variables. Variable size is always declare with
square brackets. Array is always initialized from 0.
Example – int roll[8];
Types of an Array :
 Single dimensional
 Two dimensional

Single Dimensional Array:
Single Dimensional Array is also known as Linear or a list array.
There is only one subscript is used in this array. It is written
either in row or in column form. It can be used with for loop,
while loop & do while loop.
It may be expressed as:
Storage class Data-type Array-name[size];
storage class defines the
scope (visibility) and life time
of variables and functions in
a program. It may be static,
auto, extern or register

Example :
int roll[8];
In our example, int specifies the data type of array, roll specifies
the name of the array and the value in bracket [8] is specifies that
how many elements (values in any array is called elements) it can
store. This number is called dimension of array.
So, with respect to our example we have declared an array of
integer type and named it “roll” which can store roll numbers of 8
students.

Two Dimensional Array:
Two Dimensional Array is known as non-Linear array. Two
subscripts are used in this array. These two subscripts are used
as row & column form. That’s why it is also known as Row column
array or Square array.
It may be expressed as:
Storage class Data-type Array-name[size1][size2];

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Programming in C Session 1

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Programming in C Session 1