C Programming and Data structure C Programming and Data structures

DataTypes in C
Each variable in C has an associated data type. It
specifies the type of data that the variable can store
like integer, character, floating, double, etc.
Each data type requires different amounts of
memory and has some specific operations which
can be performed over it.
The data type is a collection of data with values
having fixed values, meaning as well as its
characteristics.

The data types in C can be classified
 Primitive Data Types
Primitive data types are the most basic data
types that are used for representing simple
values such as integers, float, characters, etc.
 User Defined Data Types
The user-defined data types are defined by
the user himself.
 Derived Types
The data types that are derived from the
primitive or built-in data types are referred to
as Derived Data Types.

Example
 // Create variables
int N = 5; // Integer (whole number)
float F = 5.99; //Floating point number
char C = 'D'; // Character
// Print variables
printf("%dn", N);
printf("%fn", F);
printf("%cn", C);

CVariables
 A variable in C language is the name associated
with some memory location to store data of
different types.
 There are many types of variables in C depending
on the scope, storage class, lifetime, type of data
they store, etc.
 A variable is the basic building block of a C
program that can be used in expressions as a
substitute in place of the value it stores.

What is a variable in C?
 A variable in C is a memory location with
some name that helps store some form of
data and retrieves it when required.
 The size of the variable depends upon the
data type it stores.

CVariable Syntax
 The syntax to declare a variable in C specifies the name
and the type of the variable.
data_type variable_name = value; //defining single variable
(or)
data_type variable_name1, variable_name2;
// defining multiple variable
Here,
 data_type: Type of data that a variable can store.
 variable_name: Name of the variable given by the user.
 value: value assigned to the variable by the user.

Example
int var; // integer variable
char a; // character variable
float fff; // float variables
int A,B,C; // integer variable
char a,b,c; // character variable
float f1,f2,f3,f4; // float variables

There are 3 aspects of defining a variable
 Variable Declaration
 Variable Definition
 Variable Initialization
1. C Variable Declaration
Variable declaration in C tells the compiler about the existence of the
variable with the given name and data type.
2. C Variable Definition
In the definition of a C variable, the compiler allocates some memory
and some value to it.
A defined variable will contain some random garbage value till it is
not initialized.
 Example
int var;
char var2;
3. C Variable Initialization
Initialization of a variable is the process where the user assigns some
meaningful value to the variable when creating the variable.

Example
int var; // variable definition
var = 10; // assignment
or
int var = 10; // variable declaration and definition

How to use variables in C?
// C program to demonstrate the
// declaration, definition and
// initialization
#include <stdio.h>
int main()
{
// declaration with definition
int defined_var;
printf("Defined_var: %dn", defined_var);
// initialization
defined_var = 12; // declaration + definition + initialization
int ini_var = 25; // declaration + definition + initialization
printf("Value of defined_var after initialization: %dn",defined_var);
printf("Value of ini_var: %d", ini_var);
return 0;
}

Output
Defined_var: 0
Value of defined_var after initialization: 12
Value of ini_var: 25

Rules for NamingVariables in C
You can assign any name to the variable as
long as it follows the following rules:
 A variable name must only contain alphabets,
digits, and underscore.
 A variable name must start with an alphabet or
an underscore only. It cannot start with a digit.
 No white space is allowed within the variable
name.
 A variable name must not be any reserved
word or keyword.
 Total variable size is 31

CVariableTypes
 The C variables can be classified into the
following types:
LocalVariables
GlobalVariables
StaticVariables
AutomaticVariables

1. LocalVariables in C
A Local variable in C is a variable that is declared inside a
function or a block of code. Its scope is limited to the block or
function in which it is declared.
Example of LocalVariable in C
// C program to declare and print local // variable inside a function
#include <stdio.h>
void function()
{
int x = 10; // local variable
printf("%d", x);
} int main()
{
function();
}
Output: 10

2. GlobalVariables in C
 A Global variable in C is a variable that is declared outside the function or a block of
code.
we can access the global variable anywhere in the C program after it is declared.
Example of GlobalVariable in C
 // C program to demonstrate use of global variable #include <stdio.h>
int x = 20; // global variable
void function1()
{
printf("Function 1: %dn", x);
}
void function2()
{
printf("Function 2: %dn", x);
}
int main()
{
function1();
function2();
return0;
} Output: Function 1: 20Function 2: 20

3. StaticVariables in C
 A static variable in C is a variable that is
defined using the static keyword. It can be
defined only once in a C program and its
scope depends upon the region where it is
declared (can be global or local).
 The default value of static variables
is zero.
 Syntax of StaticVariable in C
static data_type variable_name = initial_value;
EXAMPLE
static int y = 30; // static variable

4.AutomaticVariable in C
All the local variables are automatic variables by
default.They are also known as auto
variables. auto keyword to define the auto
variables.
The default value of the auto variables is a garbage
value.
Syntax of AutoVariable in C
 auto data_type variable_name;
or
data_type variable_name; (in local scope)
 auto int y = 20; // automatic variable
Example of autoVariable in C
auto int y = 20; // automatic variable

ConstantVariable in C
 A constant variable in C is a read-only variable whose
value cannot be modified once it is defined. We can
declare a constant variable using the const keyword.
Syntax of ConstVariable in C
const data_type variable_name = value;
Example:
{
const int C = 20;
// changing values
not_C = 40;
C = 22;
}

Comments in C with examples
 What are Comments in C?
Comment is a piece of text which doesn’t have any
impact on the output of the program, it is there for
documentation purposes.
 Comments are completely ignored by the C
compilers.
#include <stdio.h>
int main()
{
// Welcome message to Beginners Book readers
printf("Hi,Welcome to BeginnersBook.com!");
return 0;
}

Types of Comments in C
1. Single line comment – Starts with // and
valid till the end of line
2. Multi-line comment – Starts with /* and
ends with */ , it can have any number of
lines.
// displaying the sum of two numbers
printf("%d",sum);
/* Here we are finding out the square of the
given number "num" by multiplying the
number by itself and storing the result in
another int variable numSquare */

Structure of the C Program
There are 6 basic sections responsible for
the proper execution of a program.
Sections are mentioned below:
Documentation
Preprocessor Section
Definition
Global Declaration
Main() Function
Sub Programs

1. Documentation
 This section consists of the description of the
program, the name of the program, and the
creation date and time of the program. It is
specified at the start of the program in the form of
comments. Documentation can be represented as:
 // description, name of the program, //
programmer name, date, time etc.
or
 /* description, name of the program, programmer
name, date, time etc. */

2. Preprocessor Section
 All the header files of the program will be
declared in the preprocessor section of the
program. Header files help us to access
other’s improved code into our code. A
copy of these multiple files is inserted into
our program before the process of
compilation.
Example:
 #include<stdio.h>
 #include<math.h>

3. Definition
 Preprocessors are the programs that
process our source code before the process
of compilation.
 Preprocessor directives start with the
‘#’ symbol.
 The #define preprocessor is used to create
a constant throughout the program.
 Example:
#define long long ll

4. Global Declaration
 The global declaration section contains
global variables, function declaration, and
static variables. Variables and functions
which are declared in this scope can be
used anywhere in the program.
Example:
int num = 18;

5. Main() Function
 Every C program must have a main function.
The main() function of the program is written in this section.
Operations like
Declaration and execution are performed inside the curly braces of
the main program.
The return type of the main() function can be int as well as void
too.
 void main() tells the compiler that the program will not return
any value.
 int main() tells the compiler that the program will return an
integer value.
 Example:
void main()
(or )
int main()

6. Sub Programs
 User-defined functions are called in this
section of the program. The control of the
program is shifted to the called function
Example:
 int sum (int x, int y)
{
return x+y;
}

// Documentation
/**
* file: sum.c
* author: you
* description: program to find
sum.
*/
// Link
#include <stdio.h>
// Definition
#define X 20
// Global Declaration
int sum(int y);
// Main() Function
int main(void)
{
int y = 55;
printf("Sum: %d", sum(y));
return 0;
}
// Subprogram
int sum(int y)
{
return y + X;
}
Output
Sum: 75

Sections Description
/**
* file: sum.c
* author: you
* description: program to find sum**/
It is the comment section and is part of the description
section of the code.
#include<stdio.h>
Header file which is used for standard input-output. This is
the preprocessor section.
#define X 20
This is the definition section. It allows the use of constant X
in the code.
int sum(int y)
This is the Global declaration section includes the function
declaration that can be used anywhere in the program.
int main()
main() is the first function that is executed in the C program.
{…}
These curly braces mark the beginning and end of the main
function.
printf(“Sum: %d”, sum(y));
printf() function is used to print the sum on the screen.
return 0;
We have used int as the return type so we have to return 0
which states that the given program is free from the error
and it can be exited successfully.
int sum(int y)
{
return y + X;
}
This is the subprogram section. It includes the user-defined
functions that are called in the main() function.

printf() function:
The prinf() function is used to display (or print)
output on the console screen.
Syntax of printf() function:
printf("format string",arguments);
Format string always starts with a ‘%’ character. For
example format string for integer is %d, for string
%s, for float %f and so on.
scanf() function:
The scanf() function is used to read the input entered
by user.
Syntax of scanf() function:
scanf("format string",arguments);

Example
#include<stdio.h>
int main()
{
int num1,num2,sum;
printf("Enter first number: "); //Reading the 1st input no:
scanf("%d",&num1);
printf("Enter second number: "); //Reading the 2nd i/p
scanf("%d",&num2);
//calculating sum of two entered numbers
sum=num1+num2;
//Printing the sum of input numbers using printf()
printf("Sum of : %d “, sum);
return 0;
}
O/P:
Enter first number:50
Enter second number:10
Sum of :60

Example 2: Print the square of
input number
#include<stdio.h>
int main()
{ int num;
printf("Enter a number: ");
scanf("%d",&num);
printf("Square of entered number is: %d ",num*num);
return 0;
}
Output
Enter a number: 7
Square of entered number is:49

1. C Hello World Program
#include <stdio.h>
int main()
{
printf(“Hello,World!n”);
return 0;
}

2. C Program to PrintYour Own
Name
#include <stdio.h>
int main()
{
printf(“Your Namen”);
return 0;
}

3. C Program to Print an Integer Entered By
the User
#include <stdio.h>
int main()
{
int num;
printf(“Enter an integer:“);
scanf(“%d”, &num);
printf(“You entered: %dn”, num);
return 0;
}

4.C Program to Multiply two Floating-Point
Numbers
#include <stdio.h>
int main()
{
float num1, num2, product;
printf(“Enter two floating-point numbers:“);
scanf(“%f %f”, &num1, &num2);
product = num1 * num2;
printf(“Product: %fn”, product);
return 0;
}

5. C Program to SwapTwo Numbers
#include <stdio.h>
int main()
{
int num1, num2, temp;
printf(“Enter two numbers:“);
scanf(“%d %d”, &num1, &num2);
temp = num1;
num1 = num2;
num2 = temp;
printf(“After swapping: num1 = %d, num2 = %dn”, num1,
num2);
return 0;
}

6. C Program to Calculate Fahrenheit to
Celsius
#include <stdio.h>
int main()
{
float fahrenheit, celsius;
printf(“Enter temperature in Fahrenheit:“);
scanf(“%f”, &fahrenheit);
celsius = (fahrenheit – 32) * 5 / 9;
printf(“Temperature in Celsius: %fn”, celsius);
return 0;
}

7.C Program to add two numbers
#include<stdio.h>
#include<conio.h>
int main()
{
int a, b, sum; /*Variables Declaration */
clrscr(); /* Clears the screen */
printf("Enter the value of a: ");
scanf("%d", &a); /* Reading First Number */
printf("Enter the value of b: ");
scanf("%d", &b); /* Reading Second Number */
sum = a + b; /* Finding Sum */
printf("Sum of %d and %d is %d.", a,b,sum);
getch(); /* Holds the output */
return 0;
}

8.C Program to find the area of a circle
/* Program to find the area of a circle */
/* Documentation Section */
# include<stdio.h> /* Preprocessor Section */
# include<conio.h>
# define PI 3.14 /* Definition Section */
void main() /* main( ) function */
{
float area,r; /* Local variable declaration */
clrscr(); // Executable part of the program
printf("n Enter the radius:n");
scanf("%f",&r);
area= PI*(r*r);
printf("n Area of the Circle = %8.2f", area);
getch();
}
Output
Enter the radius: 4.5
Area of the Circle = 63.58

OPERATORS IN C
 Operator: An operator is a symbol that specifies
an operation to be performed on operands.
Eg: x= a+b; where + is an operator.
 Operands: An operand is an entity on which an
operation is to be performed.An operand can be
a variable name, a constant, a function call or a
macro name.
Eg. x= a+b; where x, a, b are the operands.
• Expression: An expression is a sequence of
operands and operators

Arithmetic operators
Assignment operators
Relational operators
Logical operators
Bit wise operators
Conditional operators (ternary operators)
Increment/decrement operators
Special operators.
To study….


The symbols which are used to perform logical and
mathematical operations in a C program are
called C operators.
These C operators join individual constants and
variables to form expressions.
Operators, functions, constants and variables are
combined together to form expressions.
Introduction


Types of Operators Description
Arithmetic Operators
Perform mathematical calculations like addition,
subtraction, multiplication, division and
modulus
Assignment
Operators
Assign the values for the variables in C programs.
Relational operators Compare the value of two variables.
Logical operators Perform logical operations on the given two variables.
Bit wise operators Perform bit operations on given two variables.
Conditional (ternary)
operators
Conditional operators return one value if condition is
true and returns another value is condition is false.
Increment/decrement
operators
Either increase or decrease the value of the variable
by one.
Special operators &, *, sizeof( ) and ternary operators.
Types of C Operators

Arithmetic
Operators/Operation Example
+ (Addition) A+B
– (Subtraction) A-B
* (Multiplication) A*B
/ (Division) A/B
% (Modulus) A%B
ARITHMETIC OPERATORS IN C

#include <stdio.h>
int main()
{
int a=40,b=20, add,sub,mul,div,mod; add = a+b;
sub = a-b;
mul = a*b;
div =a/b;
mod = a%b;
printf("Addition of a, b is : %dn", add);
printf("Subtraction of a, b is : %dn", sub);
printf("Multiplication of a, b is : %dn", mul);
printf("Division of a, b is : %dn", div);
printf("Modulus of a, b is : %dn", mod);
return 0;
}
Example showing use of Arithmetic Operator


Operators Example/Description
=
test = 10;
10 is assigned to variable test
+=
test += 10;
This is same as test = test + 10
-=
test -= 1;
This is same as test = test – 10
*=
test *= 100;
This is same as test = test * 10
/=
test /= 20;
This is same as test = test / 10
%=
test %= 2;
This is same as test = test % 10
&=
test&=10;
This is same as test = test & 10
^=
test ^= 10;
This is same as test = test ^ 10
ASSIGNMENT OPERATORS IN C

# include <stdio.h>
int main()
{
int Total=0,i;
for(i=0;i<10;i++)
{
Total+=i; // This
is same as Total =
Toatal+i
}
printf("Total = %d", Total);
return 0;
}
Example showing use of Assignment
Operator

> x > y (x is greater than y)
< x < y (x is less than y)
>= x >= y (x is greater than or equal to y)
<= x <= y (x is less than or equal to y)
== x == y (x is equal to y)
!= x != y (x is not equal to y)
RELATIONAL OPERATORS IN C
Relational operators are used to find the relation between two
variables. i.e. to compare the values of two variables in a C program.

#include <stdio.h>
int main()
{
int m=40,n=20;
if (m == n)
{
printf("m and n are equal");
}
else
{
printf("m and n are not equal");
}
return 0;
}
Example showing use of
Relational Operator

&&
(logical AND)
(a>5)&&(b<5)
It returns true when both conditions are true
| |
(logical OR )
(a>=10)||(b>=10)
It returns true when at-least one of the
condition is
true
!
(logical NOT)
!((a>5)&&(b<5))
It reverses the state of the operand “((a>5)
&& (b<5))”
If “((a>5) && (b<5))” is true, logical NOT
operator makes it false
LOGICAL OPERATORS IN C

#include <stdio.h>
int main()
{
int m=40,n=20;
int a=20,p=30;
if (m>n && m !=0)
{
printf("&& Operator : Both conditions are truen");
}
if (a>p | | p!=20)
{
printf("| | Operator : Only one condition is truen");
}
if (!(m>n && m !=0))
{
printf("! Operator : Both conditions are truen");
}
else
{
printf("! Operator : Both conditions are true. " "But, status is inverted as falsen");
}
return 0;
}
Example showing use of Logical Operator

These operators are used to perform bit operations.
Decimal values are converted into binary values
which are the sequence of bits and bit wise operators
work on these bits. Following are bitwise operator
1) & Bitwise AND
2) | Bitwise OR
3) ~ Bitwise NOT
4) ^ XOR
5) << Left Shift
6) >> Right Shift
BIT WISE OPERATORS IN C

#include <stdio.h>
int main()
{
int m = 40,n = 80,AND_opr,OR_opr,XOR_opr,NOT_opr ;
AND_opr = (m&n);
OR_opr = (m|n);
NOT_opr = (~m);
XOR_opr = (m^n);
printf("AND_opr value = %dn",AND_opr );
printf("OR_opr value = %dn",OR_opr );
printf("NOT_opr value = %dn",NOT_opr );
printf("XOR_opr value = %dn",XOR_opr );
printf("left_shift value = %dn", m << 1);
printf("right_shift value = %dn", m >> 1);
}
Program showing Bitwise Operator in C

Conditional operators return one value if condition
is true and returns another value is condition is false.
This operator is also called as ternary operator.
Syntax :
Example :
(Condition? true_value: false_value);
(A > 100 ? 0 : 1);
CONDITIONAL OR TERNARY
OPERATORS IN C

#include <stdio.h>
int main()
{
int x=1, y ;
y = ( x ==1 ? 2 : 0 ) ;
printf("x value is %dn", x);
printf("y value is %d", y); return 0;
}
Program for use of Ternary Operator

Increment operators are used to increase the
value of the variable by one and decrement
operators are used to decrease the value of
the variable by one in C programs.
Increment operator
++var_name; (or) var_name++;
Decrement operator
- -var_name; (or) var_name – -;
Increment / Decrement
Operators

#include <stdio.h>
int main()
{
int i=1;
while(i<10)
{
printf("%d ",i); i++;
}
return 0;
}
Example for increment operators

#include <stdio.h>
int main()
{
int i=1;
while(i<10)
{
printf("%d ",i); i--;
}
return 0;
}
Example for Decrement operators

Special Operators
Comma Operator
Comma operators are used to link
related expressions together.
For example:
int a, c = 5, 10;
The sizeof operator
The sizeof is a unary operator that
returns the size of data (constants,
variables, array, structure, etc).

Example : sizeof Operator
#include <stdio.h>
int main()
{
int a;
float b;
double c;
char d;
printf("Size of int=%lu bytesn",sizeof(a));
printf("Size of float=%lu bytesn",sizeof(b));
printf("Size of double=%lu bytesn",sizeof(c));
printf("Size of char=%lu byten",sizeof(d));
return 0;
}
Output
Size of int = 4 bytes
Size of float = 4 bytes
Size of double = 8 bytes
Size of char = 1 byte

Types of Operators
Arithmetic Operators
Relational Operators
Logical Operators
Assignment Operators
Increment and Decrement Operators
Conditional Operators (Ternary Operators)
Bitwise Operators
Special Operators

Expressions and statements
 An expression represents a single data item-usually a number.
 The expression may consist of a single entity, such as a
constant or variable, or it may consist of some combination of
such entities, interconnected by one or more operators.
 Expressions can also represent logical conditions which are
either true or false.
Several simple expressions are given below:
C=a + b
x = y
t = (u + v)-(2+5)+(20/5)
x <= y ++j
Y=2x2
+5x+10 (Y=2*x^2+5*x+10)

Examples of Simple Expressions
 x = ( y + 3 ); /* x is assigned the value of y + 3 */
 x++; /* x is incremented */
 x = y = 0; /* Both x and y are initialized to 0 */
 proc( arg1, arg2 ); /* Function call returning void */
 y = z = ( f( x ) + 3 ); /* A function-call expression */

C Programming and Data structure C Programming and Data structures

More Related Content

Similar to C Programming and Data structure C Programming and Data structures

Recently uploaded

C Programming and Data structure C Programming and Data structures