Unit 1

What is C?

C is a programming language developed at AT & T‟s Bell Laboratories of

USA in 1972. It was designed and written by Dennis Ritche. Dennis
Ritchie is known as the founder of c language.

It was developed to overcome the problems of previous languages such

as B, BCPL etc. Initially, C language was developed to be used in UNIX

operating system.

Features of C
1. Portability or machine independent
2. Sound and versatile language
3. Fast program execution.
4. An extendible language.
5. Tends to be a structured language.

Historical developments of C(Background)

Year Language Developed by Remarks

1960 ALGOL International committee Too general, too abstract

1967 BCPL Martin Richards at Could deal with only specific

Cambridge university problems

1970 B Ken Thompson at AT & Could deal with only specific

T problems

1972 C Dennis Ritche at AT & T Lost generality of BCPL and B

restored
 General Structure of a C program:

/* Documentation section */
/* Link section */
/* Definition section */
/* Global declaration section */ main()
{
Declaration part
Executable part (statements)
}
/* Sub-program section */

➢ The documentation section is used for displaying any information

about the program like the purpose of the program, name of the author, date
and time written etc, and this section should be enclosed within comment
lines. The statements in the documentation section are ignored by the
compiler.
➢ The link section consists of the inclusion of header files.
➢ The definition section consists of macro definitions, defining constants etc,.
➢ Anything declared in the global declaration section is accessible
throughout the program, i.e. accessible to all the functions in the program.
➢ main() function is mandatory for any program and it includes two
parts, the declaration part and the executable part.

➢ The last section, i.e. sub-program section is optional and used when we
require including user defined functions in the program.

First C Program

Before starting the abcd of C language, you need to learn how to write,
compile and run the first c program.

To write the first c program, open the C console and write the following code:

1. //First C Program
2. #include <stdio.h>
3. #include <conio.h>
4. void main()
5. {
6. printf("Hello C Language");
7. getch();
8. }

#include <stdio.h> includes the standard input output library functions.

The printf() function is defined in stdio.h .

#include <conio.h> includes the console input output library functions.

The getch() function is defined in conio.h file.

void main() The main() function is the entry point of every program in c
language. The void keyword specifies that it returns no value.

printf() The printf() function is used to print data on the console.

getch() The getch() function asks for a single character. Until you press
any key, it blocks the screen.

C Character set

The C character set is the fundamental building block for writing C programs. It defines
the valid characters that can be used in source code. The C character set is based on the
ASCII (American Standard Code for Information Interchange) standard and includes the
following categories:

• Alphabetic Characters:
o Uppercase letters: A-Z
o Lowercase letters: a-z

• Digits:
o Numeric characters: 0-9

• Special Characters: These include a wide range of symbols used for various purposes
within a C program. Examples include:
o Arithmetic operators: +, -, *, /, %
o Relational operators: <, >, ==, !=, <=, >=
o Logical operators: &&, ||, !
o Punctuation marks: ;, :, ,, ., ?, !
o Brackets and parentheses: (, ), [, ], {, }
o Quotes: ', "
o Other symbols: &, $, #, _, |, `\`, ~, @, ^

• WhiteSpace Characters: These are non-printing characters used for formatting and
readability, and are typically ignored by the compiler. Examples include:

o Space: ` `
o Horizontal tab: \t
o Vertical tab: \v
o Newline: \n
o Form feed: \f
o Carriage return: \r

Every character in the C character set has a corresponding ASCII value, which is its
numerical representation. This allows characters to be stored and manipulated by the
computer.

C TOKENS:

The smallest individual units are known as tokens. C has six types of tokens.

1: Identifiers
 2: Keywords

3: Constants

4: Strings

5: Special Symbols

6: Operators

Identifiers:

Identifiers refer to the names of variables, constants, functions and arrays. These are
user-defined names is called Identifiers. These identifier are defined against a set of
rules.
Rules for an Identifier
1. An Identifier can only have alphanumeric characters( a-z , A-Z , 0-9 ) and underscore( _
).

2. The first character of an identifier can only contain alphabet( a-z , A-Z ) or underscore ( _
).

3. Identifiers are also case sensitive in C. For example name and Name are two different
identifier in C.

4. Keywords are not allowed to be used as Identifiers.

5. No special characters, such as semicolon, period, whitespaces, slash or comma are

permitted to be used in or as Identifier.

6. C‟ compiler recognizes only the first 31 characters of an identifiers.

E Valid Invalid
x
:
STDNAME Return

SUB $stay

TOT_MARKS 1RECOR
D
_TEMP STD
NAME.
Y2K
Keywords: A keyword is a reserved word. All keywords have fixed meaning that means
we cannot change. Keywords serve as basic building blocks for program statements. All
keywords must be written in lowercase. A list of 32 keywords in c language is given
below:

auto break case char

const continue default do

double enum else extern

float for goto if

int long return register

signed short static sizeof

struct switch typedef union

unsigned void volatile while

Note: Keywords we cannot use it as a variable name, constant name etc.

Data Types/Types:
• To store data the program must reserve space which is done using datatype. A datatype is a
keyword/predefined instruction used for allocating memory for data. A data type specifies the
type of data that a variable can store such as integer, floating, character etc. It used for
declaring/defining variables or functions of different types before to use in a program.
There are 4 types of data types in C language.

Types Data Types

Basic Data Type int, char, float, double

Derived Data Type array, pointer, structure, union

Enumeration Data enum

Type
Void Data Type void

Note: We call Basic or Primary data type.

The basic data types are integer-based and floating-point based. C language supports
both signed and unsigned literals. The memory size of basic data types may change
according to 32 or 64 bit operating system. Let‟s see the basic data types. Its size is given
according to 32 bit architecture.

Size and Ranges of Data Types with Type Qualifiers

Type Size Range Control

(byt String
es)
char or signed char 1 -128 to 127 %c
 unsigned char 1 0 to 255 %c

int or signed 2 -32768 to 32767 %d or %i

int
unsigned int 2 0 to 65535 %u

short int or 1 -128 to 127 %d or %i

signed short
int
unsigned 1 0 to 255 %d or %i
short int
long int or 4 -2147483648 to %ld
signed long 2147483647
int
unsigned 4 0 to 4294967295 %lu
long int
float 4 3.4E-38 to 3.4E+38 %f or %g

double 8 1.7E-308 to %lf

1.7E+308
long double 10 3.4E-4932 to %Lf
1.1E+4932

Variables

A variable is a name of memory location. It is used to store data. Variables are

changeable, we can change value of a variable during execution of a program. . It can be
reused many times.

Note: Variable are nothing but identifiers.

Rules to write variable names:

1. A variable name contains maximum of 30 characters/ Variable name must be upto
8 characters.
2. A variable name includes alphabets and numbers, but it must start with an alphabet.
3. It cannot accept any special characters, blank spaces except under score( _ ).
4. It should not be a reserved word.

Ex : rank1 i MAX mStudent_name

i
n
 Declaration of Variables : A variable can be used to store a value of any data type. The
declaration of variables must be done before they are used in the program. The general
format for declaring a variable.

Syntax : data_type variable-1,variable-2,- , variable-n;

Variables are separated by commas and declaration statement ends with a semicolon.

Ex : int x,y,z;
float a,b; char
m,n;

Assigning values to variables : values can be assigned to variables using the

assignment operator (=). The general format statement is :

Syntax : variable = constant; Ex :

x=100;
a= 12.25;
m=‟f‟;

we can also assign a value to a variable at the time of the variable is declared. The
general format of declaring and assigning value to a variable is :

Syntax : data_type variable = constant;

Ex ; int x=100;
float a=12.25; char m=‟f‟;

Types of Variables in C

There are many types of variables in c:

1. local variable
2. global variable
3. static variable

Constants

Constants refer to fixed values that do not change during the execution of a program.

Note: constants are also called literals.

 C supports several kinds of constants.

CONSTANTS

Numeric Constants Character Constants

Integer Constants Real Constants Single Character Constants String Constants

TYPES OF C CONSTANT:
1. Integer constants
2. Real or Floating point constants
3. Character constants
4. String constants
5. Backslash character constants

Integer constants:

An integer constant is a numeric constant (associated with number) without any

fractional or exponential part. There are three types of integer constants in C
programming:

• decimal constant(base 10)

• octal constant(base 8)
• hexadecimal constant(base 16) For

example:
• Decimal constants: 0, -9, 22 etc
• Octal constants: 021, 077, 033 etc
• Hexadecimal constants: 0x7f, 0x2a, 0x521 etc

• In C programming, octal constant starts with a 0 and hexadecimal constant starts with
a 0x.
 1: Decimal Integer : the rules for represent decimal integer.

a) Decimal Integer value which consist of digits from 0-9.

b) Decimal Integer value with base 10.
c) Decimal Integer should not prefix with 0.
d) It allows only sign (+,-).
e) No special character allowed in this integer.

Ex : valid invalid

7 $77

77 077

+77 7,777

-77

2 : Octal : An integer constants with base 8 is called octal. These rules are :

a) it consist of digits from 0 to 7.

b) It should prefix with 0.
c) It allows sign (+,-).
d) No special character is allowed.

E VALID INVALID
X
:
0123 123 -> it because no prefix
with 0
+0123 0128 -> because digits from 0
to 7.
3 : Hexadecimal : An integer constant with base value 16 is called Hexadecimal.

a) It consist of digits from 0-9,a-f(capital letters & small leters.

Ex : 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
b) it should prefix with 0X or 0x.
c) it allows sign (+,-).
d) No special character is allowed.

EX : OX1a, ox2f

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 Floating point/Real constants:

A floating point constant is a numeric constant that has either a fractional form or an
exponent form. For example:

-2.0

0.0000234

-0.22E-5

Note: E-5 = 10-5

Real Constants : Real constant is base 10 number, which is represented in decimal 0r

scientific/exponential notation.

Real Notation : The real notation is represented by an integer followed by a decimal

point and the fractional(decimal) part. It is possible to omit digits before or after the
decimal point.

Ex : 15.25
.75
30
-9.52
-92
+.94

Scientific/Exponential Notation: The general form of Scientific/Exponential

notation is mantissa e exponent

The mantissa is either a real/floating point number expressed in decimal notation or an

integer and the exponent is an integer number with an optional sign. The character e
separating the mantissa and the exponent can be written in either lowercase or
uppercase.

Ex : 1.5E-
2
100e+3
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 -2.05e2

Character Constant:

Single Character Constant : A character constant is either a single alphabet, a single

digit, a single special symbol enclosed within single inverted commas.

a) it is value represent in „ „ (single quote).

b) The maximam length of a character constant can be 1 character.
EX : VALID INVALID
“a‟ “12”

“A‟ “ab‟
String constant : A string constant is a sequence of characters enclosed in double
quote, the characters may be letters, numbers, special characters and blank space etc

EX : “rama” , “a” , “+123” , “1-/a”

"good" //string constant

"" //null string constant

" " //string constant of six white space

"x" //string constant having single

character. "Earth is round\n" //prints string

with newline Escape characters or backslash

characters:

a) \n newline
b) \r carriage return
c) \t tab
d) \v vertical tab
e) \b backspace
f) \f form feed (page feed)
g) \a alert (beep)
h) \‟ single quote(„)
i) \” double quote(“)
j) \? Question mark (?)
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 k) \\ backslash (\)

Two ways to define constant in C

There are two ways to define constant in C programming.
1. const keyword
2. #define preprocessor

1) C const keyword
The const keyword is used to define constant in C programming.
1. const float PI=3.14;
Now, the value of PI variable can't be changed.
1. #include <stdio.h>
2. #include <conio.h>
3. void main(){
4. const float PI=3.14;
5. clrscr();
6. printf("The value of PI is: %f",PI);
7. getch();
8. }
Output:
The value of PI is: 3.140000

2) C #define preprocessor
The #define preprocessor is also used to define
constant. C#define
The #define preprocessor directive is used to define constant or micro substitution. It
can use any basic data type.
Syntax:
#define token value
Let's see an example of #define to define a constant.
#include <stdio.h>
1. #define PI 3.14
2. main() {
3. printf("%f",PI);
4. }
Output:
3.140000

Formatted and Unformatted Console I/O Functions.

Input / Output (I/O) Functions : In „C‟ language, two types of Input/Output functions
are available, and all input and output operations are carried out through function calls.
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Several functions are available for input / output operations in „C‟. These functions are
collectively known as the standard i/o library.
Input: In any programming language input means to feed some data into program. This
can be given in the form of file or from command line.
Output: In any programming language output means to display some data on screen,
printer or in any file.
The Standard Files
C programming treats all the devices as files. So devices such as the display are
addressed in the same way as files and the following three files are automatically opened
when a program executes to provide access to the keyboard and screen.

Standard File File Pointer Device

Standard stdin Keyboard

input

Standard stdout Screen

output

Standard error stderr Your screen

Input / Output functions are classified into two types

C PROGRAMMING Page 15
 I / O Functions

Formated I/O Functions Unformated I/O Functions

Input Output Input Output

scanf() print() getc() putc()

fscanf() fprintf() getchar() putchar()

gets() puts()

getch()

getche()

.
Formated I/O Functions : formatted I/O functions operates on various types of data.

1 : printf() : output data or result of an operation can be displayed from the computer to
a standard output device using the library function printf(). This function is used to print
any combination of data.

Syntax : printf(“control string “, variable1, variable2, ----- , variablen);

Ex : printf(“%d”,3977); // Output: 3977

printf() statement another syntax :

Syntax : printf(“fomating string”);

Formating string : it prints all the character given in doublequotes (“ “) except formatting
specifier.

Ex : printf(“ hello “);-> hello

printf(“a”); -> a
printf(“%d”, a); -> a value
printf(“%d”); -> no display

scanf() : input data can be entered into the computer using the standard input „C‟
C PROGRAMMING Page 16
 library function called scanf(). This function is used to enter any combination of input.

Syntax : scanf(“control string “,&var1, &var2, ---------- , &varn);

The scanf() function is used to read information from the standard input device

(keyboard). Ex : scanf(“ %d “,&a);-> hello

Each variable name (argument) must be preceeded by an ampersand (&). The (&)
symbol gives the meaning “address of “ the variable.

Unformatted I/O functions:

a) Character I/O
b) String I/O

a) character I/O:

1. getchar(): Used to read a character from the standard input

2. putchar(): Used to display a character to standard output
3. getch() and getche(): these are used to take the any alpha numeric characters
from the standard input
getche() read and display the character
getch() only read the single character but not display
4. putch(): Used to display any alpha numeric characters to standard output

a) String I/O:

1. gets(): Used for accepting any string from the standard input(stdin) eg:gets()

2. puts(): Used to display a string or character array Eg:puts()

3. Cgets():read a string from the console eg; cgets(char *st)
4. Cputs():display the string to the console eg; cputs(char *st)

OPERATORS AND EXPRESSIONS:

Operators : An operator is a Symbol that performs an operation. An operators
acts some variables are called operands to get the desired result.

Ex : a+b;
Where a,b are operands and + is the operator.
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 Types of Operator :
1) Arithmetic Operators.
2) Relational Operators.
3) Logical Operators.
4) Assignment Operators.
5). Unary Operators.
6) Conditional Operators.
7) Special Operators.
8) Bitwise Operators.
9) Shift Operators.

Arithmetic Operators
An arithmetic operator performs mathematical operations such as addition,
subtraction and multiplication on numerical values (constants and variables).
C Program to demonstrate the working of arithmetic
operators #include <stdio.h>
void main()
{
int a = 9,b = 4, c;

c = a+b;
printf("a+b = %d \n",c);

c = a-b;
printf("a-b = %d \n",c);

c = a*b;
printf("a*b = %d \n",c);

c=a/b;
printf("a/b = %d \n",c);

c=a%b;
printf("Remainder when a divided by b = %d \n",c);
}
Output
a+b = 13
a-b = 5
a*b = 36
a/b = 2
Remainder when a divided by b=1

Relational Operators. A relational operator checks the relationship between two

C PROGRAMMING Page 18
operands. If the relation is true, it returns 1; if the relation is false, it returns value 0.
Operands may be variables, constants or expressions.

Relational operators are used in decision making and loops.

Operator Meaning Example Return value

< is less than 2<9 1
< is less than or 2<=2 1
= equal to
> is greater than 2>9 0
> is greater than 3>=2 1
= or equal to
= is equal to 2==3 0
=
! is not equal to 2!=2 0
=

// C Program to demonstrate the working of relational operators

#include <stdio.h>

int main()

int a = 5, b = 5, c = 10;

printf("%d == %d = %d \n", a, b, a == b); // true

printf("%d == %d = %d \n", a, c, a == c); // false

printf("%d > %d = %d \n", a, b, a > b); //false

printf("%d > %d = %d \n", a, c, a > c); //false

printf("%d < %d = %d \n", a, b, a < b); //false

printf("%d < %d = %d \n", a, c, a < c); //true

printf("%d != %d = %d \n", a, b, a != b); //false

C PROGRAMMING Page 19
printf("%d != %d = %d \n", a, c, a != c); //true

printf("%d >= %d = %d \n", a, b, a >= b); //true

printf("%d >= %d = %d \n", a, c, a >= c); //false

printf("%d <= %d = %d \n", a, b, a <= b); //true

printf("%d <= %d = %d \n", a, c, a <= c); //true

return 0;

Output

5 == 5 = 1

5 == 10 = 0

5>5=0

5 > 10 = 0

5<5=0

5 < 10 = 1

5 != 5 = 0

5 != 10 = 1

5 >= 5 = 1

5 >= 10 = 0

5 <= 5 = 1

5 <= 10 = 1
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Logical Operators.

These operators are used to combine the results of two or more conditions. An expression
containing logical operator returns either 0 or 1 depending upon whether expression
results true or false. Logical operators are commonly used in decision making in C
programming.

Operator Meaning Example Return

value
& Logical AND (9>2)&&(17>2) 1
&
| Logical OR (9>2) || (17 = = 7) 1
|
! Logical NOT 29!=29 0

Logical AND : If any one condition false the complete condition becomes false.

Truth Table
Op1 Op2 Op1 && Op2
true true true
true false false
false true false
false false false

Logical OR : If any one condition true the complete condition becomes true.

Truth Table
Op1 Op2 Op1 || Op2
true true true
true false true
false true true
false false false

Logical Not : This operator reverses the value of the expression it operates on i.e, it
makes a true expression false and false expression true.

// C Program to demonstrate the working of logical operators

#include <stdio.h>

int main()
C PROGRAMMING Page 21
{

int a = 5, b = 5, c = 10, result;

result = (a = b) && (c > b);

printf("(a = b) && (c > b) equals to %d \n", result);

result = (a = b) && (c < b);

printf("(a = b) && (c < b) equals to %d \n", result);

result = (a = b) || (c < b);

printf("(a = b) || (c < b) equals to %d \n",

result); result = (a != b) || (c < b);

printf("(a != b) || (c < b) equals to %d \n",

result); result = !(a != b);

printf("!(a == b) equals to %d \n", result);

result = !(a == b);

printf("!(a == b) equals to %d \n", result);

return 0;

Output

(a = b) && (c > b) equals to 1

(a = b) && (c < b) equals to 0

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 (a = b) || (c < b) equals to 1

(a != b) || (c < b) equals to 0

!(a != b) equals to 1

!(a == b) equals to 0

Assignment Operators. Assignment operators are used to assign a value (or) an

expression (or) a value of a variable to another variable.

Syntax : variable name=expression (or) value (or) variable Ex :

x=10;
y=a+b; z=p;

Compound assignment operator:

„C‟ provides compound assignment operators to assign a value to variable in order to

assign a new value to a variable after performing a specified operation.

Operator Meaning
+= x=x+y
-= x=x-y
*= x=x*y
/= x=x/y
%= X=x%y

// C Program to demonstrate the working of assignment operators

#include <stdio.h>

int main()

int a = 5, c; c
C PROGRAMMING Page 23
= a;

printf("c = %d \n", c);

c += a; // c = c+a

printf("c = %d \n", c);

c -= a; // c = c-a

printf("c = %d \n", c);

c *= a; // c = c*a

printf("c = %d \n", c);

c /= a; // c = c/a

printf("c = %d \n", c);

c %= a; // c = c%a

printf("c = %d \n", c);

return 0;

Output

c=5

c = 10

c=5

c = 25

C PROGRAMMING Page 24
 c=5

c=0

Increment and Decrement Operators /Unary Operators:

Unary operators are having higher priority than the other operators. Unary operators, meaning
they only operate on a single operand.

Increment Operator in C Programming

1. Increment operator is used to increment the current value of variable by adding integer 1.

2. Increment operator can be applied to only variables.

3. Increment operator is denoted by ++.

We have two types of increment operator i.e Pre-Increment and Post-Increment

Operator. Pre-Increment

Pre-increment operator is used to increment the value of variable before using in the
expression. In the Pre-Increment value is first incremented and then used inside the
expression.

b = ++y;

In this example suppose the value of variable „y‟ is 5 then value of variable „b‟ will be 6
because the value of „y‟ gets modified before using it in a expression.

Post-Increment

Post-increment operator is used to increment the value of variable as soon as after

executing expression completely in which post increment is used. In the Post-Increment
value is first used in a expression and then incremented.

b = x++;

In this example suppose the value of variable „x‟ is 5 then value of variable „b‟ will be 5
because old value of „x‟ is used.
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 Note :

We cannot use increment operator on the constant values because increment operator
operates on only variables. It increments the value of the variable by 1 and stores the
incremented value back to the variable
b = ++5;

or

b = 5++;

The syntax of the operators is given below.

++<variable name> --<variable name>

<variable name>++ <variable name>--
The operator ++ adds 1 to the operand and – subtracts 1 from the operand. These
operators in two forms : prefix (++x) and postfix(x++).

Operator Meaning
++x Pre increment
- -x Pre decrement
x++ Post increment
x-- Post decrement

Where
1 : ++x : Pre increment, first increment and then do the operation.
2 : - -x : Pre decrement, first decrements and then do the operation.
3 : x++ : Post increment, first do the operation and then increment.
4 : x- - : Post decrement, first do the operation and then decrement.

// C Program to demonstrate the working of increment and decrement

operators #include <stdio.h>
int main()
{
int a = 10, b = 100;
float c = 10.5, d = 100.5;
printf("++a = %d \n",
++a); printf("--b = %d \n",
--b); printf("++c = %f \n",
++c); printf("--d = %f \n",
--d); return 0;
C PROGRAMMING Page 26
 }

Output
++a = 11
--b = 99
++c = 11.500000
++d = 99.500000
Multiple increment operators inside printf

#include<stdio.h>
void main() {
int i = 1;
printf("%d %d %d", i, ++i, i++);
}
Output : 3 3 1

Pictorial representation

Explanation of program

I am sure you will get confused after viewing the above image and output of program.
1. Whenever more than one format specifiers (i.e %d) are directly or indirectly related with
same variable (i,i++,++i) then we need to evaluate each individual expression from right
to left.
2. As shown in the above image evaluation sequence of expressions written inside printf
will be – i++,++i,i
3. After execution we need to replace the output of expression at appropriate place

Step
N Explanation
o
Evaluate
1 At the time of execution we will be using older value of i = 1
i++

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 Evaluate At the time of execution we will be increment value already
2
++i modified after step 1 i.e i = 3

Evaluate
2 i At the time of execution we will be using value of i modified
in step 2

Postfix and Prefix Expression in Same Statement

#include<stdio.h>
#include<conio.h>
void main() {
int i = 0, j = 0; j =
i++ + ++i;
printf("%d\n", i);
printf("%d\n", j);
}

Output :
2
2

Explanation of Program

C PROGRAMMING Page 28
 Conditional Operator/ Ternary operator:
conditional operator checks the condition and executes the statement depending of the
condition. A conditional operator is a ternary operator, that is, it works on 3 operands.
Conditional operator consist of two symbols.

1 : question mark (?).

2 : colon ( : ).

Syntax : condition ? exp1 : exp2;

It first evaluate the condition, if it is true (non-zero) then the

“exp1” is evaluated, if the condition is false (zero) then the “exp2” is evaluated.

#include <stdio.h>
int main(){
char February;
int days;
printf("If this year is leap year, enter 1. If not enter any integer: ");
scanf("%c",&February);
// If test condition (February == 'l') is true, days equal to 29.
// If test condition (February =='l') is false, days equal to
28. days = (February == '1') ? 29 : 28;
printf("Number of days in February =
%d",days); return 0;
}

Output
If this year is leap year, enter 1. If not enter any integer: 1
Number of days in February = 29

Bitwise Operators:
Bitwise operators are used to manipulate the data at bit level. It operates on integers
only. It may not be applied to float.In arithmetic-logic unit (which is within the CPU),
mathematical operations like: addition, subtraction, multiplication and division are done
in bit-level which makes processing faster and saves power. To perform bit-level
operations in C programming, bitwise operators are used.

Operator Meaning
& Bitwise
AND
| Bitwise OR
C PROGRAMMING Page 29
 ^ Bitwise XOR
<< Shift left
>> Shift right
~ One‟s
complement
.

Bitwise AND operator &

The output of bitwise AND is 1 if the corresponding bits of two operands is 1. If either
bit of an operand is 0, the result of corresponding bit is evaluated to 0.
Let us suppose the bitwise AND operation of two integers 12
and 25. 12 = 00001100 (In Binary)
25 = 00011001 (In Binary)
Bit Operation of 12 and 25
00001100
& 00011001

00001000 = 8 (In decimal)

Example #1: Bitwise AND
#include <stdio.h>
int main()
{
int a = 12, b = 25;
printf("Output = %d", a&b);
return 0;
}
Output
Output =8

Bitwise OR operator |

The output of bitwise OR is 1 if at least one corresponding bit of two operands is

1. In C Programming, bitwise OR operator is denoted by |.

12 = 00001100 (In Binary)

25 = 00011001 (In Binary)

Bitwise OR Operation of 12 and 25

00001100
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 | 00011001

00011101 = 29 (In decimal)

Example #2: Bitwise OR

#include <stdio.h>

int main()

int a = 12, b = 25;

printf("Output = %d", a|b);

return 0;

}
Output
Output =29

Bitwise XOR (exclusive OR) operator ^

The result of bitwise XOR operator is 1 if the corresponding bits of two operands are
opposite. It is denoted by ^.

12 = 00001100 (In Binary)

25 = 00011001 (In Binary)

Bitwise XOR Operation of 12 and 25

00001100

| 00011001

00010101 = 21 (In decimal)

Example #3: Bitwise XOR

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#include <stdio.h>

int main()

int a = 12, b = 25;

printf("Output = %d", a^b);

return 0;

}
Output

Output = 21

Bitwise complement operator ~

Bitwise compliment operator is an unary operator (works on only one operand). It

changes 1 to 0 and 0 to 1. It is denoted by ~.

35 = 00100011 (In Binary)

Bitwise complement Operation of 35

~ 00100011

11011100 = 220 (In decimal)

Example #4: Bitwise complement

#include <stdio.h>
int main()

printf("complement = %d\n",~35);

printf("complement = %d\n",~-

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 12); return 0;

Output

Complement = -36

Complement = 11

There are two Bitwise shift operators in C programming:

• Right shift operator

• Left shift operator.

Right Shift Operator

Right shift operator shifts all bits towards right by certain number of specified bits. It is
denoted by >>.

Left Shift Operator

Left shift operator shifts all bits towards left by certain number of specified bits. It is denoted by
<<.

Special Operators

1 ) Comma Operator :The comma operator is used to separate the statement elements
such as variables, constants or expressions, and this operator is used to link the related
expressions together, such expressions can be evaluated from left to right and the value
of right most expressions is the value of combined expressions

Ex : val(a=3, b=9, c=77, a+c)

First signs the value 3 to a, then assigns 9 to b, then assigns 77 to c, and
finaly80(3+77) to value.
2) Sizeof Operator : The sizeof() is a unary operator, that returns the length in bytes o
the specified variable, and it is very useful to find the bytes occupied by the specified
variable in the memory.

Syntax : sizeof(variable-name);

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 int a;
Ex : sizeof(a); //OUTPUT---- 2bytes

Example #6: sizeof Operator

#include <stdio.h>
int main()
{
int a, e[10];
float b;
double c;
char d;
printf("Size of int=%lu bytes\n",sizeof(a));
printf("Size of float=%lu bytes\n",sizeof(b));
printf("Size of double=%lu bytes\n",sizeof(c));
printf("Size of char=%lu byte\n",sizeof(d));
printf("Size of integer type array having 10 elements = %lu bytes\n",
sizeof(e)); return 0;
}
Output

Size of int = 4 bytes

Size of float = 4 bytes
Size of double = 8
bytes Size of char = 1
byte
Size of integer type array having 10 elements = 40 bytes

Expressions

Expressions : An expression is a combination of operators and operands which

reduces to a single value. An operator indicats an operation to be performed on data
that yields a value. An operand is a data item on which an operation is performed.

A simple expression contains only one operator.

Ex : 3+5 is a simple expression which yields a value 8, -a is also a single expression.

A complex expression contain more than one operator.
Ex : complex expression is 6+8*7.

Ex ; Algeberic Expressions C-expression

1 : ax2+bx+c 1: a*x*x+b*x+c
2 : a+bx 2 : a+b*x.
3 : 4ac/b 3 : 4*a*c/b.
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 4 : x2/y2-1 4 : x*x/y*y-1

Operator Precedence : Arithmetic Operators are evaluvated left to right using the
precedence of operator when the expression is written without the paranthesis.They
are two levels of arithmetic operators in C.

1 : High Priority * / %
2 : Low Priority + -.

Arithmetic Expression evaluation is carried out using the two phases from left to right.

1 : First phase : The highest priority operator are evaluated in the 1st phase.
2 : Second Phase : The lowest priority operator are evaluated in the 2nd phase.

Ex : a=x-y/3+z*2+p/4. x=7,
y=9, z=11, p=8. a= 7-
9/3+11*2+8/4.

1st phase :
1 : a = 7-3+11*2+8/4
2 : a = 7-3+22+8/4
3 : a = 7-3+22+2
2nd phase :
1 : a = 4+22+2
2 : a = 26+2
3 : a = 28

The order of evaluation can be changed by putting paranthesis in an expression.

Ex : 9-12/(3+3)*(2-1)

Whenever parentheses are used, the expressions within parantheses highest priority.
If two or more sets of paranthesis appear one after another. The expression contained in
the left-most set is evaluated first and the right-most in the last.
1st phase :
1 : 9-12/6*(2-1)
2 : 9-12/6*1
2nd phase :
1 : 9-2*1
2 : 9-2.
3rd phase :
1 : 7.

Rules for Evaluation of Expression :

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1 : Evaluate the sub-expression from left to right. If parenthesized.
2 : Evaluate the arithemetic Expression from left to right using the rules of precedence.
3 : The highest precedence is given to the expression with in paranthesis.
4 : When parantheses are used, the expressions within parantheses assume highest priority.
5 : Apply the associative rule, if more operators of the same precedence occurs.

Operator Precedence and Associativity :

Every operator has a precedence value. An expression containing more

than one oerator is known as complex expression. Complex expressions are executed
according to precedence of operators.

Associativity specifies the order in which the operators are evaluated with
the same precedence in a complex expression. Associativity is of two ways, i.e left to
ringht and right to left. Left to right associativity evaluates an expression starting
from left and moving towards right. Right to left associativity proceds from right to
left.

The precedence and associativity of various operators in C.

Operat Description Precedence Associativity
or
() Function call 1 L-R (left to right)
[] Square
brackets.
+ Unary plus 2 R-L (right to left)
- Unary minus
++ Increment
-- Decrement Not
! operator
~ Complement
* Pointer operator
& Address operator
sizeof Sizeof operator

* Multiplication 3 L-R (left to

/ Division right)
% Modulo
division
+ Addition 4 L-R (left to
- Subtraction right)

C PROGRAMMING Page 36
 << Left shift 5 L-R (left to
>> Right shift right)
< <= > Relational 6 L-R (left to
>= Operator right)
== Equality 7 L-R (left to
!= Inequality right)
& Bitwise AND 8 L-R (left to
right)
^ Bitwise XOR 9 L-R (left to
right)
| Bitwise OR 10 L-R (left to
right)
&& Logical AND 11 L-R (left to
right)
|| Logical OR 12 L-R (left to
right)
?: Conditional 13 R-L (right to left)
= *= /= Assignment 14 R-L (right to left)
%= += operator
-= &=
^= <<=
>>=
, Comma 15 L-R (left to
operator right)

Type Conversion/Type casting:

Type conversion is used to convert variable from one data type to another data type,
and after type casting complier treats the variable as of new data type.
For example, if you want to store a 'long' value into a simple integer then you can
type cast 'long' to 'int'. You can convert the values from one type to another explicitly
using the cast operator. Type conversions can be implicit which is performed by the
compiler automatically, or it can be specified explicitly through the use of the cast
operator.

Syntax:
(type_name) expression;

Without Type Casting:

1. int f= 9/4;
2. printf("f : %d\n", f );//Output: 2
C PROGRAMMING Page 37
 With Type Casting:

1. float f=(float) 9/4;

2. printf("f : %f\n", f );//Output: 2.250000

Example:

#include

<stdio.h> int

main()

printf( "%c\n", (char)65 );

getchar();

or

Type Casting - C Programming

Type casting refers to changing an variable of one data type into another. The compiler
will automatically change one type of data into another if it makes sense. For instance, if
you assign an integer value to a floating-point variable, the compiler will convert the int
to a float. Casting allows you to make this type conversion explicit, or to force it when it
wouldn‟t normally happen.

Type conversion in c can be classified into the following two types:

1. Implicit Type Conversion

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 When the type conversion is performed automatically by the compiler without
programmers intervention, such type of conversion is known as implicit type conversion
or type promotion.

int x;

for(x=97; x<=122; x++)

printf("%c", x); /*Implicit casting from int to char thanks to %c*/

2. Explicit Type Conversion

The type conversion performed by the programmer by posing the data type of the
expression of specific type is known as explicit type conversion. The explicit type
conversion is also known as type casting.
Type casting in c is done in the following form:

(data_type)expression;

where, data_type is any valid c data type, and expression may be constant,
variable or expression.

For

example,

int x;

for(x=97; x<=122; x++)

printf("%c", (char)x); /*Explicit casting from int to char*/

}
C PROGRAMMING Page 39
The following rules have to be followed while converting the expression from one
type to another to avoid the loss of information:

All integer types to be converted to float. All float types to be converted to double.

All character types to be converted to integer.

Example

Consider the following code:

int x=7, y=5

; float z;

z=x/y; /*Here the value of z is 1*/

If we want to get the exact value of 7/5 then we need explicit casting from int to float:

int x=7, y=5;

float z;

z = (float)x/(float)y; /*Here the value of z is 1.4*/

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