The document provides information about the C programming language. It discusses that C is a procedural language that is case sensitive and can be compiled on various platforms. It also provides examples of C programs, including printing "Hello World", using data types like int and float, and control structures like if-else statements and for loops. The document contains code snippets to demonstrate basic C programming concepts.

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C
www.sunilos.com
www.raystec.com

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C is a Programming Language
It is a primitive programing language.
It is a procedural language.
It is case sensitive.
It can be compiled on variety of platforms.
Used for System Programming.
UNIX, Linux and MySQL database are
written in C.

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Compiled and Run on multiple OS
It can be compiled on variety of platforms.
Compile
Linux
Hello.c
Compile
MacOS
Compile
Windows

4.  An approach to solve a
problem is called program.
 You can take multiple
actions to resolve the
problem. Here Ram will
take action pathD() to
reach to the destination.
 You have to keep some
values/data in your mind to
resolve the problem. Here
some values you have to
keep in mind Ram, Sita,
Lights, and Home.
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What is a Program?

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( What is today’s program? )

6. Program for Computer
 For a computer language, a Program is a set of
instructions to perform a task ( resolve a problem).
 Action taken to perform a task is called function.
 Instructions are called statements. One function may
contain multiple instructions.
 Data/Values used and changed by functions are called
variables.
 A program consists of:
o Functions: perform action
o Variables : remember the data
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7. Hello C – My first program
Program that prints “Hello C” at console:
#include <stdio.h>
/* My first program */
void main() {
o printf("Hello C");
}
Code will be stored in file Hello.c
File extension of a C program must be .c
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8. Program details
stdio.h is a library header file. Included by
preprocessor command #include.
printf is library function that prints passed value
at console.
main() is entry point function. Execution is begin
from this function.
void is a keyword.
/*..*/ is a comment statement that describes
something but does not do anything.
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9. Compile and Execute
 Save program as Hello.c to directory c:myprg
 Open a command prompt and go to c:myprg directory
o cd c:myprg
 Compile program by:
o gcc Hello.c //for Linux
o tcc Hello.c //for Windows
o It will compile and create executable file Hello.exe
 Now execute program by:
o Hello.exe
o Output of this program will be “Hello C”
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Hello.c
(text)
Hello.exe
(machine code)
Compile

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Program
Program Structure
int i = 5 //global variable
void main(){
..
a(5);
}
void a(int k){
int j = 0; //local variable
..
}

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Library
Library
Program 1 Program 2
Program 3 Program 4
 Library is made of multiple reusable programs.

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C Application
ApplicationApplication
Library 1 Library 2
Library 3 Library 4
 Application is made of multiple C programs

13. Variables
 Memory area that stores a
value.
 Values are human
understandable data.
 These values can be
changed by executing a
function.
 Variable is declared and
referred by a name.
 Ex. int i = 5 ;
 Here “i” is variable and
stores value 5.
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5
i
4 Bytes
1010

14. Naming Convention
Name is case sensitive and can be composed of
letters, digits and the underscore character.
Variable name should start with a character or
underscore.
Ex:
o float salary = 1000.10; //correct
o char flag = ‘N’ ; //correct
o int emp_code123 = 101 ; //correct
o int #empCode = 101 ; // Incorrect
o int 9code = 101 ; // Incorrect
o int _code = 101 ; // Correct
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15. Types of Variables
Type Description ( 32 Bit System)
char Typically a single byte contains a character
Ex. char ch = ‘A’ ;
int Contains non-decimal integer number, it occupies 4
bytes
Ex. int i = 5;
float A single-precision floating point value. it occupies 4 bytes
Ex. float f = 5.5;
double A double-precision floating point value. it occupies 8
bytes
Ex. double d = 5.5;
void Represents the absence of type.
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C has following basic data types

16. Basic Data types program
 #include <stdio.h>
 void main() {
 char c = 'A';
 int i = 5;
 float f = 10.5;
 double d = 10.5;

 printf("This is char : %c n", c);
 printf("This is int : %d n", i);
 printf("This is float : %f n", f);
 printf("This is double : %lf n", d);
 }
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OUTPUT
This is char : A
This is int : 5
This is float : 10.500000
This is double : 10.500000

17. Other Data Types
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Data Type
Primitive Derived User Defined
char
int
float
double
void
array
pointer
function
enum
structure
union

18. Data Types
Primitive data types are the basic data types
Derived data types are a derivative of primitive
data types known as arrays, pointer and function.
User defined data types are those data types
which are defined by the user/programmer
himself.
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19. Modifiers
Modifiers are keywords used to increase or
decrease the storage capacity of basic data types.
Modifiers are prefixed with data type.
There are 4 modifiers :
o short: It applies on int and reduces size to 2 bytes.
o long : It applies on int and double data types. It
doubles the size of int (4 to 8 bytes) and double (8 to
16 bytes) data types.
o unsigned: It accepts only +ve value.
o Signed: It accepts both +ve and –ve value.
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20. Modifiers
Example declaration
o short int a = 100;
o long int i = 100;
o long double d = 100.10;
o signed int a = -10; //correct
o signed int a = 10; //correct
o unsigned int b = 10; //correct
o unsigned int b = -10; //incorrect
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21. Size of Data types
 #include <stdio.h>
 void main() {
 printf(“char= %dn", sizeof(char));
 printf("int= %dn", sizeof(int));
 printf("float= %dn", sizeof(float));
 printf("double = %dn", sizeof(double));
 printf("short int= %dn", sizeof(short int));
 printf(“long int = %dn", sizeof(long int));
 printf("long double = %dn", sizeof(long double));
 printf("long long = %dn", sizeof(long long));
 }
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OUTPUT
char= 1
int= 4
float= 4
double = 8
short int= 2
long int= 8
long double = 16
long long = 8

22. Modifiers ( Cont.)
Keyword
Identifier
(Format Specifier) Size ( Bytes) Data Range
char %c 1 -128 to +127
int %d 4 -231
to +231
float %f 4 -3.4e38
to +3.4e38
double %lf 8 -1.7e38
to +1.7e38
long int %ld 8 -263
to +263
unsigned int %u 4 0 to 232
long double %Lf 16 -3.4e38
to +3.4e38
unsigned char %c 1 0 to 255
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23. Signed vs Unsigned
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0 1 00 0 100
1 Byte
0 1 00 0 100
1 Byte
char a = ‘A’;
unsigned char a = ‘A’;
Sign bit
Data bit
Value Range: -27
to +27
Value Range: 0 to 28

24. Constants
Constants refer to fixed values that can not be
changed during program execution.
Constants can be of any of the basic data types.
There are enumeration constants as well.
The const qualifier is used to tell C that the
variable value can not change after initialization.
o Ex.
 const float PI=3.14159;
 OR
 const float PI;
 PI=3.14159;
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25. Literals
These are the fix values assigned to a
variable.
For example
o int i = 5;
o float f = 10.5;
o char c =‘A’ ;
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26. % Format specifier
 Function printf uses “format specifiers” to print formatted
output at console.
 There are many format specifies:
o %i and %d for int
o %c for char
o %f for float
o %s for string
o %e for float or double exponential format
o %o for unsigned octal value
o %x for unsigned hex value
o %p pointer address stored in pointer
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27. Format Specifier Program
 void main() {
 int a = 7;
 float b = 12.345678;
 int c = -10;

 printf("%dn",a);
 printf("%3dn",a); //places leading spaces
 printf("%03dn",a);// places leading zero
 printf("%+dn",a);// always displays sign
 printf("%+dn",c);// always displays sign
 printf("%fn",b);
 printf("%3.2fn",b); //3 digits and 2 decimal
 printf("%sn","Hello");
 printf("%10sn","Hello"); //right justify in length of 10
 printf("%-10sn","Hello"); //left justify in length of 10
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OUTPUT
7
7
007
+7
-10
12.345678
12.35
Hello
Hello
Hello

28. Format Specifier Modifiers
 Modifiers
o can be preceded with specifier to format the value. Its format is:
 flag width.precision
o - flag will be used for left justify
o + flag always displays sign
o 0 flag displays leading zeros
o Width specifies total displayed width
o Precision indicates number of digits after decimals
 Control Codes
o b backspace , f formfeed
o n new line, r carriage return
o t horizontal tab, ' single quote
o 0 null
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29. Input and Output
Input
o Value or Data given to a program is called input.
o It is given from a file or command prompt.
o C has scanf()function to get input from command
prompt.
o Some other library functions are available for data input.
Output
o It means to display data on Screen, Printer or a File.
o Function printf() is frequently used for output data.
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30. Input – scanf()
 It is used to read an input from the command line.
 Following program will read an integer from command line:
 int a; int flag ;
 printf("Enter an integer: ");
 scanf("%d", &a))
 if (a == 0) {
 printf("Error: not an integern");
 } else {
 printf("Read in %dn", a);
 }
 If invalid value is entered then scanf() function will return 0 value.
Here &a denotes memory address of ‘a’ variable.
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31. Control Statement
Branching
o if-else
o switch
Looping
o while
o for
o do-while
o Loop Control
Statements
 break
 continue
 goto
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32. If-else
 #include <stdio.h>
 void main () {
 int rs = 100;
 if (rs > 100) {
 printf("I can buy pizza");
 } else {
 printf("I can not buy pizza");
 }
 }
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While Loop
33

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While Loop
 #include <stdio.h>
 void main() {
o int = 0;
o int round = 0;
o while ( == 0 ) {
 printf( “ !!! n");
 if (++round > 500 ){
• = 1;
 }
o }
 }
34

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For Loop
₹10 for 5 shots
How Much?
Okay!!
35

36.  void main()
 {
o int shot ;
o for (shot=1; shot <= 5; shot++)
o {
o printf("Shot Balloon %d n" , shot);
o }
o }
 }
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For Loop – Five shots
36

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Do-While
#include <stdio.h>
void main () {
o int i = 0 ;
o do {
printf("Hello %d n" , ++i);
o }while (i<5);
}

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Switch statement
 main(){
 int grade = 'A';
 switch( grade )
 {
 case 'A' : printf( "Excellentn" ); break;
 case 'B' : printf( "Goodn" );break;
 case 'C' : printf( "OKn" );break;
 case 'D' : printf( “Improve next time....n" );break;
 default : printf( “Where is your result?n" );break;
 }
 }

39. break statement
It breaks the correct loop or switch
statement
void main () {
int i = 0 ;
while( i == 1) {
printf("Hello %d n" , ++i);
if(i>=5){
break; // breaks the loop
}
};
}
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40. continue statement
It skips 1 iteration of loop
void main () {
int i = 0 ;
while(i < 10) {
++i;
if(i<5){
continue; //Skips this iteration
}
printf("Hello %d n" , i);
};
}
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Add two numbers
 #include <stdio.h>
 void main () {
 int n1 = 5 ;
 int n2 = 10 ;
 int sum ;

 sum = n1 + n2;

 printf("Num 1 %d n" , n1);
 printf("Num 2 %d n" , n2);
 printf("Sum %d n" , sum);
 printf("%d = %d + %d n" , sum, n1, n2);
 }

42. Using functions
 Function is a set of statements that performs a particular
task.
 It is independent and reusable block of code.
 It can be called from other functions.
 It takes number of parameters or no parameters.
 After executing its task it may or may not return a value.
 We already have seen a library function printf()
 Syntax
o returnValue functionName ( dataType param1, dataType param2, .. ) {.. }
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43. Define a function
 void main () {
 int a = 5 ; int b = 10 ;
 int maxValue ;
 maxValue = max(a,b);
 printf(" Max of %d and %d is %dn" , a, b, maxValue);
 }
 int max (int a, int b){
 if (a > b){
 return a;
 }else{
 return b;
 }
 }
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Function
definition
Return
value
Return
value
Function
call
Parameters

44. Arrays
List of same type of elements.
Fix size list.
Elements are accessed by Index
number.
Index number is started by 0.
Made of contiguous memory locations.
Declared as
o dataType arrayName[arraySize];
o int table[10] ; // integer array of size 10
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20
[0]
18
..
10
8
6
4
2
[1]
[8]
[9]
[2]
[3]
[4]
[n]

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One Dimension Array
20
[0]
18
..
10
8
6
4
2
[1]
[8]
[9]
[2]
[3]
[4]
[n]
int table[10];
int a = table[4];
int a = table[2];
printf("%d", table[2]);

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Initialize an Array
20
[0]
18
..
10
8
6
4
2
[1]
[8]
[9]
[2]
[3]
[4]
[n]
int table[10];
table[0] =2;
table[1] =4;
…
Or
int table[] = {2,4,6,8,10,12,14,16,18,20};

47. Print All elements of Array
void main () {
 int table[] = {2,4,6,8,10,12,14,16,18,20};
 int i ;
 for(i=0; i<10;i++){
 printf("Table[%d] : %d n",i, table[i]);
 }
}
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OUTPUT
Table[0] : 2
Table[1] : 4
Table[2] : 6
Table[3] : 8
Table[4] : 10
Table[5] : 12
Table[6] : 14
Table[7] : 16
Table[8] : 18
Table[9] : 20

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Other Data Type Arrays
char chList[5];
chList[0] = ‘A’….
o Or
char[] chList = {‘A’,’B’,’C’,’D’,’E’}
double balance[5] ;
balance[1] = 2.0;
o Or
double balance[5] = {1000.0, 2.0, 3.4, 7.0, 50.0};

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[0]
20
18
..
10
8
6
4
2
[1]
[8]
[9]
[2]
[3]
[4]
[n]
30
27
..
15
12
9
6
3
40
36
..
20
16
12
8
4
90
81
..
45
36
27
18
9
100
90
..
50
40
30
20
10
…
[0] [1] [2] [7] [8]
Multidimensional Arrays – 2D
//Declare array
int table[10][9] ;
//Assign values
table[0][0] =2;
table[1][1] =6;
…

50. M-Array Initialization
 int table[2][3] = {{1,2,3},{4,5,6}}; OR
 int table[][3] = {{1,2,3},{4,5,6}}; OR
 int table[2][3] = {{1,2,3,4,5,6}};
Print all elements of 2D array
 void main () {
 int table[2][3] = {{1,2,3},{4,5,6}};
 int i,j ;
 for(i=0; i<2;i++){
 for(j=0; j<3;j++){
 printf("Table[%d][%d] : %dn", i, j, table[i][j]);
 }
 }
 } www.SunilOS.com 50
OUTPUT
Table[0][0] : 1
Table[0][1] : 2
Table[0][2] : 3
Table[1][0] : 4
Table[1][1] : 5
Table[1][2] : 6

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3D Array
20
[0]
18
..
10
8
6
4
2
[1]
[8]
[9]
[2]
[3]
[4]
[n]
30
27
..
15
12
9
6
3
40
36
..
20
16
12
8
4
90
81
..
45
36
27
18
9
100
90
..
50
40
30
20
10
[0] [1] [2] [8] [9]
20
18
..
10
8
6
4
2
30
27
..
15
12
9
6
3
40
36
..
20
16
12
8
4
20
18
..
10
8
6
4
30
27
..
15
12
9
6
20
18
..
10
8
6
4
2
30
27
..
15
12
9
6
3
40
36
..
20
16
12
8
4
90
81
..
45
36
27
18
9
100
90
..
50
40
30
20
10
90
81
..
45
36
27
18
9
100
90
..
50
40
30
20
10
…
[0]
[1]
[2]

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What’s an operator?
Operators are tokens that trigger some
computation when applied to variables.
Operators can be categorized into:
o Arithmetic operators
o Relational operators
o Logical operators
o Bitwise operators
o Assignment operators
o Misc operators

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Operators
()
++
--
!
~
sizeof
*
/
%
+
-
<<
>>
<
>
<=
>=
==
!=
&
^
|
&&
||
?:
=
op=

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Unary operators
Operator Description Example
() Group expression a = (b+c) * d;
+ Unary plus a = +5;
- Unary Minus a = -5;
~ Bitwise complement a = ~b;
! Logical negation if ( !(a == b){…}
++ Pre or Post increment ++i ; or i++;
-- Pre or Post decrement --i ; or i--;
Used with one operand (value)

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Unary operators
Why value of count variable is different in
pre and post increments?
i = 0;
count = 2 + i++;
i = 0;
count = 2 + i++;
ii
countcount
11
22
i = 0;
count = 2 + ++i;
i = 0;
count = 2 + ++i;
ii
countcount
11
33

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Binary operators
 yyyy
OperandOperand
xxxx
OperandOperand
OperatorOperator

57. Arithmetic binary operators
Operator Description Example
+ Plus a = b + c;
- Minus a = b - c;
* Multiply a = b * c;
/ Division a = b / c;
% Reminder a = b % c;
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void main () {
int a =5;
int b =2;
int r;
r =a%b;
printf("Reminder value : %d n", r);
}
Try

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Assignment binary operators
== AssignmentAssignment
 Assignment is a binary operator.
 The left-hand operand of an assignment must be an
LVALUE.
 An LVALUE is an expression that refers to a region of
memory.
o Names of variables are LVALUES.
o Names of functions and arrays are NOT LVALUES.

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Binary operators
void main () {
int result, val_1, val_2;
result = (val_1 = 1) + (val_2 = 2);
printf("val_1 = %d n",val_1);
printf("val_2 = %d n",val_2);
printf("result = %d n", result);
}
void main () {
int result, val_1, val_2;
result = (val_1 = 1) + (val_2 = 2);
printf("val_1 = %d n",val_1);
printf("val_2 = %d n",val_2);
printf("result = %d n", result);
} val_1 = 1
val_2 = 2
result = 3
val_1 = 1
val_2 = 2
result = 3

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Binary operators
Expressions involving only integers are
evaluated using integer arithmetic.
float result;
int i=25;
int j=10;
result = i/j;
printf("Result %f", result);
float result;
int i=25;
int j=10;
result = i/j;
printf("Result %f", result);
resultresult 2.02.0

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Binary operators
Expressions involving only integers are
evaluated using integer arithmetic.
float result;
int i=25;
int j=10;
result = (float) i/j;
printf("Result %f", result);
float result;
int i=25;
int j=10;
result = (float) i/j;
printf("Result %f", result);
resultresult 2.52.5

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Assignment binary operators
Operator Description Example
+= Assign sum a += a;
-= Assign difference a -= a;
*= Assign product a *= a;
/= Assign quotient a /= a;
%= Assign reminder a %= a;
Compound operators provide a convenient shorthand.
int i;
i = i + 5;
//or
i += 5;
int i;
i = i + 5;
//or
i += 5;

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Relational binary operators
Operator Description Example
< Less than if( a > b ) {..}
> Greater than if( a < b ) {..}
>= Greater than equal to if( a >= b ) {..}
<= Less than equal to if( a <= b ) {..}
== Equal to if( a == b ) {..}
!= Not equal to if( a != b ) {..}
Try above examples with following variable values
int a = 10;
int b = 20

64. Relational binary operators
A ZERO value is considered logical false
and Non-ZERO value is considered true
value in logical operators.
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void main () {
int i= 0; //change to +ve value
if(i){
printf("true %d",i);
}else{
printf("false %d", i);
}
}
Try

65. www.SunilOS.com 65
Logical binary operators
Operator Description Example
&& Logical AND if( a > b && b > c) {..}
|| Logical OR if( a < b || b > c) {..}
! Logical NOT – reverse
the logical state
if ( !( a == b ) ) {..}
Try above examples with following variable values
int a = 10;
int b = 20;
int c = 40;

66. www.SunilOS.com 66
Binary operators
Expressions connected by && and || are
evaluated from left to right.
void main () {
int i=0;
int flag = ((2<3) || (0<i++));
printf("Test: %d n" , flag);
printf("I: %d",i);
}
void main () {
int i=0;
int flag = ((2<3) || (0<i++));
printf("Test: %d n" , flag);
printf("I: %d",i);
} Test: 1
I:0
Test: 1
I:0
This never gets
evaluated!
This never gets
evaluated!

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Bitwise binary operators
Operator Description
<< Shift Left
>> Shift Right
& Bitwise AND
| Bitwise OR
^ Bitwise XOR
~ Unary bitwise complement
It works on bits and perform bit-by-bit operation.

68. Truth Table of Binary Operators
a b a & b a | b a ^ b
0 0 0 0 0
0 1 0 1 1
1 1 1 1 0
1 0 0 1 1
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69. www.SunilOS.com 69
Unary bitwise complement
1 1 11 0 101
~
1 Byte
0 0 00 1 010
int a = 10;
int b = ~a;
www.binaryhexconverter.com/binary-to-decimal-converter

70. www.SunilOS.com 70
Left Shift <<
1 1 01 0 101
<<
1 Byte
1 0 10 0 001
int a = -101;
int b = a<<2;
1
1
Value of b will be -20

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Right Shift >>
1 1 01 0 101
>>
1 Byte
1 0 10 1 100
int a = -101;
int b = a>>2;
1
0
Value of b will be -25

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And bitwise &
0 0 00 1 010
&
1 Byte
0 0 11 1 001
int a = 10;
int b = 60;
int c = a & b;
0 0 00 1 000
Value of c will be 8

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OR bitwise |
1 1 01 0 101
|
1 Byte
0 0 11 1 100
int a = -101;
int b = 57;
int c = a | b;
1 1 11 1 101
Value of c will be 125

74. www.SunilOS.com 74
XOR bitwise ^
1 1 01 0 101
^
1 Byte
0 0 11 1 100
int a = -101;
int b = 57;
int c = a ^ b;
1 1 10 1 011
Value of c will be -94

75. www.SunilOS.com 75
XOR bitwise ^
1 1 01 0 101
^
1 Byte
0 0 11 1 100
byte a = 10;
int b = 20;
int c = a ^ b;
1 1 10 1 001

76. www.SunilOS.com 76
Ternary operators
a?x:ya?x:y
“if a then x else y”
Conditional
result = (x<y) ? x : y;result = (x<y) ? x : y;

77. Miscellaneous Operators
Operator Description Example
sizeof() Returns the size of a
variable.
sizeof(a), where a is integer, will
return 4.
& Returns the address of
a variable.
&a; returns the actual address of
the variable.
* Pointer to a variable. *a;
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void main () {
int a =10;
int *b = &a;
printf("value of c : %d n", a);
printf("value of c : %p n", &a);
printf("value of c : %p n", b);
}
Try

78. www.SunilOS.com 78
Operator Precedence
int a = 2+ 4 + 8;
int a = 2+ 4 * 8;
int a = b = c = 5;

79. Operator Precedence
Category Operator Associativity
Postfix () [] -> . ++ - - Left to right
Unary + - ! ~ ++ - - (type)* & sizeof Right to left
Multiplicative * / % Left to right
Additive + - Left to right
Shift << >> Left to right
Relational < <= > >= Left to right
Equality == != Left to right
Bitwise AND & Left to right
Bitwise XOR ^ Left to right
Bitwise OR | Left to right
Logical AND && Left to right
Logical OR || Left to right
Conditional ?: Right to left
Assignment = += -= *= /= %=>>= <<= &= ^= |= Right to left
Comma , Left to right
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80. www.SunilOS.com 80
Precedence
Operators have the precedence. Higher
precedence operator will be evaluated before the
lower precedence operator.
o int data = a * b + c ;
since * (multiply) has higher precedence than +
(plus) so a & b will be multiplied first then result
will be added to c.
Expression is equivalent to
o int data = (a * b) + c ;

81. Variable Scope
 A scope is a region of the program where a defined
variable can be accessed.
 Outside its scope variable can not be accessed.
 There are 3 places where variable can be defined:
o Inside a function or a block which is called Local
variable. It will be accessible only inside block or
function.
o Outside of all functions which is called Global
variable. It will be accessible in all functions of its
program.
o As function parameter which are called formal
parameter.
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82. Local Variable
Declared inside a function or block.
Accessible to statements inside that
function or block of code.
Can’t be accessed outside function or block.
void main () {
 int a=10; //local variable
 int b=15; //local variable
 printf ("Value of a = %d", a);
}
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83. Global Variable
It is defined outside a function, usually on top of
the program.
It exist in memory throughout the lifetime of your
program.
It can be accessed inside any of the functions
defined for the program.
A program may have global and local variables of
same name but the value of local variable inside a
function will take preference.
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84. Global example
 int g = 20; //global variable
 int gl = 20; //global variable
 void main () {
 int l = 10; //local variable
 int gl = 10; //local variable
 printf ("l = %dn", l);
 printf ("g = %dn", g);
 printf ("gl = %dn", gl);

 printVal();
 }
 int printVal(){
 printf (“Print Val g = %dn", g);
 }
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Try
OUTPUT
l = 10
g = 20
gl = 10
printVal g = 20

85. Initializing Local and Global Vs
It is good programming practice to initialize
variables properly.
Global variables are initialized automatically by the
system at the time of declaration.
Data type int, float, double are initialized by
0, char is initialized by ‘0’ character, and
pointer is initialized by NULL.
Local variables are NOT initialized at the time of
declaration.
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86. Reserved Keywords
auto else long switch
break enum register typedef
case extern return union
char float short unsigned
const for signed void
continue goto sizeof volatile
default if static while
do int struct _Packed
double
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87. Pointers
 It is a variable.
 A pointer variable stores a
memory address of
another variable .
 Memory address can be
accessed by ampersand
(&) operator.
 Here p is a pointer variable
that stores address of a:
o int a = 1;
o int *p = &a;
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88. Pointers ( Cont. )
 #include <stdio.h>
 void main () {
 int a = 10;
 int *p = NULL;
 //store address of ‘a’ in pointer variable
 p = &a ;
 printf("Address of a : %xn", &a );
 printf("Address stored in p : %xn", p );
 printf("Value of *ip variable: %dn", *p );
 }
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0 0 00 1 010
int a = 10;
a= 1110
int *p = &a;
1 011
p= 1100
OUPUT
Address of a : 7903aab4
Address stored in p : 7903aab4
Value of *ip variable: 10

89. Pointers (Cont. )
Pointers must be defined before using them.
Pointer can be of any C data type:
o int *ip ;
o char *cp;
o float *fp;
o double *dp
NULL Pointers
o It is recommended to initialize a pointer by NULL value.
o int *p = NULL;
o If a pointer has NULL value then it is called NULL
pointer.
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90. Passing parameters to Function
There are two ways to pass parameters to a
function:
Pass by Value: C creates a local copy of this
variable. All the changes made on local copy will
not impact original variable.
Pass by Reference: In this case address of the
variable is passed to function. Any changes made
on this address will change the value of original
variable.
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91. Pass by reference example
 void test(int a, int *p){
 a = 20; //Make changes on local copy
 *p = 20; //Make changes on address, will change original variable
 }
 void main () {
 int a = 10; int b = 10;

 //Pass value of ‘a’ and address of ‘b’
 test (a, &b);
 printf(" a = : %dn", a );
 printf(" b = : %dn", b );
 }
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OUTPUT
a = : 10
b = : 20

92. Structure and Union
Both are custom data types defined by
users.
Structures are defined using struct key
word.
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93. Structure
It is user defined data type. That combines basic
data types to make custom data type.
It can combine different type of data types.
Custom Data types can be used as basic data
types.
o struct telephone {
 char *name;
 int number;
o };
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94. www.SunilOS.com 94

95. File Handling and IO
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96. String Handling
 void main(){
o int i,j;
o char name[10], nameCopy[10]; //Define char arrays
o printf(“Enter first String :”);
o scanf(“%s”,name); //Get string from Keyboard
o printf(“n %s”,name); // Print string at console
o i=strlen(name); // Length of String
o printf(“length of name is :%d”,i);
o strcpy(nameCopy,name); //Copy a string
o printf(“n %s”, nameCopy);
}
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97. Recursion ( Cont.)
When a function call itself, called recursion.
o int disp(int x){
o int f ;
o if(x ==1 ){
o f = x ;
o }else{
o f = x * disp(x-1);
o }
o return f;
o }
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98. Recursion
o void main(){
o int a, fact;
o a=5;
o fact = disp(a);
o printf(“Factorial is: %d”,fact);
o getch();
o }...
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99. Math.h
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100. Graphics.h
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101. Disclaimer
This is an educational presentation to enhance the
skill of computer science students.
This presentation is available for free to computer
science students.
Some internet images from different URLs are
used in this presentation to simplify technical
examples and correlate examples with the real
world.
We are grateful to owners of these URLs and
pictures.
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102. Thank You!
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