1.  What is c?
 Do you tell us about c, perhaps you thing that
is a programming language but……
now……….
 What is z?
 You tell us it is an alphabets. In the same way
c is also an alphabets.
 Now when some one asking you about c
language then tell him about c language.
 This type of answer make an impression on
interviewer, which is beneficial for us.

2.  History of c language –
algol
(kenthomsan) B BCPL (Mortin)
c (Denice Richi)
(At & t bell laboratory in U.S.A.)

3. C language developed in 1972 at & t bell
laboratory in U.S.A.
 First time c language written in Unix, but in
further it written in it self.
 Unix O.S. is also written in c language.

4. Basic element of c languages.
 Every language have some elements which help
us to understand and working with that language.
 So there are some element in c also …..
 Alphabets -
 a, b………?
 A, B………z.
 Numeric values – 0,1,2………9.
 Special symbols –
 # , ; : ( ) [ ] { } / * + - %...............
 Key words –
 There are 32 keywords in c language.

6. Some predefine function in c
 print f ( )
 scan f ( )
 getch ( )
 clrscr ( )
 getche ( )

7.  printf – it is a predefine function which is use
to print something on the screen at runtime.
 printf (“Namaste”);
 In above example what we write down in
double quarts that is printed same an screen.
int x;
x = 10;
printf (“ % d “, x);
In ex printf print the value of x.

8.  scanf – it is also a predefine function
which is use to take user input at runtime
(execution time)
int x;
scanf (“ % d”, f x)
 In above example we take value for x
variable integer type.

9.  getch ( ) – It is also predefine function
which hold the screen, till it dose not get a
character.
 As it get the character it release the
screen.
 getche( ) – getche ( ) is also work same
as getch ( ), but difference it first print the
taken character then release the screen.

10. Inclucle <stdio.h>
vaid maine ( )
{
Print f (“vandematram”);
Getche ( );
Getch ( );
}
 Hear first getche ( ) hold the screen, when he
get a character then it release, then getch()
hold;

11. # include <stdio.h>
void main ( )
{
Print f (“vandematram”);
getch ( );
getche ( );
}
Hear first getch ( ) hold the screen, when
he get a character then it release, then
getche() hold;

12.  Identifiers – Identifiers are such type of entity
through which we uniquely identified any thing.
 ex- variable name, painter name, array name,
function name, structure name, union name etc.
 Rule for identifiers name –
 An identifier contain only alphabets, numeric
values and under score (-).
 An identifiers name always start with alphabets or
under score.
 No special symbols or white space use instead of
under score. (-).

13.  Variable – variable are those identifiers
which value change during the program.
 ex –
int x;
char y;
 Constant – constant are those identifiers
which value never change during in
program.

14.  Data type – it tell us about the type of are
identifiers.
 ex -
int a;
 In above ex- a is an integer type variable, it
hold the integer value the key word int tell
s us.

15.  Type of data type – There are manly two
type of data type in c.
 Primary data type.
 Secondary data type.
Primary data type secondary data type
int string
float array
char painter
double structure
union
function

16.  int– int is a key word which is used to
create a integer type variable.
 ex –
int x
x = 10;
 x hold integer type value.

17.  char – It is also a key word which is used
to create a character type variable it
always hold a single character, which is
denoted by „ ‟ (single a uates)
 char a;
a =„m‟;
 In above a is a character type variable
which hold a single character.

18.  float – it is also a key word which is used
to create a float type variable.
 ex-
 float b;
b = 2.35;
 In above, b is a float type variable hold a
decimal value.

19.  Operators in c-
 C support a number of built-in operators. we have already
used several of them,
 Some are =,+,-,*,&and <.An operator is a symbol that tells the
computer to perform some manipulation to manipulate data
and variables.
 C operators can be classified in to a
 i) number of categories.
 ii) relational operators.
 iii) logical operators.
 iv) assignment operators.
 v) increment & decrement operators
 vi) arithmetic operators
 vii) conditional operators
 viii) bitwise operators
 ix) special operators.

20.  Arithmetic operators-
 C provides all the basic arithmetic operators.
They are listed in table.

Operators Meaning
+ Addition or unary plus
- Subtraction or unary minus
* Multiplication
/ Division
% Modulo division

21.  ex-1.
 int a, b, c;
 b = 10;
 c = 12;
 ex- 2. a + b + c;
float b = 2.5;
c = 3.2;
a = b + c;
 ex-3.
int a;
float b, c;
a = 10;
c = 3.5
b = a + b;

22.  Relation operators-
 We often compare two quantities and
depending on their relation. Take certain
decisions. For this type of comparisons we
use relation operators.
 those are- Operator Meaning
< is less than
<= is less than or equal to
> is greater than
<= is greater than or equal
to
== is equal to

23.  Logical operators-
 In addition to the relational
operators. C has
these following logical operators.
Operator Meaning
&& logical AND
|| logical OR
! logical NOT
 Assignment operators-
 Assignment operators are used to assign an
opropriate value to the variable.
 We use „=‟ as assignment operator.

24.  Increment and decrement operators-
 C allows two very use full operators these
are increment and decrement operators.
 ++ and --
 *The operators ++ adds 1 to the operand,
while – subtracts 1. * both are unary
operators and (such operators which work
with single operand (variable).
 ex- int a;
a + +;

25.  They are implemented in two ways
 Prefix.
 Pastfis.
 Prefix- first perform in crement decrement
then assigne the value.
 int a;
 ++ a;
 int b;
 -- b;
 Postfix – first assigne the the value then
perferm increment decrement.

26.  Conditional operator-
 There is an operator pair “?” is available in C,
to construct conditional expressions of the
form.
 A1 ? A2 : A3
 A1, A2, A3 are expressions .
 in above first expressions A, evaluated.
 a = 10;
 b = 15;
 m = (a > b) ? a : b;
 It is use to replace if use.

27.  Bit wise operators-

28.  If ……. else
 This is a bi-direction conditional control statement. This
statement is used to test a condition and take one of the two
possible actions.
 If the condition is true then a single statement or block is
executed, other wish another single statement or block is
executed.
 if (condition)
 {
 Statement 1
 }
 Else
 {
 Statement 2
 }

29. Nesting of if ……. else-
 We can have another if….. else statement
in the if block or the else block if….. else
statement.

30.  Switch –
 This is a multi-directional conditional control statement some time there is a
need in program to make choice among number of alter natives.
 For making this choice, we use the switch statement.
 switch (expression)
 {
 case 1:
 statement 1;
 Break; ………..
 case 2:
 statement 2;
 … Break; ………
 case 3:
 statement 3;
 …… Break; ……
 default :
 statement 4;
 ………..
 }

31.  Now we will see the same valid invalid ways of writing switch
expression and case expression.
 int a, b, c; char d, e; float f;
 Valid –
 Switch (a) switch (a>b) switch (d+e-3) switch (a>b && b>c)
switch cfine (a,b,)
 Invalid –
 switch (f) switch (a+4.5)
 Valid case 4: case „a‟ : case 2+4
 case „a‟ > „b‟ :
 Invalid –
 case ”second” : case 2.3 : case a :
 case a>b : case a+2 :
 case 2, 3, 4 : case 2 : 4 : 3 :

32.  Loop - loops are used when we want to execute a part of program or a
block of statement several times.
 There are three loop statement in C-
 for loop
 while loop
 do while loop
 for – the for loop is very usefull in C programming.
 It has three expressions and semicolons are used for separating these
expression.
 for (initialization; condition; increment)
 {
 statement;
 }
 ex-
 int a;
 for (a=0; a<3; a++)
 {
 printf (“Namuste”);
 }

33.  While –
 It is written as –
 initialization;
 while (condition)
 {
 statement :
 Increment /Decrement;
 }
 ex- int a;
 a=0;
 while (a<3)
 {
 printf (“ Vande Matram”);
 a ++;
 }

34.  do while – it is different from for and while loop. it first execute the
statement then check the condition.
 initialization :
 do
 {
 statement :
 increment /Decrenet)
 }
 while 9condition);
 ex-
 int a;
 a = 0;
 do
 {
 printf (“ jai Hanuman”);
 a ++;
 }
 while (a < 5);
 * in do while condition is either true or false statement must executed once.

35.  Nested loop-
 When we use a loop inside the another loop body
(both are same) it is known as nested loop.
 ex-
 for (x = 0 ; x < 5 ; x + +)
{
 for (y = 1 ; y < 5 : y + +)
{
 printf (“% d % d ‟‟ x, y) ;
}
}
 In above this the example of nested for loop.

36.  Function – function is an entity which perform
some specific.
 A function is a self-contained subprogram that is
meant to do some specific, well-define task.
 *A program consists of one or more function.
 *If a program has only one function then it must be
the main ( ) function .
 *function always return a value.
 C program have two types of function –
 1. Library function
 2. User define function

37.  Library function –
 C has the facility to provide library functions for
performing some operations. These function are present
in the C library and they are predefined.
Function Name Operation
Sgrt ( ) find squre root of nuber
scanf ( ) take input
printf ( ) for print on screen
strlen ( ) lenth of string
strcmp ( ) comparision
clrscr ( ) for clear the screen
getch ( ) for hold the screen

38.  User- define function-
 User can create their own functions for performing any specific
task of the program. These type of function are called user
define function.
 User define function have these three parts-
 1. Function declaration
 2. Function definition
 3. Function calling
 Function definition-
 The function definition consist of the whole description and
code of a function. It tells what the function is doing and what
are its input and output.
 Function calling-
 A function is called by simply writing its name followed by the
argument list inside the parentheses (if any).

39.  Function declaration-
 Function declaration give the information to calling function
about called function.
 If called function is placed before calling function then there no
need for declaration.
 ex- #includi <stdioh>
 valid ram ( ) ; declaration
 valid main ( ) ; of function
 {
 ram ( ) ; calling offention
 }
 Void ram ( )
 {
 printf (“ vande matram ‟‟) ;
 }

40.  Type of user define function –
 1. function with no argument and no return type.
 2. function with no argument and a return type.
 3. function with argument and no return type.
 4. function with argument and a return type.
 Function with no argument and no return type-
 A function which has no argument and no return type………..
 #include<stdio.h>
 void func ( ) ;
 void main ( )
 {
 func ( ) ;
 }
 void func ( )
 {
 statement ;
 }
 In above program func ( ) has no argument and it does not return any value.

41.  Function with no argument and a return type –
 These type of function do not recene any argument but return
a value.
 int func ( ) ;
 void main ( )
 {
 int n ;
 n = func ( ) ;
 }
 int func ( )
 {
 int a ;
 ………
 ………
 return a ;
 }

42.  function with argument and no return type.-These types of
function have arguments, hence calling function send data to
the calling function but function does not return a value.
 void func (int a) ;
 void main ( )
 {
 int m ;
 func (m);
 }
 void func (int x)
 {
 ……………….
 ……………….
 ……………….
 }

43.  Function with argument and a return type-
 These type function have arguments, so the calling function can send data
to the called function. It can also return any value to the calling function
using return statement.
 int func (int, int)
 {
 void main ( )
 {
 int r ;
 …….
 r = func (a, b) ;
 ……….
 }
 int func (int a, int b)
 {
 ………….
 ………….
 return (expression) ;
 }

44.  Arrays –
 The variables that we have used till now are capable of storing
only one value at a time.
 So we have an array that can hold more than one value of
some type.
 “ Array is a collection of similar type of data.‟‟
 ex -
 int a [10] ;
 a [10] = {1, 2, 5, 3, 2…...} ;
 In above example a is an array of size 10, it can hold 10
values of same time of data type.
 ex-2- int a [3] 0, c‟ ;
 for (c‟ = 0 ; c‟ < 3 ; c‟ ++)
 {
 scanf (“ % d‟‟, & a [c‟] ) ;
 }

45.  ex-1- int a [3] ;
 a [0] = 10 ;
 a [1] = 22 ;
 a [2] = 11 ;
 /* The size of array is 3, it hold three value */
 Print the value of an array –
 int a [3] 0, c‟ ;
 for ( I = 0 ; c‟ < 3 ; c‟ ++ )
{
 printf ( “ % d”, a [i] ) ;

46.  Passing array to a function –
 We know that an array element is treated as any other simple variable in the
program. So we can simply pass an individual array element to the function
as argument.
 void funct ( int a ) ;
 void main ( )
 {
 int arr [10], i ;
 for ( i = 0 ; c‟ < 10 ; c‟ ++ )
 {
 scanf ( “ % d‟‟, & arr [i] ) ;
 funct ( arr [i] ) ;
 }
 void funct ( int num )
 {
 ……………
 ……………
 …………..
 …………..
 }

47.  2- D Array –
 The syntax of 2-d array is similar to 1-d array, but here we
have two subscripts.
 Data type array- name [ row size ] [ Colum size ] ;
 Here row sixe specifies number rows and colum size specifies
number of calumn.
 Reading value in 2-d Array –
 int a [2] [2] 0, c‟, j ;
 for ( c‟ = 0 ; c‟ < 2 ; c‟ ++ )
 {
 for ( j = 0 ; j < 2 ; j ++ )
 {
 scanf ( “ % d‟‟, & a [i] [ j ] ) ;
 }
 }

48.  Displaying values of array –
 int a [2] [2] 0, c‟, j ;
 for (c‟ = 0 ; c‟ < 2 ; c‟ ++ )
{
 for ( j = 0 ; j < 2 ; j ++ )
{
 printf ( “ % d‟‟, a [i] [ j ] ) ;
}
}

49.  Introduction to string –
 In C string are treated as array of char type and are
terminated by a rull character („0‟)
 There are the two forms of initialization of a string variable –
 char str [10] = {„I‟, „n‟ , „d‟ , „I‟ , „a‟ , „10‟ } ;
 char str [10] = “ India „‟ ;
 In second case rull character automatically placed in the end
of string.
 Input of output of string –
 # include < stdio‟h >
 void main ( )
 {
 char str [10] ;
 scanf (“ % s ”, str) ;
 printf (“ % s ‟‟, str) ;
 }

50.  Pointer –
 Pointer is an identier which hold the address
of any variable which data type is similar to
pointer.
 ex-
 int x = 10 ;
 int * p ;
P = & x ;
 In above example p is a pointer which hold
the address of x variable.

51.  Example to understand the painte ?
 # include < stdio.h>
 void main ( )
 {
 int a, * b ;
 a = 10 ;
 b=&a;
 printf (“ % d % d % d % d‟‟ , a, &a, b, * b);
 }
 Output –
 value a - 10
 address of a ………
 address of a ………
 value of a - 10

52.  Pointer to pointer –
 A pointer may be hold the address of
another pointer.
 int *a, **b, c‟ ;
 c‟ = 10 ;
 a = & c‟ ;
b = & a ;
 In above case a hold the address of c‟
variable and double pointer b (**) hold the
address of a.

53.  Increment decrement in pointer –
 Pointer variable also perform increment /
decrement operation ;
 int a, * b ;
a=5;
b=&a;
 b ++ ;
 printf (“ % d ‟‟, b) ;
 In above example pointer increase two by test be
couse increment perform in the address of
variable.
 We can also perform arithmatic operation in
pointer.

54.  Pointer and function –
 The argument to the function can be passed in two ways –
 1. call by value.
 2. call by reference.
 In call by value, only values of argument send to the function.
 But in call by reference address of argument send to the
function.
 Structure –
 Array is a collection of same type of elements, but in real word
application we may need to group different types of logically
related data.
 So for that we use structure.
 “ structure is a collection of different type of corelated data.

55.  Syntax –
 struct tag name
 {
 data type member 1;
 data type member 2;
 ………………..
 ……………..
 data type member x ;
 };
 Here struct is a keyword.
 ex- struct student
 {
 char name [20] ;
 int age ;
 }
 void main ( ) {
 Struct student 51 ;
 51. name = “ arpit ‟‟ ;
 51. age ;
 printf ( “ % s % d ‟‟, 51. name, 51. age) ; }

56.  Union –
 Union is a derived data type like structure, and it can also contain
members of different data types.
 It‟s declaration and accessing of member element is same to
structure only one different in it, use keyword union instead of struct.
 Union union-name
 {
 data type member 1 ;
 data type member 2 ;
 …………………
 };
 main ( )
 }
 Union union-name x ;
 ………………..
 ……………….
 }