Importance Of C

                                                                 C

C is a robust language. means rich set of built in functions and operators  can be used to write any complex program.

Programs written in C are efficent and fast.

There are 32 keywords and several standard functions are available which can be used for developing program.

c is highly portable. this means that c programs written for one computer can be run on another with litte or no modification.

c programing language is structred programming language. means  data can be written in module or function or blocks.

a proper collection of these modules make a complete program.

A simple Program

----------------------------

#include<stdio.h>

main()

{

/* printing begin */

printf(""This is my first program");

}  /* this is main block closed */

Execution of C program

1) Createing the program

2) compiling the program

3) Linking the program with functions that are needed from the  C Library

4) Executing the Program.

Ms Dos operating system would load program stored inthe file .c  generate the Object Code  this code stored in another file name is

.obj

which generate the executeable code with file name is  .exe

C Tokens

 text data, individualwords and puncuation marks are called tokens

c tokens are

 keywords

Constants

Strings

Operators

Keywords

 auto          double       int               struct

break          else             long            switch

case            enum         register      typedef

char            extern        return         union

const          float           short          unsigned

continue    for              signed        void

default       goto           sizeof          volatile

do               if                 static          while

Integer Constants

----------------------------

A integer constant refers to a sequence of digits. There 3 types

Decimal, octal and hexadecimal.

Decimal consists 0.......9 preceded by an + or – sign.

Hidden spaces, commas,and non-digit charagacter s are not permitted between digits.

23 567

20,000

$34909

An octal number consists of any combination of digits from the set 0 through 7 with a leading 0.

A sequence of digits preceded by 0x and 0X theymay also include alphabets A through F for a through f.ex:

0X2

0x9F

Real constants

Integer numbers are inadequate to represent quantities that vary coninuously. Such as distance , heights ,price etc...

0.003like

A real number may be expressed in decimal notation or an integer.

Like

0.65e4;

Single character constants

String constants

Backslash character constants

------------

‘\a’     bell.

‘\b’      backspace

‘\f’       form feed

‘\n’      new line

‘\t’      Harizantal tab;

‘\v’        vertical tab;

‘\”        single quote

‘\” ‘               double quote

Data types

--------------

Primary data types

Intger

Singen type     unsigned type

Int           unsigned int

Short int            unsigned short int

Long int                   unsinged long int

Float

Float

Double

Long double

Ranges

Char                -128  to 127

Int                                  -32,768 to 32,767

Float             3,4e-38 to 3.4e+38

Double            1.7e-308 to 1.7e+308

Size and Range of Data Types(bits)

Char                     8      -128 to 127

Int                        16      0 to 255

Short Int      8       -128 to 127

Long         32       -2,147,483,648 to 2,147,483,647

Float         32       3.4E-38 to 3.4e+38

Double        64       3.4E-4932 to 1.1E+4932

How we Declare a Variable

After design a suitable variable names

1). It tells the compiler what the variable name

2) It specifies what type of data the variable will hold.

Data – type v1,v2,v3;

Int  count;

Double ratio;

Typedef

C supports a feature as type definition that allows users to define an identifier that would represent an existing data type.

 Typedef      type      identifier

Typedef  int  units;

Main()

{

Float x;

Double y;

Long int n;

Printf(“%f”,x);

Printf(“%lf”,y);

Printf(“%ld,n);

}

Declaring a variable as constant

The value of certain variables to remain constant during the execution of a program.

Const int size=30;

Printf syntax;

Scanf syntax;

  CHAPTER 2

C  supports  set of operators. Like are =,+ -  * & and < >

1)   Arithmetic operatos

2)   Relational operators.

3)   Logical operators.

4)   Assignment operators.

5)   Increment and decrement operator

6)   Conditional operator

7)   Bitwise operators

8)   Special operators.

ARITHMETIC OPERATORS

 C language provide  basic operators are  +, -, /, %, *

+                 -----------     Addition

-               ------  subtraction

*      ----   multiplication

/     ------   division

%   ------ modulo division

Modulo division operator % cannot be used on floating point data.

Ex:   a+b;

Here a,b are operands.

Integer arithmetic always get an integer value.

If a=14 , b=4 then

a-b=10;

a+b=18;

a*b=56;

a/b=3

a%b=2(remainder)

if you give like this

6/7=0;

If u give like

-6/-7=0;

RELATIONAL OPERATORS

 These operator used for compare two depending on their relation. Take certain decisions.

The operators are

Operator	Meaning
<	less then
<=	Less then or equal
>	greaterthen
>=	Greaterthen or equal
==	Equal to
!=	Not equal to

Logical operators

&&         ----   logical AND

||          ----  logical OR

!             ---   logical NOT

The logical && and || are used for test more than one condition and make ecisions.

a>b  &&x==10

ASSIGNMENT OPERATORS

 To assign the result of an expression to a variable.

Assign operator =

Ex;

X=x+20;

We can write like this

X+=20;

INCREMENT AND DECREMENT OPERATOR

 The increment and decrement are 4 types

Pre increment     ++p;

Post increment      p++;

Pre decrement      --p;

Post decrement       p--;

These operator used for while looping to automatically increment are decrement a value.

CONDITIONAL OPERATOR

 A ternary operator used for to test a single condition

Exp1 ? Exp2 : exp3;

X=(a>b)?a:b;

BIT WISE OPERATORS

 This is used for manipulation of data at bit level these operator  used for testing the bits,

Shift bit s left to right or right to left

Bitwise opertors are not used on float or double.

& ,| , ^ ,<<, >>,~