C Language

Let us start Our C. 



First of all I will tell you that C is a high level language,
which developed by Dennis Ritchie, in 1972, in AT and T's bell laboratory California 
Now I will tell you about levels of language----->> 
We generally have two level of language-->
                                        LOW LAVEL            and       HIGH LAVEL 
A low level language->
                       To code in a low level language we have a good knowledge of hardwares 
                       because it is a Machine dependendent language.
                       without a knowledge of hardware we coud't use a low level language.
High level language->
                      High level language is that language which does not depend on any hardware.
                      or we can say that a user does not need any knowledge of hardware.
                      because a high level language is developed that any user can use that without any knowledge of hardware.
                      I hope you understand what would I want to say by using these words 
That's the different thing that a low level language is easily understood by computer.
Or we can say the machine but a high level language is easily understand by us 
that is why all the language which are consider in programming are in high level. 
Now I will tell you something about some word which are already fixed for some purpose are known as keyword we have 32 keywords in C. 
Auto      double    int         struct      break      elss 
Long      switch    case        enuam       register   typedef 
Char      extern    return      union       const      float 
Short     unsigned  continue    four        signed     void 
Default   goto      Sizeof      Volatile    do         If
Static    while
Now I will tell you a lot talking about the characters of c 
Alphabets   A,B,C ......Z   or a, b, c........z 
Digits      .....-9,-8,-7,-6,-5,-4,-3,-2-1,0, 1, 2, 3, 4, 5, 6, 8, 9,...... 
Symbols   !  @  #  % ^  &  * ()  _  +  -  =  ;  :  '   "  ....... 
NOTE:-> 
we can we can use any kind of symbol in C language except with Dollar sign ($) this sign is not Allow in C language.
Now I will tell you where we can write C program--> 
I advise you to use code block either in Windows and Linux turbo C also used as compiler in which we can write our c program.
But if you are using Linux then builder in the best choice or we can say a best platform to write your program. 
In Linux we use  a command gcc name of programc.c   and a command  ./a.out to run our program. 

structure of a program==>>
#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf("hello word");
getch();
}


This program arising a lot of questions in your mind 

well these questions are arise in my mind also  that 

what is  #include ?

and all the things written in the program. 


Now I will tell you everything about it clearly==>>
 
The symbol (#) known as hash or called  a preprocessor  in c. 
And the written word (include) with symble is called an derivative. 

  When both include and hash(#) combine they form a preprocessor derivative. 
which connects a library to our programe. And the library name which we connect to a program is <stdio.h>.

 
Now I will tell you what is a C librarie==>
 A c librari in actual it is a file contains some function of c which are used by us in a program.
 we even create our own c library by using the extension .h.


This library will contain the 

printf("") functions These function are contained by this library.
and the function void main is also from the same library.


The first function printf()  ==>

This function is used while we want to print something on the screen As our first program that we print hello world.
we write hello world into function printf() to print hello.


One more thing about the program the semi colon (;) which is used in the last of each and every line
in a program is known as Terminator in C language it is used at the end of every statement.

 
while we finish our program or start our program we use a pair of curly brackets {} affter main function. 
this pare which tell that our main
function is being start and at end it tell that our function is over. 


Now you will see that one more library is connected by us that is <conio.h> this library with 
contain the clrscr() and getch() function 

now I will tell you the use of these function.
 
 
 
The function clrscr() is use to clear the screen. 
If you don't understand what is this clear screen then don't get nervous because I will tell you about it in other programs. 
And this the last function getch()==>

Is used to store our result if we do not use this function then our .exe extension of program does not so any result. 
I hope now you will understand everything about our first program the hello world.
You still you have any problem then you can contact us. 


I am writing some questions you have to go to code them. 
Questions 
1 write a program to show        i  love my country. 
2 write a program which show     early to bed early to rise makes a man healthy wealthy and wise.
3 write a program which show      my name is vipin 
                                  i belong to india

answers
1  
#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf("i  love my country ");
getch();
}



2

#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf("early to bed early to rise makes a man healthy wealthy and wise.");
getch();
}


3

#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf("my name is vipin \n i belong to india");
getch();
}

OR

#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
printf("my name is vipin");
printf("i belong to india");
getch();
}

As you can see in 3rd question I use \n  what's this combination is used to print something from a new line. 
Is combination are called escape sequence Many more combination are there like. 
\t   
\v 
\b 
\a 
You can use any sequence
to make your program better or to give a special effect to your program you can try all these by you yourself. 

Using variables.


C variable is nothing but it is just a name is given to any data type.

It also have some rules - ---->

It does not contain any other character except underscore.

It should not be a keyword of c.

it should not be larger than 32 words.

NOTE:===>> name of variable shoud be of your choice.


now i will tell you what a data type is ===>

A data type is nothing it is just a type of data like if integer character decimal number and Many other kind of data.

Let us discuss diffrent type of data types.......

                     PRIMARY DATA TYPE                AND                    SECONDARY DATA TYPE    

PRIMARY DATA TYPE  ======>>>>

Integer --->
            It is Kind of data type which tell that a integer is being used in a program
            in easy language we can say that a number is use in our program.

Character data type --->
                         It is a kind of data type which tell that a character
                         even that is symbol for a letter or an alphabet is used in our program.

Double data type---- >
                     This data type tell us that a decimal number is being used in our program 
                     for printing for taking a decimal number from user
                     the same work is being done by float data type but
                     float data type round off our number and double data type does not round orf number.

Float data type --- >
                     It is also act as double data type it also tell that it is a molecule your program
                     but it round off that decimal number.

SECONDARY DATA TYPE  =====>
                                                              This data type use while we learn moduler progreaming
                                                               in c they form using primary data types.

Let us start learning using of data types=====>
 
Simple C program which accept a integer-- 

#include<stdio.h>
#include<conio.h>
void main()
{
clrscr();
int a;
printf(" enter a number \n ");
scanf("%d",&a);
getch();
}

As you can see we use another keyword of c name int. 

Have you remember that why we use int ? 

Because we are using an integer in a program. 

How to define a variable in C---> 
 
Simply we write the keyword for the data type of variable and write the name of variable as we have done in a program. 

int a;                 =====>  hear we defin a variable name a;

Haven't I tell you about scanf() function till now . 

Now you will learn use of scanf() function---> 

It is a function which we use while taking input from user it has a specific format 
First of all we have to write scanf("") with invited coma ("") and in invited comma   
THen We have to use 

%d  for integer 
%c  for character 
%f  for float 
%lf for double 

As you can see we are using an integer program that is why we use %d 
And then we use a (,) affter invited comma (scanf("%d",)) and then we use this symbol (&) 
scanf("%d",&)  
This symbol will locate our variable into the memory of computer or simply we can say provide address to our variable. 

scanf("%d",&a)   HEAR a IS THE NAME OF VAREABLE GIVEN BY US.

now I will tell complit function again 

in Starting we write scanf()  then use invited commas then we use symbol (&)  and then use comma 
and then write the name of our variable which we define above.
Now we will start how to take a number and print in a program .

#include<stdio.h>
#include<conio.h>

void main()
{
clrscr();
int a;
printf(" enter a number \n ");
scanf("%d",&a); 
printf(" entered number is %d \n ",a);
getch();
}
As you can see we again use %d in our program in function printf("%d",a) ;
One more time you will notice that we does not use the symbol (&) hear 
because  here the function will automatically 
find the location of     a     and print the number  on the screen.


Now we will start how to take a float and print a float in a program .

#include<stdio.h>
#include<conio.h>

void main()
{
clrscr();
float a;
printf(" enter a decimal number \n ");
scanf("%f",&a); 
printf(" entered float is %f \n ",a);
getch();
}
As you can see we again use %f in our program in function printf("%f",a) ;
One more time you will notice that we does not use the symbol (&) hear because  here the function will automatically find the location of     a     and print the chracter on the screen.




Now we will start how to take a character and print a character in a program .

#include<stdio.h>
#include<conio.h>

void main()
{
clrscr();
char a;
printf(" enter a chracter \n ");
scanf("%c",&a); 
printf(" entered character is %c \n ",a);
getch();
}
As you can see we again use %c in our program in function printf("%c",a).


Now we will start how to take a double number and print a double number in a program .

#include<stdio.h>
#include<conio.h>

void main()
{
clrscr();
double a;
printf(" enter a double number \n ");
scanf("%lf",&a); 
printf(" entered double number is %lf \n ",a);
getch();
}
As you can see we again use %lf in our program in function printf("%lf",a) ;
And now we will discuss about operators in C. 

Generally we have three types of operator=====>>>>> 

1   Unary operator 

2   Binary operator 

3   Ternary operator or conditional operator

Unary operator -----> 
                     Unary operators are used only single operands
                     For example (), []  ,  {}  etc. 

Binary operator----> 
                    Binary operator need two operands 
                    For example  addition ,subtraction, multiplication  etc. 

Ternary operator---> 
                    This operator need three operands to work one is condiction 
                     and two are expresion. We will deeply study while we make some programs 
                     on it.





Arithmetic operaters---> 
                         Arithmetic operators are you to perform any mathematical operation 
                         Like 
                           + adding 
                           - subtracting 
                           * multiply 
                           / divide 
                           % finding remainder.{10%3=1(remainder)} 
ther all are arthmatic operater type of binary operater.


Relational operators===>> 
                         From it's come in the name of operator this operator show any 
                         relation between two operands. 
<   less then 
>   greater then 
==    equal to 
<=  less than equal to 
>=  greater than equal to 
!=  no equal to 

They are also binary operator 

Logical operator=====> 
                       We have three kind of logical operator in C. 
A   &&  and operator 
B   ||  or operator 
C    !  not operater 



Sizeof() operator =====> 
                         This operator tell us the size of a data type. 
                         We will discuss it later while we may program on operator.