C programming Pointer Basic

c pointer tutorial pdf,pointer in c pdf yashwant kanetkar notes ,pointer in c pdf free download ,pointer in c language pdf,pointer in c programming pdf,pointer in c ppt


Learn and Understand Pointer Basic 

Click here Pointer Basic Notes Pdf Download

Definition of pointer: Pointers are variable but different than normal variable because it store address of another variable.

How to declare Pointer variable and how it works

You must know two operators

* Value at

& Address of

We can declare pointer variable using * asterisk symbol

Int * ptr, a=5;

Here * ptr is pointer declaration, a is common integer variable to understand this concept lets execute simple program

_________________________________

#inclue

#include

void main()

{   int * ptr, a;

  clrscr();

  printf(“a=%d”, a);

  printf(“&a=%d”,& a);

  printf(“ptr=%d”, ptr);

  printf(“&ptr=%d”,& ptr);

  printf(“*ptr=%d”,*ptr);

getch();

}

 After execution of this program what is result

Output is like this

a= -20476

&a=-12

Ptr = 12803

&ptr=-14

*ptr=-20476

 Let’s see explanation of this program

Output shows garbage values and cell address of variable

As in our program we don’t have initialized variable I, e, a and pointer that’s why this result came.

As shown in figure

In computer memory cell will allocated as follows

Each cell has address i. e number value 

As shown

a= -20476                  &a=-12

ptr = 12803             &ptr=-14

_____________________________

*ptr=-20476?????

As ptr is pointer variable it will point to something we didn’t yet initialized ptr so by default it is pointing to some garbage value that’s why this output come.

_________________________________

 Lets we initialize pointer and variable pointer a

#include

#include

void main()

{ int a,*ptr;

  printf(" \n \t after initialization");

     a=5;     ptr=&a;

 printf("\n \t\ta=%d",a);

 printf("\n \t\t&a=%d",&a);

 printf("\n \t\tptr= %d",ptr);

 printf("\n \t\t*ptr=%d",*ptr);

 printf("\n \t\t&ptr= %d",&ptr);

  printf("\n \t\t*(*(&ptr))= %d",*(*(&ptr)));

 getch();

}

As we use & to initialize pointer as follows

a=5, ptr=&a;

Let’s see memory structure

 Before initialization

After initialization

In above diagram  lets we check the output of some printf statements

A=5

&a=-12

Ptr=-12

&ptr=-14

*ptr=5

*(&ptr)=-12  eg. (*(-14))=-12

*(*(&ptr)=5

To print the address of any variable of type pointer which thing we should use

%u treats the integer as unsigned, whereas

 %d treats the integer as signed. 

If the integer is between 0 an INT_MAX (which is 231-1 on 32-bit systems), then the output is identical for both cases.

It only makes a difference if the integer is negative (for signed inputs) or between INT_MAX+1 and UINT_MAX (e.g. between 231 and 232-1).  In that case, if you use the %d specifier, you'll get a negative number, whereas if you use %u, you'll get a large positive number.

Pointer Basic Notes Pdf Download

c pointer tutorial pdf,pointer in c pdf yashwant kanetkar notes ,pointer in c pdf free download ,pointer in c language pdf,pointer in c programming pdf,pointer in c ppt