Pointer

Pointer
A pointer is a variable that stores memory address. Like all
other variables ,it also has a name, has to be declared and
occupies some space in memory. It is called pointer
because it points to a particular location in memory (by
storing the address of that location).
The expression having (*) operator is known as pointer
expression. Pointer is the variable that points to the
memory location of the next variable. So, we have to assign
address of a variable to the pointer variable.
Int a=5;
Int *p1=&a;
If we put *before p1, then, we can access the variable whose
address is stored in p1. since p1 contains the address of
variable a, we can access the variable a by writing *p1.

What are Pointers?
Pointers are different from other normal
variables. While other normal variables
store values, pointers are special variables
that can hold the address of a variable.
Since they store memory address of a
variable, the pointers are very commonly
said to “point to variables”.

Pointer
• A pointer is a variable which holds the address
of the storage location value for another given
variable.
• C provides two operators & and * which allow
pointers to be used in many versatile ways.
*:- is the value of address eg.*a
&:- is the address of variable eg. &a
*(&a):- we are using the value which is inside of
the address

pointer arithmetic operations are
allowed?
• A pointer can be incremented (++) or decremented (--)
• An integer may be added to a pointer (+ or +=)
• An integer may be subtracted from a pointer (- or -=)
• One pointer may be subtracted from another

In c programming every variable keeps two type of value.
1. Contain of variable or value of variable.
2. Address of variable where it has stored in the memory.
(1) Meaning of following simple pointer declaration and definition:
int a=5;
int * ptr;
ptr=&a;
Explanation:
About variable a:
1. Name of variable : a
2. Value of variable which it keeps: 5
3. Address where it has stored in memory : 1025 (assume)
About variable ptr:
4. Name of variable : ptr
5. Value of variable which it keeps: 1025
6. Address where it has stored in memory : 5000 (assume)

A normal variable ‘var’ has a memory address of 1001 and holds a
value 50.
A pointer variable has its own address 2047 but stores 1001,
which is the address of the variable ‘var’

Another example:
Int I, *j, **K;
Here I is dinary int ,J is a pointer to an int , whereas K is a pointer
to an integer pointer
3 65524 65522
i
65524
j
65522
65520
k

For example
a ) valid example
Int *p;
Int num;
P=&num;
b) Invalid example
Int *p;
Float num;
P=&num; /*as pointer variable p can not store address of float variable*/

Data type
Integer
Unsigned integer
Octal
Hexadecimal
Float simple
Float exponential
Character
string
Conversion Charater
D
U
O
X
F
E
C
S

#include <stdio.h>
#include <conio.h>
void main( )
{
int u = 36;
int *pu; /*pionter to an integer*/
clrscr();
pu=&u; /*assign address of u to pu*/
printf("nu=%d &u=%x *pu=%d",u,&u,*pu);
getch();
}

/* Illustration of pointer data type */
#include <stdio.h>
#include <conio.h>
void main( )
{
int u = 36;
int v;
int *pu; /* pointer to an integer*/
int *pv; /* pointer to an integer*/
clrscr();
pu = &u; /* assign address of u to pu */
v = *pu; /* assign address of u to v */
pv = &v; /* assign address of v to pv */
printf("nu = %d n&u = %x npu = %x n*pu = %d", u,&u, pu, *pu);
printf("nnv = %d n&v = %xn pv = %x n*pv = %d", v, &v, pv, *pv);
getch();

#include <stdio.h>
#include <conio.h>
void main()
{
int a,b,sum, *ptra,*ptrb;
a=20;
b=10;
ptra =&a;
ptrb=&b;
sum=*ptra+*ptrb;
printf("sum=%d",sum);
getch();
}
1. WAP to add value stored in two variable using pointer

Pointer

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Pointer