1. Tejalal Choudhary “C Programming from Scratch” Pointers
Department of Computer Science & Engg
SDBCT, Indore

2. Contents What is pointer Printing values using pointer
Call by reference
Pointer arithmetic
array and pointer
Structure and pointer

3. Int a=10; Int b=4; char ch=‘A’ 1 2 3 4 5 6 7 12 13 18 24 19 a … …
65529
65524
65535
65530 b ch

4. Recalling variable What does above declaration mean? int a=10;
a is an integer variable
Reserves 2 bytes in memory
Associate the name a with memory location
a will have some address

5. Address of Operator(&)
The & operator is used to access the address of a variable
The %u is used to print the address with &
int a=10;
Following statement will print the address of variable a
printf(“Address of a=%u”, &a);

6. Value at address operator(*)
Gives the value stored at a particular address
Also known as indirection operator.
int a=10;
The following statements will print the value of a
printf(“Value of a=%d”, a); //10
printf(“Value of a=%d”, *(&a)); //10

7. What is a pointer ? Declaration: int *p;
Pointers are variables that contain addresses
Pointers would always contain whole numbers.
A pointer when incremented always points to an immediately next location of its type.
A pointer is a variable which holds/stores the address of another variable
Declaration: int *p;
p is a pointer variable which can store address of any integer variable
Pointer variable can not store normal values
p=3456; // not allowed
P=&a; //allowed if a is an integer variable

8. int i = 3;
int *j;
int **k ;
j=&i;
K=&j;

9. } j = &i ; k = &j ; printf ( "\nAddress of i = %u", &i ) ;
int i = 3, *j, **k ;
j = &i ;
k = &j ;
printf ( "\nAddress of i = %u", &i ) ;
printf ( "\nAddress of i = %u", j ) ;
printf ( "\nAddress of i = %u", *k ) ;
printf ( "\nAddress of j = %u", &j ) ;
printf ( "\nAddress of j = %u", k ) ;
printf ( "\nAddress of k = %u", &k ) ;
printf ( "\nValue of j = %u", j ) ;
printf ( "\nValue of k = %u", k ) ;
printf ( "\nValue of i = %d", i ) ;
printf ( "\nValue of i = %d", * ( &i ) ) ;
printf ( "\nValue of i = %d", *j ) ;
printf ( "\nValue of i = %d", **k ) ; }
65524
65524
65524
65522
65522
65520
65524
65522 3 3 3 3

10. Call by reference s=sum(&a, &b);
Arguments can be passed to functions in one of the two ways:
Sending the values of the arguments
Sending the addresses of the arguments
int a=10, b=20, s;
s=sum(&a, &b);
Function definition
int sum(int *p, int *q) {
int r=*p+*q;
return r; }
Passing the addresses of a & b
We are passing addresses, we need pointer variable. p & q are pointer

11. Pointer arithmetic Addition of two pointers
Don’t attempt following operations on pointer
Addition of two pointers
Multiplication of a pointer with a constant
Division of a pointer with a constant
All of the above

12. What will be the output of the program?
void main(){
 int i = 3, *x ;
float j = 1.5, *y ;
clrscr();
x = &i ;
y = &j ;
//suppose address of i=200 and address of j=400
x++ ;
y++ ;
printf( "\n %u ", x ) ;
printf( " %u", y ) ;
 getch(); } 

13. What will be the output of the program?
#include<stdio.h>
#include<conio.h>
void main( ) {
int i = 3, *j, **k ;
clrscr();
j = &i ;//suppose address of i is 200
k = &j ;//suppose address of j is 400
printf ( "\n%u", j ) ;
printf ( ",%u", k ) ;
printf ( ",%d", * ( &i ) ) ;
printf ( ",%d", **k ) ;
getch(); }