A pointer is a variable which is used to store the address as a value of another variable. Pointers are helpful with program's efficiency and allow us to handle unlimited amounts of data.

The following operations are performed with pointers:

1. Addition of a number to a pointer variable:

Suppose p is a pointer variable pointing to an element of integer type, then the statement p++; increments the value of p by a factor of 2, so that it points to the next location that holds another value of integer type. This increment factor will be 1 for character, 4 for long integer and float, and 8 for long float. The statement p+=I; where I is either a positive integer constant or an integer variable having positive value, increments p such that it points to the ith location beyond the location to which it is currently pointing.

2. Subtraction of a number from a pointer variable:

Suppose p is a pointer variable pointing to an element of integer type, then the statement p--; decrements the value of p by a factor of 2, so that it now points to the location preceding the current location. The statement p-=I; where I is either a positive integer constant or an integer variable having positive value, decrements p such that it points to the ith location before the location to which it is currently pointing.

3. Subtraction of one pointer variable from another:

One pointer variable can be subtracted from another provided both point to the same data type. The difference of the 2 indicates the number of bytes separating the corresponding elements.

Example:

*(px+3)-(px+2)
=*(px+1)
= 8-6 = 2 bytes

Program to demonstrate the passing of an entire array using pointer notation.

#include<stdio.h>

void main()

    {

       int arr[10]={12,15,20,17,25,50,11,8,10,13};

       int i;

       int maximum(int *temp_arr, int size);          /*function prototype*/

       printf(\n largest of the array element is %d\n,maximum(arr,10));

     }

int maximum(int *temp_arr, int size)

    {

       int temp_max, i;

       for(temp_max = *temp_arr, i=1; i<size, i++)

       {

         if *(temp_arr + i) > temp_max)

         temp-max = *(temp_arr + i);

       }

       return temp_max;

    }