Pointer arithmetic

Incrementing pointer 

Lets look at a simple code snippet

#include <stdio.h>

int main()
{
    int arr[3]={1,2,3} , *ptr;
    
    ptr = arr;                                    //array name is its base address
    printf("Base address of array = %p",ptr);
    
    ptr = ptr + 1;
    
    printf("\nAddress after incr = %p",ptr);
    
    return 0;
}

O/p

Base address of array = 0xbfa13b04
Address after incr = 0xbfa13b08

As ptr is an integer pointer , ptr = ptr + 1 ,increments ptr by 4 bytes and not 1 byte.

Decrementing pointer

In the above code just change ptr=ptr+1 to ptr=ptr-1

Subtraction of 2 pointers

 ptr=ptr + 1 - ptr + ptr;
 printf("%d",*ptr);

ptr is pointing to the 1st element of arr i.e 2 and so *ptr prints 2.

Addition of 2 pointers 

It is not allowed.But you can have an integer and pointer as 2 operands for + operator. (i.e  ptr + 1 is allowed as seen previously).

Multiplication and division

These operators can’t have 2 pointers as their operands and also they can’t have an integer and pointer as their operands. ( ptr = ptr * 1 and ptr = ptr/1 is also not allowed)