Pointer arithmetic getting wrong output [duplicate]

Answer 1

The result of one pointer minus another pointer is the number of elements between them, not the number of bytes.

int **ptr=p;
ptr++;

ptr moves forward one element, so ptr - p has a value of 1.

BTW, this behavior is consistent with ptr++ (which means ptr = p + 1; in your example.

Answer 2

Subtraction of a pointer from another pointer of same base type returns an integer,which denotes the number of element of that between the two pointers.

If we have 2 pointer two int pointers p1 and p2, containing addresses 1000 and 1016 respectively, then p2-p1 will give 4 (since size of int 4).

Answer 3

When you find the difference between two pointer you will get the number of objects between them. In this case as the objects are of type integer you correctly got the value 1.

If you want to know the value in terms of bytes then you should do:

printf("%d",(char *)ptr-(char *)p);

It will print 4.