Pointer arithmetic in C

#include<stdio.h>
int main()
{
  int a=24;

  int* ptra = &a;
  char b='3';
  char* ptrb=&b;
  printf("%d\n\n",ptrb);  //size of char is 1
  ptrb++;
  printf("%d\n\n",ptrb);   // add 1 to &b
  ptrb--;
  printf("%d\n\n",ptrb+1);  // add 1 to &b
  printf("%d\n\n",ptrb-1);  // subtract 1 to &b
  printf("%d\n\n",ptrb+1);  // add 1 to &b
  printf("%d\n\n",ptrb-2);  // subtract 2*1 to &b
  printf("%d\n\n",ptra);
  printf("%d\n\n",ptra+1); // size of int is 4 so, it add 4 to &a/ptra
  printf("%d\n",ptra-2); // size of int is 4 so, it subtract 2*4 to &a/ptra
  return 0;
}