C/Pointer/Pointer Long

What"s the pointer

<source lang="cpp">

1. include <stdio.h>

void main() {

  long num1 = 0;
  long num2 = 0;
  long *pnum = NULL;
  pnum = &num1;    /* Get num1"s address     */
  *pnum = 2;       /* assign 2 to num1       */
  ++num2;          /* Increment num2         */
  num2 += *pnum;   /* Add num1 to num2       */
  pnum = &num2;    /* Get address of num2       */
  ++*pnum;         /* Increment num2 indirectly */
  printf ("\nnum1 = %ld  num2 = %ld  *pnum = %ld  *pnum + num2 = %ld\n",
                                     num1, num2, *pnum, *pnum + num2);

}

      </source>