// ptr_ops -- pointer operations
#include <stdio.h>

int main(void)
{
	int urn[5] = {100, 200, 300, 400, 500};
	int * ptr1, * ptr2, * ptr3;
	
	// assign an address to a pointer
	ptr1 = urn;
	// ditto
	ptr2 = &urn[2];
	/* dereference a pointer and take the address
	   of a pointer */
	printf("pointer value, dereferenced pointer, pointer address:\n");
	printf("ptr1 = %p, *ptr1 = %d, &ptr1 = %p\n", ptr1, *ptr1, &ptr1);
	
	// pointer addition
	ptr3 = ptr1 + 4;
	printf("\nadding an int to a pointer:\n");
	printf("ptr1 + 4 = %p, *(ptr1 + 3) = %d\n", ptr1 + 4, *(ptr1 + 3));
	// increment a pointer
	ptr1++;
	printf("\nvalues after ptr1++:\n");
	printf("ptr1 = %p, *ptr1 = %d, &ptr1 = %p\n", ptr1, *ptr1, &ptr1);
	// decrement a pointer
	ptr2--;
	printf("\nvalues after --ptr2:\n");
	printf("ptr2 = %p, *ptr2 = %d, &ptr2 = %p\n", ptr2, *ptr2, &ptr2);
	// restore to original value
	--ptr1;
	// restore to original value
	++ptr2;
	printf("\nPointers reset to original values:\n");
	printf("ptr1 = %p, ptr2 = %p\n", ptr1, ptr2);
	// subtract one pointer from another
	printf("\nsubtracting one pointer from another:\n");
	printf("ptr2 = %p, ptr1 = %p, ptr2 - ptr1 = %d\n",
	       ptr2, ptr1, ptr2 - ptr1);
	// subtract an integer from a pointer
	printf("\nsubtracting an int from a pointer:\n");
	printf("ptr3 = %p, ptr3 - 2 = %p\n", ptr3, ptr3 - 2);
	
	return 0;
}