/* 
	Example: Using pointers
	Source: K&R2, p95-96
	Modified by Peter Brusilovsky
	Objective: use of addresses in function arguments
 */

#include <stdio.h>
void bad_swap(int x, int y);
void good_swap(int *p1, int *p2);

main() {
	int a = 1, b = 999;
	
	printf("a = %d, b = %d\n", a, b); 
	bad_swap(a, b);
	printf("a = %d, b = %d\n", a, b); 
	good_swap(&a, &b);
	printf("a = %d, b = %d\n", a, b); 
}

/* bad example of swapping - a function can't change prameters */
void bad_swap(int x, int y) {
	int temp;
	
	temp = x;
	x = y;
	y = temp;
}

/* good example of swapping - a function can't change prameters
   but if a parameter is a pointer it can change the value it points to */
void good_swap(int *px, int *py) {
	int temp;
	
	temp = *px;
	*px = *py;
	*py = temp;
}