#include <stdio.h>

void swap(int* x,int* y)
{
 int temp;

 temp = *x;
 *x   = *y;
 *y   = temp;
}

int main(void)
{
 int a=7,b=17;

 printf("a=%d b=%d\n",a,b); /* a=7 b=17 */

 swap(&a,&b);

 printf("a=%d b=%d\n",a,b); /* a=17 b=7 */

 return 0;
}