Call By Reference in C

/* Program for inerchanging two numbers demonstrating Call By Reference in C */

#include<>
#include<>

void swap(int *,int *);

void main()
{
int x,y;
x=15;y=20;
clrscr();
printf("x=%d,y=%d\n",x,y);
swap(&x,&y);
//printf("\n%x %x",&x,&y);
printf("\n after interchanging x=%d,y=%d\n",x,y);
getch();
}

void swap(int *u,int *v)
{
int temp;
temp=*u;
*u=*v;
*v=temp;

return;
}