void swap(a,b)
	int *a,*b;
{	int c;
	c  =*a;
	*a =*b;
	*b =c;
	return;
}
main()
{
	int x,y;
	x = 9;
	y = 7;
	printf("x== %d, and y== %d\n",x,y); 
	swap(&x,&y);
	printf("x== %d, and y== %d\n",x,y);
}