swap(int *a,int *b)
{
    int t;
    printf("(2)*a=%d *b=%d\n",*a,*b);
    t=*a;
    *a=*b;
    *b=t;
    printf("(3)*a=%d *b=%d\n",*a,*b);
}

main()
{
    int x=20,y=30;
    printf("(1)x=%d y=%d\n",x,y);
    swap(&x,&y);
    printf("(4)x=%d y=%d",x,y);
    getch();
}