int is_square(rectangle r) 
{
    int height, width;
    width = r.ur.x - r.ll.x;
    height = r.ur.y - r.ll.y;
    /* The rectangle is a square if the width and height are the same,
    ** (width==height) will be 1 if they're equal, 0 otherwise.
    */
    return (width == height);
}