of three implementation
files: two C files, <code id='code28736'
>cpoint.h</code> and <code id='code28737'
>cpoint.c</code> and one Scheme
file <code id='code28738'
>spoint.scm</code>. Here are defined the three files:<br/><br/><code id='code28740'
>cpoint.h</code>:<center id='center28743'
><table cellspacing="0" class="color" cellpadding="0" width="95%"><tbody>
<tr><td bgcolor="#ffffcc"><pre class="prog" id='prog28741'
>struct point_2d {
   double x, y;
};
</pre>
</td></tr>
</tbody></table></center>

<code