It&#x27;s &quot;one local variable&quot; in the same way as<p><pre><code>    struct {
        unsigned int theint:31;
        unsigned int thebool:1;
    } myvar;
</code></pre>
and the code probably uses multiple CPU registers to do the abs(), the calculation of addresses for the XOR swap, etc. but still interesting just for the artificial constraint part of &quot;can it be done&quot;.<p>Aside: this is one of those pages that shows everything <i>but</i> the actual post content(!) if you have JS disabled. And if you view the source code... you&#x27;ll find a huge JSON object with the actual content, apparently just pure HTML embedded as a string inside it.<p><i>Note to readers: I am looking into a different platform for publishing my computer science articles. The current platform I am using is easy to use. However, it has its limitations. Not the least of which is the inability to use custom HTML where it is useful. This makes me unable to embed nice code snippets in my articles.</i><p>How about a simple HTML page?