http://vegard.wiki/mediawiki/index.php?action=history&feed=atom&title=is_set%28%29 2026-07-04T15:52:17Z Revision history for this page on the wiki MediaWiki 1.41.1 http://vegard.wiki/mediawiki/index.php?title=is_set()&diff=231&oldid=prev 2020-03-01T11:56:38Z

<p>new page</p> <p><b>New page</b></p><div>{{DISPLAYTITLE:is_set()}}<br /> The following macro checks if another macro is set to 1 and works both in &lt;code&gt;#if&lt;/code&gt; preprocessor expressions and in actual C code:<br /> <br /> &lt;source lang=&quot;C&quot;&gt;<br /> // https://stackoverflow.com/a/10119699/1697183<br /> // https://news.ycombinator.com/item?id=3830609<br /> // https://github.com/torvalds/linux/commit/69349c2dc01c489eccaa4c472542c08e370c6d7e<br /> #define is_set(macro) is_set_(macro)<br /> #define macrotest_1 ,<br /> #define is_set_(value) is_set__(macrotest_##value)<br /> #define is_set__(comma) is_set___(comma 1, 0)<br /> #define is_set___(_, v, ...) v<br /> &lt;/source&gt;<br /> <br /> [[Category:C]]<br /> [[Category:Programming]]<br /> [[Category:C preprocessor snippets]]</div>

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