<pre><code>#if SYMBOL
  //code
#endif
</code></pre>

<p>what values does C# predefine for use?</p>

[{'answer_id': 21467, 'author': 'Nick', 'author_id': 1490, 'author_profile': 'https://Stackoverflow.com/users/1490', 'pm_score': 2, 'selected': False, 'text': '<p>Depends on what /define compiler options you use.  <code>Visual Studio</code> puts the <code>DEBUG</code> symbol in there for you via the project settings, but you could create any ones that you want.</p>\n'}, {'answer_id': 21479, 'author': 'Frank Krueger', 'author_id': 338, 'author_profile': 'https://Stackoverflow.com/users/338', 'pm_score': 3, 'selected': True, 'text': '<p>To add to what Nick said, the MSDN documentation does not list any pre-defined names. It would seem that all need to come from <code>#define</code> and <code>/define</code>.</p>\n\n<p><a href="http://msdn.microsoft.com/en-us/library/4y6tbswk.aspx" rel="nofollow noreferrer">#if on MSDN</a></p>\n'}, {'answer_id': 21502, 'author': 'dguaraglia', 'author_id': 2384, 'author_profile': 'https://Stackoverflow.com/users/2384', 'pm_score': 0, 'selected': False, 'text': "<p>Well, that depends on the compiler you are using, and the command line options. Mono defines different names than Microsoft's compiler by default, and depending on what system you are you get different defines, etc.</p>\n\n<p>If you provide a more specific system for which you are compiling, we might be able to come up with the list for that particular system (for example: x64 Vista system, using Visual Studio 2008).</p>\n"}]
['https://Stackoverflow.com/questions/21461', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/1343/']