title: C memory space and #defines
body: <p>I am working on an embedded system, so memory is precious for me.</p>
  
  <p>One issue that has been recurring is that I've been running out of memory space when attempting to compile a program for it.  This is usually fixed by limiting the number of typedefs, etc that can take up a lot of space.</p>
  
  <p>There is a macro generator that I use to create a file with a lot of #define's in it.
  Some of these are simple values, others are boundary checks </p>
  
  <p>ie</p>
  
  <pre><code>#define SIGNAL1 (float)0.03f
  #define SIGNAL1_ISVALID(value) ((value &gt;= 0.0f) &amp;&amp; (value &lt;= 10.0f))
  </code></pre>
  
  <p>Now, I don't use all of these defines.  I use some, but not actually the majority. 
  I have been told that they don't actually take up any memory if they are not used, but I was unsure on this point.  I'm hoping that by cutting out the unused ones that I can free up some extra memory (but again, I was told this is pointless).</p>
  
  <p>Do unused #define's take up any memory space?  </p>