title: What does third 'for' mean in #define for for(int z=0;z<2;++z)for
body: <p>I have found a piece of code in a C++ program, it seems that it loops two times every <code>for()</code> loop in this program, but why does it need this third for in such preprocessor definition? </p>
  
  <p><code>#define for for(int z=0;z&lt;2;++z)for</code></p>