title: Why would somebody use an #if 1 C preprocessor directive?
body: <p>I am looking through some <strong>C</strong> source code and I don't understand the following part</p>
  
  <pre class="lang-c prettyprint-override"><code>#if 1
  
     typedef unsigned short PronId;
     typedef unsigned short LMId;
  #  define LM_NGRAM_INT
  
  #else
  
     typedef unsigned int LMId;
     typedef unsigned int PronId;
  #  undef LM_NGRAM_INT
  
  #endif
  </code></pre>
  
  <p>Why would someone do <code>#if 1</code>? Isn't it true that only the first block will ever be processed?</p>