title: What does & mean in fileStat.st_mode & S_IRUSR
body: <p>I am trying to print the permissions of files in <code>Linux</code> using <code>stat</code> function call in <code>C</code>. And I found some useful code online which has the segments</p>
  
  <pre><code>printf( (fileStat.st_mode &amp; S_IRUSR) ? "r" : "-");
  printf( (fileStat.st_mode &amp; S_IWUSR) ? "w" : "-");
  </code></pre>
  
  <p>The code works perfect, but could anyone explain me what does the <code>&amp;</code> mean here?</p>