title: how this function read text into a struct?
body: <p>I am trying to understand what exactly the following function is doing. It is used to read a text file into a <strong>struct</strong>, called <code>AEntry</code>, which only contains four ints. </p>
  
  <p>The file contains a list of lines. Each line holds four ints delimited with <strong>spaces</strong> (or <strong>tab</strong>). </p>
  
  <p>when this function is called, a line of <code>istream</code> and a <code>AEntry</code> <code>struct</code> are passed in. </p>
  
  <p>My question is how the delimitors, spacess or tabs, are filtered out? or my understanding is wrong.</p>
  
  <pre><code>istream&amp; operator&gt;&gt;( istream &amp;stream, AEntry&amp; val )
  {
      stream &gt;&gt; val.kv;
      stream &gt;&gt; val.col;
      stream &gt;&gt; val.bo;
      stream &gt;&gt; val.Offset;
      return stream;
  }
  </code></pre>