title: What does this function ft_isalnum do?
body: <p>I am reading a program which contains the following function, which is</p>
  
  <pre><code>int ft_isalnum(int c)
  {
      return ((c &gt;= 'a' &amp;&amp; c &lt;= 'z') || (c &gt;= 'A' &amp;&amp; c &lt;= 'Z')
              || (c &gt;= '0' &amp;&amp; c &lt;= '9'));
  }
  </code></pre>
  
  <p>I don't quite understand what does this function intend to do?</p>