title: Why is isascii() deprecated?
body: <p>According to the isascii() manpage:</p>
  
  <p><a href="http://linux.die.net/man/3/isascii">http://linux.die.net/man/3/isascii</a></p>
  
  <blockquote>
    <p>POSIX.1-2008 marks isascii() as obsolete, noting that it cannot be
    used portably in a localized application.</p>
  </blockquote>
  
  <p>I'm not sure I see where the portability problem is. A very simple implementation of this function is:</p>
  
  <pre><code>int isascii(int ch) { return ch &gt;= 0 &amp;&amp; ch &lt; 128; }
  </code></pre>
  
  <p>In which situations is the above implementation either not sufficient or not portable?</p>
  
  <p>Thank you</p>