title: Why isn't there int128_t?
body: <p>A number of compilers provide 128-bit integer types, but none of the ones I've used provide the typedefs <code>int128_t</code>. Why?</p>
  
  <p>As far as I recall, the standard</p>
  
  <ul>
  <li>Reserves <code>int128_t</code> for this purpose</li>
  <li>Encourages implementations that provide such a type to provide the typedef</li>
  <li>Mandates that such implementations provide an <code>intmax_t</code> of at least 128 bits</li>
  </ul>
  
  <p>(and, I do not believe I've used an implementation that actually conforms to that last point)</p>