title: How to enable __int128 on Visual Studio?
body: <p>When I type <code>__int128</code> in a C++ project in Visual Studio, the editor changes color of <code>__int128</code> to blue (like keyword).</p>
  
  <p>But when I compile the source, the folowing error appears:</p>
  
  <pre><code>error C4235: 
  nonstandard extension used : '__int128' keyword not supported on this architecture
  </code></pre>
  
  <p>How can I enable <code>__int128</code> on Visual Studio?</p>