title: JSON for Modern C++ _json Syntax
body: <p><a href="https://github.com/nlohmann/json" rel="nofollow noreferrer">JSON for Modern C++</a> uses the following syntax:</p>
  
  <pre><code>json j = "{ \"happy\": true, \"pi\": 3.141 }"_json;
  </code></pre>
  
  <p>and I was wondering how they are accomplishing this.</p>
  
  <p>I don't understand the string literal _ json syntax.</p>