title: What does "default" mean after a class' function declaration?
body: <p>I've seen <code>default</code> used next to function declarations in a class. What does it do?</p>
  
  <pre><code>class C {
    C(const C&amp;) = default;
    C(C&amp;&amp;) = default;
    C&amp; operator=(const C&amp;) &amp; = default;
    C&amp; operator=(C&amp;&amp;) &amp; = default;
    virtual ~C() { }
  };
  </code></pre>