title: Assigning parameter value in function declaration?
body: <p>I don't understand why in this constructor declaration, the input parameter is assigned 2. </p>
  
  <p>What does it mean? Does it mean that by default (unless something else is passed), size will be 2?</p>
  
  <pre><code>Graph(int size = 2);
  </code></pre>
  
  <p>I've never seen syntax like this, so I don't even know how to Google it :/</p>
  
  <p>Thanks in advance!</p>