title: Implementing a map using doubly linked list
body: <p>I am trying to implement a map using a template-doubly linked list.</p>
  
  <p>I am trying to write a get function: </p>
  
  <pre><code>valueType get (keyType key, bool &amp; success) const;
  </code></pre>
  
  <ul>
  <li><p>Returns the value associated with the given key.</p></li>
  <li><p>If the key existed in the map, success should be set to true.</p></li>
  <li><p>If the key has no association, it should set success to false. </p></li>
  </ul>
  
  <p>The get function will be used for the user to access the map, and for the <code>add()</code> and <code>remove()</code> functions that want to check whether or not there is an association between the given key and a value. </p>
  
  <p>I am confused about what I return if the value does not exist? Because, this function returns type <code>valueType</code></p>