title: Error: expected a declaration
body: <p>So far all I have in my <code>DecisionTree.h</code> file is </p>
  
  <pre><code>namespace DecisionTree
  {
       public static double Entropy(int pos, int neg);
  }
  </code></pre>
  
  <p>and Visual Studio is already highlighting the <code>public</code> and saying</p>
  
  <blockquote>
    <p>Error: expected a declaration.</p>
  </blockquote>
  
  <p>What am I missing?</p>