title: Unresolved Externals
body: <p>I am working on a simple top down shooter and wanted to move my ships to a separate ShipManager class, where I can manage all of them from a single location. However, upon starting this I get a linker error on my playerShip:</p>
  
  <p>error LNK2001: unresolved external symbol "public: static class Ship * ShipManager::playerShip"</p>
  
  <p>ShipManager.h looks like this:</p>
  
  <pre><code>class Ship;
  
  class ShipManager
  {
  public:
  static Ship*    playerShip;
  };
  </code></pre>
  
  <p>I have nothing in the ShipManager .cpp yet. What am I missing? The only other place I use this code is in my game class where I am actually calling ShipManager::playerShip, and I don't get any errors there. </p>
  
  <p>I include "ShipManager.h" in my game.cpp, so it should find it right? I have a feeling I'm forgetting something simple in this class.</p>