title: Inizialize a vector in the class constructor
body: <p>I have a class with a private attribute that is a vector. I'm Initializing it at null in the constructor like this:</p>
  
  <pre><code>Graph(int NumberOfVertices):vertices(NumberOfVertices),             
                                      edges(0),
                                      adjacency_list(NULL){};
  </code></pre>
  
  <p>the vector is</p>
  
  <pre><code>std::vector&lt;Edge *&gt; adjacency_list;
  </code></pre>
  
  <p>the program doesn't works, but I'm not sure that this is the error, is it right initialize a vector like I'm doing?</p>