title: initialize STL map with constructor
body: <p>I have a class with STL map and another class as member variables.</p>
  
  <p>Here is my class definition:</p>
  
  <pre><code>class demo
  {
      map&lt;int, map&lt;int, string&gt; &gt; mymap;
  
      class temp
      {
          int a, b;
      }
  
      map&lt;string, pair&lt;string, temp*&gt; &gt; mymap1;
  
      demo();
      ~demo();
  }
  </code></pre>
  
  <p>How do I initialize <code>mymap</code> and <code>mymap1</code> to <code>NULL</code> using constructor. I also want to free up memory used by <code>temp*</code> using destructor. How do I do that?</p>