title: can not understanding declaration of constructor of wrapper class
body: <p>Below is a wrapper class I found in the stackoverflow.</p>
  
  <pre><code>class int_ptr_wrapper
  {
  public:
      int_ptr_wrapper(int value = 0) :
      mInt(new int(value))
      {}
  
      // note! needs copy-constructor and copy-assignment operator!
  
      ~int_ptr_wrapper()
      {
          delete mInt;
      }
  
  private:
      int* mInt;
  };
  </code></pre>
  
  <p>I could not understand the meaning of declaration:</p>
  
  <pre><code>    int_ptr_wrapper(int value = 0) :
      mInt(new int(value))
      {}
  </code></pre>
  
  <p>Can you explain the meaning of this declaration in details?</p>