title: Access to specific private members from specific class
body: <p>I have a class</p>
  
  <pre><code>class A
  {
  .....
  private:
      int mem1;
      int mem2;
  }
  </code></pre>
  
  <p>I have another class B which need to access only to mem1.</p>
  
  <pre><code>class B
  {
    ....
  }
  </code></pre>
  
  <p>How can I access private member mem1 from only from class B? I don't want to use friend. This means access to all private members.</p>