title: What is mutable const?
body: <p>I didn't find any topics related to <code>mutable const</code> on SO.  I have reduced code to minimal working code (on visual studio). If we uncomment <code>//*data = 11;</code>, the compiler complains about const-ness. I wonder how <code>mutable const</code> works.</p>
  
  <pre><code>class A
  {
  public:
  
      void func(int &amp; a) const
      {
          pdata = &amp;a;
          //*pdata = 11;
      }
  
      mutable const int * pdata;
  };
  
  int main()
  {
      const A obj;
  
      int a = 10;
      obj.func(a);
  }
  </code></pre>