title: Static member functions
body: <p>After reading sbi and Eli Bendersky's answers in <a href="https://softwareengineering.stackexchange.com/questions/37550/c-calling-non-member-functions-with-the-same-syntax-of-member-ones">this question</a> I started to wondering what static member functions are for.</p>
  
  <p>A class' friend free function shouldn't be able to do <strong>anything</strong> a static member function can do? If so, why/when should I prefer a static member function to a friend free one?</p>