title: What is std::vector::front() used for?
body: <p>Sorry if this has been asked before, but I am wondering what the use of <code>std::vector::front()</code> is.</p>
  
  <p>Is there a reason to use e.g. <code>myvector.front()</code> rather than <code>myvector[0]</code> or <code>myvector.at(0)</code>?</p>