title: Why use QVector(Qt) instead of std::vector
body: <p>I'm very new to C++ and Qt, but I'm very good at C#/Java.</p>
  
  <p>The point is I like cross-platform, but I'm confuse with Qt. Isn't <code>std::vector</code> already cross-platform, doesn't Qt provide an equivalent to a non-crossplatform thing?</p>
  
  <p>Also how are <code>File</code> and <code>QFile</code> different?</p>
  
  <p>A link would be nice, thanks :)</p>