title: QByteArray and its normal c++ equivalent
body: <p>I have a previous code written in QT. The output generated is very slow. 
  I have a very basic knowledge of QT. 
  I wish to know the of <code>QByteArray</code> object and <code>QChar</code> to normal c++ equivalent. </p>
  
  <p>The <code>Datapackage</code> class in Qt.</p>
  
  <pre><code>class Datapackage
  {
  public:
      Datapackage(QByteArray datas,int start);
      QVector&lt;double&gt; getX() const;
      QVector&lt;double&gt; getY() const;
  
  private:
      QVector&lt;QChar&gt; intensity;
      QVector&lt;double&gt;x;
      QVector&lt;double&gt;y;
      qint8 header[288];
  };
  </code></pre>
  
  <p>My tried normal c++ <code>Datapackage</code> class </p>
  
  <pre><code>class Datapackage
  {
  public:
      Datapackage( std::vector&lt;char&gt; datas , int start );
      std::vector&lt;double&gt; getX() const;
      std::vector&lt;double&gt; getY() const;
  
  private:
      std::vector&lt;char&gt; intensity;
      std::vector&lt;double&gt; x;
      std::vector&lt;double&gt; y;
     int8_t header[288];
  
  };
  </code></pre>
  
  <p>My results are absurd. I am doing the wrong conversion.
  Could you suggest a good way. The above class is not a complete code. I removed some data not to make the code too long. </p>