title: adding number to a QByteArray
body: <p>i have a <code>QbyteArray</code>  named <code>"B2"</code>,</p>
  
  <p>and i want to add  to this a 2byte number like <code>300</code>.</p>
  
  <p>but when i do that <code>mybyte.size()</code> become <code>3byte!!!!</code> </p>
  
  <p>my code is : </p>
  
  <p>i want to it become 2byte. </p>
  
  <pre><code>    QByteArray B2;
          short int myint;
          myint=300;
          B2.setNum(myint);
  qDebug()&lt;&lt;B2[0]&lt;&lt;B2.size();
  </code></pre>
  
  <p>and this is my output: </p>
  
  <pre><code>3 3 
  </code></pre>