QDataStream and QByteArray issue

[sepehr]

hey guys,
I'm trying to save a binary data as string in a QByteArray and for testing I used a simple text as my data and did the following:

QByteArray str2Store;      
  QDataStream out(&str2Store,QIODevice::WriteOnly);  
  out<<"salam";
  qDebug()<<str2Store;

QByteArray str2Store;      
  QDataStream out(&str2Store,QIODevice::WriteOnly);  
  out<<"salam";
  qDebug()<<str2Store;

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now I should be expecting the string "salam" in str2Store variable but only a " is echod by qDebug,ofcourse str2Store.length() returns 10,why is the length 10? and why str2Store is not filled with the the string "salam"?