Reading QByteArray from QDataStream Qt3.3

[high_flyer]

Hi,

I am overloading the operator>>() and operator<<() for QDataStream to serialize my own data blocks.
For writing in to binary file:

QDataStream & operator<<( QDataStream &s, AtmosBBlock &data)
{
 QByteArray b_data;
 b_data.resize(sizeof(data));
 memcpy(b_data.begin(),&data,sizeof(data));
  s<<b_data;
 return s;
}

QDataStream & operator<<( QDataStream &s, AtmosBBlock &data)
{
 QByteArray b_data;
 b_data.resize(sizeof(data));
 memcpy(b_data.begin(),&data,sizeof(data));
  s<<b_data;
 return s;
}

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For reading from binary file:

QDataStream & operator>>( QDataStream &s, AtmosBBlock &data)
{
  QByteArray b_data;
  b_data.resize(sizeof(data));
  s>>b_data;
  memcpy(&data,b_data.begin(),sizeof(data));
  return s;
}

QDataStream & operator>>( QDataStream &s, AtmosBBlock &data)
{
  QByteArray b_data;
  b_data.resize(sizeof(data));
  s>>b_data;
  memcpy(&data,b_data.begin(),sizeof(data));
  return s;
}

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The problem is, that s>>b_data is resulting in a 0 sized QByteArray, and I don't understand why.
To check if the problem is in the written file I did the following:

QDataStream & operator>>( QDataStream &s, AtmosBBlock &data)
{
  QByteArray b_data;
  b_data.resize(sizeof(data));
  s.readRawBytes((char*)&b_data,sizeof(b_data));
  memcpy(&data,b_data.begin(),sizeof(data));
  return s;
}

QDataStream & operator>>( QDataStream &s, AtmosBBlock &data)
{
  QByteArray b_data;
  b_data.resize(sizeof(data));
  s.readRawBytes((char*)&b_data,sizeof(b_data));
  memcpy(&data,b_data.begin(),sizeof(data));
  return s;
}

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This reads the file correctly with the previously written data.

Any idea why s>>b_data returns a 0 sized QByteArray?

Thanks in adavance.