QByteArray to QString to std::stringstream doesn't work - c++

Question

anyone know why
QString Lulu ( data ); //data is a QByteArry ( from a QNetworkrequest )
std::stringstream streamedJson ;
// QString Lulu ( data.data() );
qDebug()<< "Lulu:" << Lulu; // here it views the right string
streamedJson << Lulu.toStdString();
qDebug() << "streamedJson: "<< streamedJson ; // here it views 0x7fffc9d46568
doesn't works ?
why it dont view the String here ?
finally i would parse it and give the parsed string out
boost::property_tree::ptree propertyTree;
try
{
boost::property_tree::json_parser::read_json(streamedJson, propertyTree);
}
catch(boost::property_tree::json_parser::json_parser_error& ex)
{
qDebug() << "ex: "<< ex.what(); // this and Lulu views the same (unparsed) string
qDebug ("propertyree error");
}
at the moment it only views "propertyree error". but it should print the parsed String in my console

Answer 1

std::stringstream cannot be directly used with QDebug::operator<<. You can explicitly convert it to QString. For example,
qDebug() << "streamedJson: " << QString::fromStdString(streamedJson.str());
The streamedJson.str() returns an std::string, and then converted to QString using QString::fromStdString.
Your program prints 0x7fffc9d46568 probably because the streamedJson is converted to a qDebug-printable object implicitly. Or maybe there is an operator<< function somewhere in your program that takes std::stringstream as input.

Answer 2

Try initialization of the QString variable as explained below and try putting the value into a std::string variable before pushing it into the std::stringstream.
QString Lulu = QString(data);
std::stringstream streamedJson ;
std::string strLulu = Lulu.toStdString();
streamedJson << strLulu;
qDebug() << "streamedJson: "<< streamedJson;
Hope this helps.

Answer 3

Class QString has function std::string toStdString() const. Maybe you should use it this way:
streamedJson << Lulu.toStdString();
If it will not work you can try
streamedJson << Lulu.toStdString().c_str();
If it will not work too we would find another possible solution. Good luck!
EDIT:
I've read several documents and I guess I've solved your problem. Class std::stringstream has inner representation of string. In order to get std::string from this class you should use its function str():
http://www.cplusplus.com/reference/sstream/stringstream/str/
Then your code should be looking like this:
string myString = streamedJson.str();
std::cout << myString;
I believe it will work.