How to output QList to standard console ?

Anonymous_Banned275

SOLVED

Here are final tests and they all work fine.
There is a small issue in debugging these "prints" they get "out of sequence " and if the test "exit" is in wrong place code get missed.

Thanks for all the wonderful support received in resolving this .

    cout << "***************************************function " << __FUNCTION__ << endl;
    qDebug() << "DEBUG  message " << BT_string_list.size()<< ", says: " << BT_string_list.at(0).name();
    qDebug() << "DEBUG  message " << BT_string_list.size()<< ", says: " << BT_string_list.at(1).name();
    cout << "cout test #1 " << BT_string_list.at(0).name().toStdString() << endl;
    cout <<"cout test #2 " << BT_string_list.at(0).name().toLocal8Bit().constData() << endl;

I am using QList with template QBluetoothHostInfo.
to retrieve (scan) for local bluetooth devices. It returns correct count of devices, however, I cannot figure out how to retrieve / print the actual names of the devices to console.

The missing piece is relation between QBluetoothHostInfo and QString .

I can retrieve single bluetooth device name correctly using QStringList , but need to use QBluetoothHostInfo. to retrieve them all.

I also like to use standard std::cout to output QString to local console for debugging purposes.
cout << QString << endl; does not work

Here is the "work in progress" code

 // buidl a list of local BT devices
   QList<QBluetoothHostInfo> BT_string_list;        // info , not local
   BT_string_list << scan_agent->BTLocalDeviceInfo.allDevices(); // all BT devies
   if(BT_string_list.size())
   {
#ifdef DEBUG
       cout << endl;
    cout << "TRACE Current marker  " << __FUNCTION__ << endl;
    cout << "BT_string_list.size() OK           @line  list size  " <<( BT_string_list.size()) << "  " << __LINE__ << endl;
   // cout << "function " << __FUNCTION__ << endl;
#endif
   }
   else
   {
#ifdef DEBUG
    cout << "TRACE Current marker  " << __FUNCTION__ << endl;
    cout << " BT_string_list.size() FAILED   @line " << BT_string_list.size() << __LINE__ << endl;
    cout << "function " << __FUNCTION__ << endl;
#endif
   }
   cout << BT_string_list.size() << endl;

Chrisw01

Have you tried something like this?

for(int loop1 = 0; loop1 < BT_string_list.size(); loop1++) {
    cout << BT_string_list.at(loop1);
}

Pablo J. Rogina

@AnneRanch said in How to output QList to standard console ?:

I cannot figure out how to retrieve / print the actual names of the devices to console.

What about QBluetoothHostInfo::name():

Returns the user visible name of the host info object.

Anonymous_Banned275

@Chrisw01

That is the problem - I get this error
and I do not know how to implement the correct operator <<
because QBluetoothHostInfo in not a QString .

/media/z/DOC_COPY_LABEL/Projects /QT_TEST/TEST_Splitter/application_Form_1/application/mainwindow_form.cpp:97: error: no match for 'operator<<' (operand types are 'std::ostream {aka std::basic_ostream<char>}' and 'const QBluetoothHostInfo')
cout << BT_string_list.at(loop1);
^

JonB

@AnneRanch
The object you have there is a whole QBluetoothHostInfo. The error message tells you the << operator hasn't been written to cope with that. You can't convert a whole QBluetoothHostInfo to a QString. @Pablo-J-Rogina is suggesting you output a QBluetoothHostInfo::name(), just the name of it. So presumably

cout << BT_string_list.at(loop1).name();

Chrisw01

@AnneRanch My bad, try BT_string_list.at(loop1).name();

Anonymous_Banned275

@JonB

Sorry, still no good.

Here is the code

  cout << BT_string_list.at(loop1).name();

won't even compile

  qDebug ("DEBUG  message %d, says: %s",
          BT_string_list.size(),BT_string_list.at(loop1).name());

runs but "prints" garbage

And error
/media/z/DOC_COPY_LABEL/Projects /QT_TEST/TEST_Splitter/application_Form_1/application/mainwindow_form.cpp:134: error: no match for 'operator<<' (operand types are 'std::ostream {aka std::basic_ostream<char>}' and 'QString')
cout << BT_string_list.at(loop1).name();
^

Same issue
the BT_string_list.at(loop returns "item" ( per doc ) and I have no clue what is "item" .

The .name() , assuming it is a one of the items should return QString .
Neither qDebug or "loop ..." see a QString - that is the issue.

In simple terms - I need to convert whatever type ins "item" to QString to be able to send it to console. I am open to options, but woudl like to stick with C++ std::cout . This QString intead of C++ "String" is making things unnecessary complicated to code in Qt.

Pablo J. Rogina

@AnneRanch said in How to output QList to standard console ?:

the BT_string_list.at(loop returns "item" ( per doc ) and I have no clue what is "item" .

Wow, it's something you defined yourself...

QList<QBluetoothHostInfo> BT_string_list;

so "item" will be an object of class ___________ (please fill in the blanks)

J.Hilk

@AnneRanch
std::cout knows nothing of QString, by default at least, but it can print std::strings

therefore:

cout << BT_string_list.at(loop1).name().toStdString();

VRonin

https://doc.qt.io/qt-5/qtglobal.html#qPrintable

JonB

@AnneRanch said in How to output QList to standard console ?:

qDebug ("DEBUG message %d, says: %s", BT_string_list.size(),BT_string_list.at(loop1).name());

runs but "prints" garbage

That's because you have not looked up the syntax or examples of qDebug(). Always use the (excellent) documentation! Look at https://doc.qt.io/qt-5/qdebug.html. See how it always uses the << operator? So

qDebug() << "DEBUG  message " << BT_string_list.size() << ", says: " << BT_string_list.at(loop1).name();

Anonymous_Banned275

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