How to output QList to standard console ?
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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 workHere 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;@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.
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Have you tried something like this?
for(int loop1 = 0; loop1 < BT_string_list.size(); loop1++) { cout << BT_string_list.at(loop1); }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);
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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);
^@AnneRanch
The object you have there is a wholeQBluetoothHostInfo. The error message tells you the<<operator hasn't been written to cope with that. You can't convert a wholeQBluetoothHostInfoto aQString. @Pablo-J-Rogina is suggesting you output aQBluetoothHostInfo::name(), just the name of it. So presumablycout << BT_string_list.at(loop1).name(); -
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);
^ -
@AnneRanch
The object you have there is a wholeQBluetoothHostInfo. The error message tells you the<<operator hasn't been written to cope with that. You can't convert a wholeQBluetoothHostInfoto aQString. @Pablo-J-Rogina is suggesting you output aQBluetoothHostInfo::name(), just the name of it. So presumablycout << BT_string_list.at(loop1).name();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.
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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.
@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)
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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.
@AnneRanch
std::cout knows nothing of QString, by default at least, but it can print std::stringstherefore:
cout << BT_string_list.at(loop1).name().toStdString(); -
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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.
@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? SoqDebug() << "DEBUG message " << BT_string_list.size() << ", says: " << BT_string_list.at(loop1).name(); -
@AnneRanch
std::cout knows nothing of QString, by default at least, but it can print std::stringstherefore:
cout << BT_string_list.at(loop1).name().toStdString();This post is deleted!
