Invalid operands to binary expresion

arsinte_andrei

this is the error when I'm trying to compile this... Why do I get it?? What do I do wrong?

the header file

#ifndef ATPDATATYPES_H
#define ATPDATATYPES_H

#include <QMap>
#include <QString>
#include <QDataStream>

struct atpMessage {
//		atpMessage() {} //TODO atpMessage
		QString userId;
		QString userPassword;
		QString device;
		QString module;
		QList<QMap<QString, QString>> tblData;
};

QDataStream &operator<<(QDataStream &out, const atpMessage &mesaj) {
	out << mesaj.userId << mesaj.userPassword << mesaj.device << mesaj.module << mesaj.tblData;
	return out;
}

QDataStream &operator>>(QDataStream &in, atpMessage &mesaj) {

	in >> mesaj.userId >>  mesaj.userPassword >> mesaj.device >> mesaj.module >> mesaj.tblData;
//	movie.id = (int)id;
//	movie.releaseDate = date;
	return in;
}


#endif // ATPDATATYPES_H

somewhere in the program that is including the header file

QMap<QString, QString> testMap1;
	atpTcpMesaj.device = "Raspberry Pi";
	atpTcpMesaj.module = "AlarmClock";
	atpTcpMesaj.userId = "andrei";
	atpTcpMesaj.userPassword = "parola";
	atpTcpMesaj.tblData.append(testMap1);

	qDebug() << atpTcpMesaj; // that is the line that give the error....  Invalid operands to binary expresion

/////
atpwidgetalarmclock.cpp:28: error: no match for ‘operator<<’ (operand types are ‘QDebug’ and ‘atpMessage’)
  qDebug() << atpTcpMesaj;

what it can be?? how to make my struct qDebug-able??

Kent-Dorfman

add a text format method to your atpMessage class, that returns a QString. QDebug won't know how to output adhoc classes. You need to provide the formatted string containing the relevant information about the object.

jsulm

@arsinte_andrei See https://doc.qt.io/qt-5/qdebug.html
"Writing Custom Types to a Stream" chapter.
You need to overload operator<<

arsinte_andrei

@jsulm if you look carefully this is what I've done in my opinion... but how to do it properly??

QDataStream &operator<<(QDataStream &out, const atpMessage &mesaj)

this is for the << operator!?!?

arsinte_andrei

@Kent-Dorfman if I return everything in QString then when I will use the operator << it won't work - and I need it to work in order to be able to send it as a stream over a TCP network

SGaist

Hi,

You implemented the QDataStream operator, what @jsulm wrote (that can be found in the documentation he linked) is that you have to implement the QDebug stream operator for your class.

arsinte_andrei

@SGaist & @jsulm

Many thanks... after looking a bit more in depth I've just understood how the things have to be done...

QDebug operator<<(QDebug debug, const atpMessage &mesaj) {
	QDebugStateSaver saver(debug);
	debug.nospace() << '(' << mesaj.userId << ", " << mesaj.userPassword << ", " << mesaj.device << ", " << mesaj.module << ", " << mesaj.tblData << ')';
	return debug;
}

that solved my problem...
Many thanks...

Kent-Dorfman

@arsinte_andrei said in Invalid operands to binary expresion:

f I return everything in QString then when I will use the operator << it won't work - and I need it to work in order to be able to send it as a stream over a TCP network

you misunderstand.

If you write a QString atpMessage::toString() {} method then qdebug << message.toString() will work, or, as @jsulm wrote you can overload the operator<<() for your class and QDebug will be able to handle it natively. Either will work, but I prefer my classes to use toString() as I don't like overloading << for types other than where the target is std::ostream...I know...I know...very java-esque.

Kent-Dorfman

@arsinte_andrei said in Invalid operands to binary expresion:

Many thanks... after looking a bit more in depth I've just understood how the things have to be done...

incidentally, if you go with overloading << then by all mean, pass QDebug by reference!

arsinte_andrei

@Kent-Dorfman I've understood your point but unfortunately for me, to have a function that will return strings will be un proper and also not a Qt style... I work with Qt so I want to do it Qt like... In Qt, if you have a type .toString then you will find also .fromString (or number in case of QString). Thanks to anyway... I've sorted it out ..