[SOLVED] Double or single quoting: compiler dependent?

sirop

Hallo.

I have a simple predefined string:

pSender->sendTextMessage(QString("{\"action\":\"auth\",\"status\":\"error\",\"data\": {\"id\":3,\"msg\":\"Unknown user or incorrect password.\"}}") );

As you might guess, it is about WebSocket programming.
The problem I have is that when I compile with msvc2013,
this message string is created and transmitted properly with all the double quotes at the right place:

{"action":"auth","status":"error","data": {"id":3,"msg":"Unknown user or incorrect password."}}

But when I compile with gcc version 4.9.1 (Ubuntu 4.9.1-16ubuntu6), I get this output
on the client side:

{ action: 'auth',status: 'error',data: {id:'3', msg:'Unknown user or incorrect password.'} }

As you see, the JSON tags have no quote signs at all and their values are single quoted
which is not JSON standard.

I read through http://stackoverflow.com/questions/21431633/does-g-meets-stdstring-c11-requirements. Do not know if I went astray with that...
But on the other hand side: such a simple thing as quoting a string should be compiler dependent?

So would updating to g++-5 solve the problem as this Stackoverflow link says:
The other answers were correct at the time, but as of nowadays, accordingly to the GCC 5.x Change Log, libstdc++ as shipped by gcc 5 is now fully C++11 conformant.

jsulm

This post is deleted!

jsulm

Just tried on Ubuntu with g++:

std::cout << QString("{\"action\":\"auth\",\"status\":\"error\",\"data\": {\"id\":3,\"msg\":\"Unknown user or incorrect password.\"}}").toStdString();

and got correct result.

sirop

@jsulm

Thanks for your reply.

Can you tell me please which version of g++ you used?
Was it 5.x ?

jsulm

g++ (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4

sirop

@jsulm
Thanks again.

But what would you see if you try:

qDebug () << QString("{\"action\":\"auth\",\"status\":\"error\",\"data\": {\"id\":3,\"msg\":\"Unknown user or incorrect password.\"}}"

jsulm

In this case I see:

"{\"action\":\"auth\",\"status\":\"error\",\"data\": {\"id\":3,\"msg\":\"Unknown user or incorrect password.\"}}"

sirop

@jsulm

Yes, seems to be something QWebSockets and compiler specific.
See http://code.woboq.org/qt5/qtwebsockets/src/websockets/qwebsocket_p.cpp.html#_ZN17QWebSocketPrivate15sendTextMessageERK7QString

qint64 QWebSocketPrivate::sendTextMessage(const QString &message)
{
       return doWriteFrames(message.toUtf8(), false);
}

And so on as doWriteFrames does coms char* conversion.

jsulm

toUtf8() returns a QByteArray, QByteArray::data() returns char*. if I do:

std::cout << QString("{\"action\":\"auth\",\"status\":\"error\",\"data\": {\"id\":3,\"msg\":\"Unknown user or incorrect password.\"}}").toUtf8().data();

I still get the correct result.
I don't think it is a compiler issue (why should compiler remove " or replace them with ' ?).
How do you print out the string?

sirop

@jsulm said:

std::cout << QString("{"action":"auth","status":"error","data": {"id":3,"msg":"Unknown user or incorrect password."}}").toUtf8().data();

I set up this simple app:

#include <QCoreApplication>
#include <iostream>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    std::cout << QString("{\"action\":\"auth\",\"status\":\"error\",\"data\":{\"id\":3,\"msg\":\"Unknown user or incorrect password.\"}}").toUtf8().constData();
    return a.exec();
}

This works as it should with mingw51_x64 and msvc2013_x64 on Windows.

But with gcc version 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2) no output is printed out at all,
although it compiles without errors.

So if it is not a compiler issue then it is a compiler installation issue.

sirop

As always complicated problems have unexpectedly simple solutions.
Due to restricted user privileges I did not see the old chat server process
started by a colleague of mine.

So we were testing the old version all the time where the quoting issue
had not been yet dealt with.