I'm working with a buffer and I'm trying to get a string from it, but isnt working...
Example:
*void myFunc(QDataStream& in)
{
quint8 v;
in >> v;
// Ok, I caught v value successfuly
QString s;
in >> s;
// Didnt work :<
}*
The string lenght is stored on 2 first bytes...
Thanks
If the string was not written as a QString, you need to read its length and content separately.
quint8 v;
in >> v;
quint16 length = 0;
in >> length;
// the string is probably utf8 or latin
QByteArray buffer(length, Qt::Uninitialized);
in.readRawData(buffer.data(), length);
QString string(buffer);
You might have to change the endianness of the QDataStream with QDataStream::setByteOrder before reading the 16-bit length.
We should really see the writing code and how you create the QDataStream. I tried with the following sample, and in this case your function works very well:
#include <QCoreApplication>
#include <QDebug>
#include <QDataStream>
#include <QBuffer>
void myFunc(QDataStream& in)
{
quint8 v;
in >> v;
qDebug() << v;
// Ok, I caught v value successfuly
QString s;
in >> s;
qDebug() << s;
// Didnt work :<
}
int main(int argc, char ** argv) {
QCoreApplication a(argc, argv);
QBuffer buffer;
buffer.open(QBuffer::ReadWrite);
// write test data into the buffer
QDataStream out(&buffer);
quint8 ival = 42;
QString sval = "Qt";
out << ival;
out << sval;
// read back data
buffer.seek(0);
myFunc(out);
return a.exec();
}
Output when executed:
$ ./App
42
"Qt"
Related
Code:
using ColumnIndexVector = std::vector<int>;
using ByteVector = std::vector<BYTE>;
void CCreateReportDlg::GetColumnIndexesToExclude()
{
const CString strSection = theApp.GetActiveScheduleSection(_T("Options"));
ByteVector vData = theApp.GetProfileVector(strSection, _T("AssignStatesEx"));
ColumnIndexVector vTemp(vData.begin(), vData.end()); // This converts BYTE to int
m_vColumnIndexesToExclude = vTemp;
}
Is there any way to avoid the requirement for vTemp without manually iterating vData and casting from BYTE to int?
Yes, just use assign(). IDK if you need to use clear() as well, but probably not. Just step through the runtime code the first time to know.
m_vColumnIndexesToExclude.assign(vData.begin(), vData.end());
Here's a test program:
#include <windows.h>
#include <iostream>
#include <vector>
using namespace std;
using ColumnIndexVector = std::vector<int>;
using ByteVector = std::vector<BYTE>;
int main(int argc, char* argv[])
{
cout << "Test" << endl;
ByteVector bytes = {'A', 'B', 'C', 'D'};
ColumnIndexVector colVector;
for ( auto _val: bytes)
{
cout << _val << endl;
}
colVector.assign(bytes.begin(), bytes.end());
for ( auto _val : colVector)
{
cout << _val << endl;
}
return 0;
}
If used QTextStream console(stdout) - all work just fine, but if I wrote custom IODevice, after qInstallMsgHandler() no text in console
main.cpp
#include "remoteconsole.h"
#include <QCoreApplication>
#include <QDateTime>
#include <QTimer>
QTextStream *out;
void logOutput(QtMsgType type, const char *msg)
{
QString debugdate = QDateTime::currentDateTime().toString("yyyy.MM.dd hh:mm:ss.zzz");
*out << debugdate << " " << type << msg << endl;
}
int main(int argc, char *argv[])
{
int i;
QCoreApplication a(argc, argv);
RemoteConsole * remote = new RemoteConsole(&a);
QTextStream console((QIODevice *)remote);
out = &console;
qDebug() << "start qInstallMsgHandler";
qInstallMsgHandler(logOutput);
qDebug() << "end qInstallMsgHandler"<<endl;
for(i=0;i<10;i++){
qDebug() << i<<endl;
}
QTimer *timer = new QTimer();
a.connect(timer, SIGNAL(timeout()), &a, SLOT(quit()));
timer->start(5000);
a.exec();
return 0;
}
my IODevice implementation in file remoteconsole.h .cpp
#ifndef REMOTECONSOLE_H
#define REMOTECONSOLE_H
#include <QIODevice>
#include <QDebug>
class RemoteConsole: public QIODevice
{
Q_OBJECT
public:
RemoteConsole(QObject *parent);
~RemoteConsole();
private:
Q_DISABLE_COPY(RemoteConsole)
protected:
qint64 readData(char* data, qint64 maxSize);
qint64 writeData(const char* data, qint64 maxSize);
};
#endif // REMOTECONSOLE_H
#include "remoteconsole.h"
RemoteConsole::RemoteConsole(QObject* parent=0) :
QIODevice(parent)
{
}
RemoteConsole::~RemoteConsole(){}
qint64 RemoteConsole::readData(char *data, qint64 maxlen){
qDebug() << data <<endl;
return maxlen;
}
qint64 RemoteConsole::writeData(const char *data, qint64 len){
printf("writeData");
qDebug() << data <<endl;
return len;
}
In future I want to expand this code with QTCPServer, that send debug outputs to client connected to the device by telnet or nc.
You don't get any text in console after qInstallMsgHandler call because you send all debug data into your RemoteConsole object.
Also you've got some other problems in your code.
You should call QIODevice::open before you can operate on that device.
In the RemoteConsole::writeData function you will have an infinite loop because you use qDebug() there. qDebug() will call logOutput which will call RemoteConsole::writeData again.
I have a rellly long process that produces about 700 Mb of a txt log output file. This is very hard to manage. So I want to divide the output in multiple smaller log files. This is what my main.cpp looks like
#include <QtGui/QApplication>
#include "mineedit.h"
#include "logoutput.h"
#include <iostream>
void messageHandling(QtMsgType type, const char *msg){
if (ERRORLOGGER.isEmpty()){
ERRORLOGGER = DEFERRORLOGGER;
}
std::cout << "In Message Handling" << std::endl;
std::cout << "Writing to file" << ERRORLOGGER.toStdString() << std::endl;
QFile file(ERRORLOGGER);
file.open(QFile::Append);
QTextStream stream(&file);
switch (type) {
case QtDebugMsg:
stream << msg << "\n";
file.close();
break;
case QtWarningMsg:
stream << "WARNING: " << msg << "\n";
file.close();
break;
case QtCriticalMsg:
stream << "CRITICAL: " << msg << "\n";
file.close();
break;
case QtFatalMsg:
stream << "FATAL: " << msg << "\n";
file.close();
abort();
}
}
int main(int argc, char *argv[])
{
ERRORLOGGER = DEFERRORLOGGER;
qInstallMsgHandler(messageHandling);
QApplication a(argc, argv);
MineEdit w;
w.show();
return a.exec();
}
[/CODE]
And my logoutput.h is like
#ifndef LOGOUTPUT_H
#define LOGOUTPUT_H
#include <QString>
//----------------------------For outputting an error file------------------------------
#define DEFERRORLOGGER "/home/aarelovich/Documents/log.err"
#define FOLDER_OUTPUT_LOG "./home/aarelovich/Documents"
extern QString ERRORLOGGER;
#endif // LOGOUTPUT_H
Now in a part of my code I do:
ERRORLOGGER = name_of_current_log_file.
However I get the following compilation errors:
obj/main.o: In function messageHandling(QtMsgType, char const*)':
/home/aarelovich/Dropbox/MineSim/main.cpp:8: undefined reference toERRORLOGGER'
/home/aarelovich/Dropbox/MineSim/main.cpp:9: undefined reference to ERRORLOGGER'
/home/aarelovich/Dropbox/MineSim/main.cpp:13: undefined reference toERRORLOGGER'
/home/aarelovich/Dropbox/MineSim/main.cpp:15: undefined reference to ERRORLOGGER'
obj/main.o: In functionmain':
/home/aarelovich/Dropbox/MineSim/main.cpp:40: undefined reference to ERRORLOGGER'
obj/mineedit.o:/home/aarelovich/Dropbox/MineSim/mineedit.cpp:101: more undefined references toERRORLOGGER' follow
collect2: ld returned 1 exit status
Can anyone please tell me what am I doing wrong? Or how I can dynamically change the output file in which I create my application log?
Thanks for any help
Your problem is probably related to extern variable.
Here is an example of how to use extern keyword in c++.
Beware that C++ and C have differences with extern keyword when linking.
Basicall what you need to do is
global.cpp:
// declaration of g_nValue
int g_nValue = 5;
main.cpp:
// extern tells the compiler this variable is declared elsewhere
extern int g_nValue;
int main()
{
g_nValue = 7;
return 0;
}
In your example if you use extern QString ERRORLOGGER; in logoutput.h,
this variable needs to be declared in another cpp just as explained in the link.
I hope this helps
I am trying to serialize a QHash object and store it in a QByteArray (to be sent using QUDPSocket or QTCPSocket).
My current attempt looks like this:
// main.cpp
#include <QtCore/QCoreApplication>
#include <QHash>
#include <QVariant>
#include <QDebug>
int main(int argc, char *argv[])
{
QHash<QString,QVariant> hash;
hash.insert("Key1",1);
hash.insert("Key2","thing2");
QByteArray ba;
QDataStream ds(&ba, QIODevice::WriteOnly);
ds << hash;
qDebug() << ds;
}
When this runs I get this out of qDebug():
QIODevice::read: WriteOnly device
QIODevice::read: WriteOnly device
QIODevice::read: WriteOnly device
QVariant(, )
The documentation says that this should write to the byte array, but obviously that isn't happening here. What am I doing wrong?
Qt 4.7.1 on OS-X
Thanks!
-J
The reason it is failing is because it is trying to read from a write-only stream. The sequence is:
qDebug() << ds;
--> QVariant::QVariant(QDataStream &s)
--> QDataStream& operator>>(QDataStream &s, QVariant &p)
--> void QVariant::load(QDataStream &s)
That last method (and some more downstream) try to read from the data stream to convert its contents into a QVariant for display in qDebug. In other words, your actual code is fine; the debugging check is causing the failure.
You could check the contents of the byte array with something like:
qDebug() << ba.length() << ba.toHex();
You can Implement you program like this code:
QHash<QString,QVariant> options;
options["string"] = "my string";
options["bool"] = true;
QByteArray ar;
//Serializing
QDataStream out(&ar,QIODevice::WriteOnly); // write the data
out << options;
//setting a new value
options["string"] = "new string";
//Deserializing
// read the data serialized from the file
QDataStream in(&ar,QIODevice::ReadOnly);
in >> options;
qDebug() << "value: " << options.value("string");
ref
I want to save a QList<int> to my QSettings without looping through it.
I know that I could use writeArray() and a loop to save all items or to write the QList to a QByteArray and save this but then it is not human readable in my INI file..
Currently I am using the following to transform my QList<int> to QList<QVariant>:
QList<QVariant> variantList;
//Temp is the QList<int>
for (int i = 0; i < temp.size(); i++)
variantList.append(temp.at(i));
And to save this QList<Variant> to my Settings I use the following code:
QVariant list;
list.setValue(variantList);
//saveSession is my QSettings object
saveSession.setValue("MyList", list);
The QList is correctly saved to my INI file as I can see (comma seperated list of my ints)
But the function crashes on exit.
I already tried to use a pointer to my QSettings object instead but then it crashes on deleting the pointer ..
QSettings::setValue() needs QVariant as a second parameter. To pass QList as QVariant, you have to declare it as a Qt meta type. Here's the code snippet that demonstrates how to register a type as meta type:
#include <QCoreApplication>
#include <QDebug>
#include <QMetaType>
#include <QSettings>
#include <QVariant>
Q_DECLARE_METATYPE(QList<int>)
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
qRegisterMetaTypeStreamOperators<QList<int> >("QList<int>");
QList<int> myList;
myList.append(1);
myList.append(2);
myList.append(3);
QSettings settings("Moose Soft", "Facturo-Pro");
settings.setValue("foo", QVariant::fromValue(myList));
QList<int> myList2 = settings.value("foo").value<QList<int> >();
qDebug() << myList2;
return 0;
}
You might have to register QList as a meta-type of its own for it to work. This is a good starting point to read up on meta-types in Qt: http://qt.nokia.com/doc/4.6/qmetatype.html#details .
I was also struggling with this ... and I believe I now have a decent solution.
I hope this saves someone the trouble, it caused me.
#include <QCoreApplication>
#include <QSettings>
#include <QList>
#include <QDataStream>
#include <QVariant>
#include <QVariantList>
#include <QDebug>
#include <deque>
template <class T> static QVariant toVariant(const QList<T> &list)
{
QVariantList variantList;
variantList.reserve(list.size());
for (const auto& v : list)
{
variantList.append(v);
}
return variantList;
}
template <class T> static QList<T> toList(const QVariant &qv)
{
QList <T> dataList;
foreach(QVariant v, qv.value<QVariantList>()) {
dataList << v.value<T>();
}
return dataList;
}
void Gen()
{
QList<QString> data {"hello", "world","how", "are", "you"};
QList<int> ages {10,20,30,40};
QSettings setup("stuff.ini", QSettings::IniFormat);
setup.beginWriteArray("rules");
for (int groups=0;groups<3;groups++)
{
setup.setArrayIndex(groups);
setup.setValue("rule",QString("Rule-%1").arg(groups));
setup.setValue("data", toVariant (data));
setup.setValue("ages", toVariant (ages));
}
setup.endArray();
setup.sync();
}
void Read()
{
QSettings setupR("stuff.ini", QSettings::IniFormat);
int rule_count = setupR.beginReadArray("rules");
for (int groups=0;groups<rule_count;groups++)
{
setupR.setArrayIndex(groups);
QString nameRead = setupR.value("rule").toString();
QList<QString> dataRead = toList<QString>(setupR.value("data"));
qDebug() << "Rule " << groups;
qDebug() << "Rule Read" << nameRead;
qDebug() << "Data Read2" << dataRead;
}
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
// Write
Gen();
// Read
Read();
exit(0);
//return a.exec();
}
You should end up with an INI file which looks like this ...
[rules]
1\ages=10, 20, 30, 40
1\data=hello, world, how, are, you
1\rule=Rule-0
2\ages=10, 20, 30, 40
2\data=hello, world, how, are, you
2\rule=Rule-1
3\ages=10, 20, 30, 40
3\data=hello, world, how, are, you
3\rule=Rule-2
size=3
The nice thing here is you can edit this outside of QT (Just be careful) ...