Cannot Give a Parameter To QT connect Function - c++

Question

I implemented reading bytes at a serial communication in a Qt project(5.5) in Visual Studio 2013.
My code is here:
main.cpp
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
//QCoreApplication coreApplication(argc, argv);
int argumentCount = QCoreApplication::arguments().size();
QStringList argumentList = QCoreApplication::arguments();
QTextStream standardOutput(stdout);
if (argumentCount == 1) {
standardOutput << QObject::tr("Usage: %1 <serialportname> [baudrate]").arg(argumentList.first()) << endl;
return 1;
}
QSerialPort serialPort;
QString serialPortName = argumentList.at(1);
serialPort.setPortName(serialPortName);
int serialPortBaudRate = (argumentCount > 2) ? argumentList.at(2).toInt() : QSerialPort::Baud9600;
serialPort.setBaudRate(serialPortBaudRate);
if (!serialPort.open(QIODevice::ReadOnly)) {
standardOutput << QObject::tr("Failed to open port %1, error: %2").arg(serialPortName).arg(serialPort.errorString()) << endl;
return 1;
}
Camera cam2;
//cam2.showCamera();
cam2.showCamera();
cam2.showFullScreen();
QByteArray abc;
SerialPortReader serialPortReader(&serialPort,abc);
//return coreApplication.exec();
return app.exec();
};
serialportreader.cpp
#include "serialportreader.h"
#include <QCoreApplication>
QT_USE_NAMESPACE
SerialPortReader::SerialPortReader(QSerialPort *serialPort, QByteArray abc, QObject *parent)
: QObject(parent)
, m_serialPort(serialPort)
, m_standardOutput(stdout)
{
connect(m_serialPort, &QSerialPort::readyRead, this, &SerialPortReader::handleReadyRead);
}
SerialPortReader::~SerialPortReader()
{
}
void SerialPortReader::handleReadyRead()
{
m_readData.append(m_serialPort->readAll());
if (!m_readData.isEmpty()) {
m_standardOutput << m_readData << endl;
m_readData.clear();
}
}
This code works successfully. I would like to set the contents of m_readData array to abc array so that I can evaluate the message in main scope. In order to implement this, I gave abc array to handleReadyRead function as a parameter. However, it gives an error.The code is here:
SerialPortReader::SerialPortReader(QSerialPort *serialPort, QByteArray abc, QObject *parent)
: QObject(parent)
, m_serialPort(serialPort)
, m_standardOutput(stdout)
{
connect(m_serialPort, &QSerialPort::readyRead, this, &SerialPortReader::handleReadyRead(abc));
}
SerialPortReader::~SerialPortReader()
{
}
void SerialPortReader::handleReadyRead(QByteArray abc)
{
m_readData.append(m_serialPort->readAll());
if (!m_readData.isEmpty()) {
m_standardOutput << m_readData << endl;
m_readData.clear();
}
}
Error:
serialportreader.cpp(45): error C2102: '&' requires l-value
line45:
connect(m_serialPort, &QSerialPort::readyRead, this, &SerialPortReader::handleReadyRead(abc));

Answer 1

You can't pass the local variable to the slot this way, but what you are trying to do doesn't even require it. You could just store abc to a member variable in the constructor, and use it in the slot. BUT: you have to change it to a reference, otherwise the call to the constructor copies the array, so the original one in your main function is unaffected.
You could also just implement this array as a member variable of your SerialReader, and provide a getter function, so that the main function (or whoever is the consumer of the data) can just pull this data from the reader instance.