Regarding QProcess:: Not able to read data from the console

VRonin

yes, this is because you have myProcess as a member of your class, remove it from the members and just leave it as a local variable as I did in my code snippet:

QProcess* myProcess = new QProcess(this);

instead of:

myProcess = new QProcess;

Naveen_D

@VRonin ya its the same code

#include "ProcessWidget.h"

ProcessWidget::ProcessWidget(QWidget *parent)
    : QWidget(parent)
{
    m_btn= new QPushButton("click here",this);
    connect(m_btn,SIGNAL(clicked()),this,SLOT(vStartProcess()));
}

void ProcessWidget::vStartProcess()
{
    const QString program = QStringLiteral("/home/ubuntu/Documents/Sample_Examples_Qt_Qml/VoiceRecognition/VoiceRecognition");
    myProcess = new QProcess(this);
    connect(myProcess,&QProcess::readyReadStandardOutput,[myProcess]()->void{
            qDebug()<<"Output: "<< myProcess->readAllStandardOutput();
        });
    connect(myProcess,&QProcess::finished,myProcess,&QProcess::deleteLater);
    myProcess->start(program);
//    myProcess->waitForFinished(3000);
//    QString output(myProcess->readAll());
//    qDebug()<<"Output>>>>"<<output<<endl;
}

for this code i am getting that errors.

Naveen_D

@VRonin ya got that....but now i am getting no matching function call for the second connect statement...

VRonin

@Naveen_D said in Regarding QProcess:: Not able to read data from the console:

ya its the same code

No, as mentioned above you are using a member of the class while you should use a local variable

now i am getting no matching function call for the second connect statement

could you post the error output?

Naveen_D

@VRonin ya i came to know about the local variable.
the error is...
/home/ubuntu/Documents/Sample_Examples_Qt_Qml/ProcessTest/ProcessWidget.cpp:18: error: no matching function for call to 'ProcessWidget::connect(QProcess*&, <unresolved overloaded function type>, QProcess*&, void (QObject::*)())'
connect(myProcess,&QProcess::finished,myProcess,&QProcess::deleteLater);
^

VRonin

I did not realise finished is overloaded:

connect(myProcess,static_cast<void (QProcess::*)(int , QProcess::ExitStatus)>(&QProcess::finished),myProcess,&QProcess::deleteLater);

or

connect(myProcess,SIGNAL(finished()),myProcess,SLOT(deleteLater()));

Naveen_D

@VRonin said in Regarding QProcess:: Not able to read data from the console:

connect(myProcess,SIGNAL(finished()),myProcess,SLOT(deleteLater()));

i used this connect statement...after this the prgm builds without any issues but i am not getting any output in the console...

VRonin

as @m-sue suggested connect the standard error too:

connect(myProcess,&QProcess::readyReadStandardError,[myProcess]()->void{
        qDebug()<<"Output: "<< myProcess->readAllStandardError();
    });

Naveen_D

@VRonin said in Regarding QProcess:: Not able to read data from the console:

connect(myProcess,&QProcess::readyReadStandardError,myProcess->void{
qDebug()<<"Output: "<< myProcess->readAllStandardError();
});

yes...got the output
thanks. one more doubt after getting the output, when i close my application i get the following in my console..
QProcess: Destroyed while process ("/home/ubuntu/Documents/Sample_Examples_Qt_Qml/VoiceRecognition/VoiceRecognition") is still running.
is there any other way to end the process ??

Flotisable

@Naveen_D
I think you can connect ProcessWidget's destroyed signal to myProcess's close or kill slot

VRonin

remove the parent:
new QProcess(this); should become new QProcess; and then add:
connect(this,&ProcessWidget::destroyed,myProcess,&QProcess::kill);

Naveen_D

@VRonin if there are some huge debug statements and if i want a particular debug statement out of that means...now i am getting complete debug statements in my console...i want to choose a particular statement out of that. how to do this..?

VRonin

If what you are reading are strings then you can manipulate them the usual way, for example:

const QString processOut = QString::fromLatin1(myProcess->readAllStandardError());
const QRegularExpression regXp("MyField: (\\S+)");
const auto regXpMatch = regXp.match(processOut);
if(regXpMatch.hasMatch()){
qDebug() << "Output: "<< regXpMatch.captured(1);
}

Naveen_D

@VRonin sorry i didn't get the the regular exp part...
the actual scenario is, i will give the input at runtime via live microphone when the other process is started by this current Qprocess...and in that started process i am storing the input in a string and displaying through qDebug. those debug statements from the started process are now copied to my console, from which i need to take a particular string and pass it through a signal.

VRonin

@Naveen_D said in Regarding QProcess:: Not able to read data from the console:

which i need to take a particular string

I don't know how you identify the particular string so I just guessed a use based off a regular expression. what I mean is that instead of passing whatever you receive to your console with qDebug()<<"Output: "<< myProcess->readAllStandardOutput(); you can do whatever you want with the read data. For example, if you want to pass every line you receive to a signal you can use:

connect(myProcess,&QProcess::readyReadStandardError,[myProcess,this]()->void{
const QByteArray readData= myProcess->readAllStandardError();
QTextStream lineReader(readData);
QString tempLine;
while (lineReader.readLineInto(&tempLine)) {
/*emit*/ mySignal(tempLine);
}
        });

Naveen_D

@VRonin As said by you i am trying with Regular Exp,
the output at present i am getting is ...
Output: "loaded file >>>>>>> 0x1c57220 \n\n"
Output: "Recognition instance >>>>> 0x1c58660 \n\n"
Output: "\n<<< please speak >>> \n\n \n\n"
Output: "Sentence :\nchar *data>>>>>>> <s> \n\nchar *data>>>>>>> WORLD \n\nchar *data>>>>>>> </s> \n\nReceived Command: "WORLD" \n\n"

from this output i want to select the part which is in bold... but when i run my program and give output through a microphone i get the above output in my console...but i am not getting the regular exp qDebug part.

VRonin

What is your current code?

Also, if you have access to the source of the voice recognition software you can send data directly in raw format (using toBase64()) and receive it more easily

Naveen_D

@VRonin said in Regarding QProcess:: Not able to read data from the console:

Also, if you have access to the source of the voice recognition software you can send data directly in raw format (using toBase64()) and receive it more easily

First i tried using directly and was able to send the output through the signal...but voice recognition has some callback functions which does not return control back to the function from where it is called so...i made this voice recog as a separate process.

Naveen_D

@VRonin said in Regarding QProcess:: Not able to read data from the console:

What is your current code?

#include "ProcessWidget.h"

ProcessWidget::ProcessWidget(QWidget *parent)
    : QWidget(parent)
{
    m_btn= new QPushButton("click here",this);
    connect(m_btn,SIGNAL(clicked()),this,SLOT(vStartProcess()));
}

void ProcessWidget::vStartProcess()
{
    qDebug()<<"entered the function"<<endl;
    const QString program = QStringLiteral("/home/ubuntu/Documents/Sample_Examples_Qt_Qml/VoiceRecognition/VoiceRecognition");
    QProcess* myProcess = new QProcess;
//    connect(myProcess,&QProcess::readyReadStandardOutput,[myProcess]()->void{
//                qDebug()<<"Output: "<< myProcess->readAllStandardOutput()<<endl;
//            });
    connect(myProcess,&QProcess::readyReadStandardError,[myProcess]()->void{
                qDebug()<<"Output: "<< myProcess->readAllStandardError();
                const QString processOut = QString::fromLatin1(myProcess->readAllStandardError());
                const QRegularExpression regXp("Received Command");
                const auto regXpMatch = regXp.match(processOut);
                if(regXpMatch.hasMatch()){
                    qDebug() << "Output of regular exp is: "<< regXpMatch.captured(1);
                }
            });
    connect(myProcess,SIGNAL(finished(int)),myProcess,SLOT(deleteLater()));
    myProcess->start(program);
    qDebug()<<"process started waiting for output"<<endl;
    connect(this,&ProcessWidget::destroyed,myProcess,&QProcess::kill);

}

VRonin

I guess you are not really familiar with the perl regular expression syntax.
const QRegularExpression regXp("Received Command"); should be const QRegularExpression regXp("Received Command:\\s*(.+)");