[Qt-interest] Fwd: About QProcess :How to read stdoutput realtime?

[chandrasekar wagmare]

---------- Forwarded message ----------
From: chandrasekar wagmare <sekarwagmare at gmail.com>
Date: Tue, May 5, 2009 at 3:33 PM
Subject: Re: [Qt-interest] About QProcess :How to read stdoutput realtime?
To: "Princy K. V." <princy.kv at nestgroup.net>


it's a problem of an incorrectly setup buffering method... and
you won't be able to solve this from within your calling program.
Either "patch" the program you are calling to use line buffering --
setlinebuf(stdout) -- or use fflush(stdout) every now and then in this
program. If you can't do this, then there's no way to solve it.

It's NOT a problem of QProcess or anything you could solve by any trickery
here... I have similar issues with some of the programs that I call from
some
of my apps and there's no way around it (at least no platform independent
one).
ex: i am using linux to run an external system call glxgears in QProcess and
i get output after ten minutes only or when the buffer filled completly ..
        i try this one "glxgears | less" and find the problem in buffer
flush

On Tue, May 5, 2009 at 2:43 PM, Princy K. V. <princy.kv at nestgroup.net>wrote:

>  Hi,
>
> Thanks for ur reply.
>
> But slot is not invoked when I used these signals  *readyReadStandardError
> * <http://qprocess.html#readyReadStandardError> () & *
> readyReadStandardOutput* <http://qprocess.html#readyReadStandardOutput> (
>
> ..so I used following code snippets, this consumes lot of time..sometimes
> not getting desired output..
>
>
>
> void CMainWindow::Run()
>
> {
>
> QByteArray byteArray;
>
> byteArray.resize(2000);
>
> byteArray.clear();
>
> ui->plainTextEdit->setEnabled(true);
>
> ui->plainTextEdit->clear();
>
> while(!Start())
>
> {
>
> //progress->hide();
>
> byteArray.clear();
>
> byteArray=process->readAllStandardOutput();
>
> ui->plainTextEdit->appendPlainText(byteArray);
>
> }
>
> }
>
>
>
> void CMainWindow::Start()
>
> {
>
> …….
>
> process->start("xx.exe" ,arguments);
>
> if (!process->waitForStarted())
>
> return false;
>
> // ui->statusBar->addPermanentWidget(progress , 0);
>
> if(!process->waitForFinished())
>
> {
>
> //progress->setMinimum(0);
>
> //progress->setMaximum(0);
>
> //progress->show();
>
> return false;
>
> }
>
> ……
>
> return true;
>
> }
>
>
>
>
>
>
>  ------------------------------
>
>
>
> u are using this signals right ,
>
>  void *readyReadStandardError*<http://qprocess.html#readyReadStandardError>()
>
> void *readyReadStandardOutput*<http://qprocess.html#readyReadStandardOutput>()
>
>
>
> On Tue, May 5, 2009 at 1:04 PM, Princy K. V. <princy.kv at nestgroup.net>
> wrote:
>
> Hi,
>  I m new to Qt.I want to display datas that are written on stdoutput by
> an external process on my gui. I have started external process using
> Qprocess. I can display all stdoutput data by calling,
> byteArray=process->readAllStandardOutput();
> ui->plainTextEdit->appendPlainText(byteArray);
> But my reqiurment is to display data(line by line) same time it is
> written on stdoutput.i have tried many methods.so far didn't get
> required output..
> Please suggest me some solutions..
> Thanks..
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> --
> WAGMARE
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> This message and any attachments is intended for the sole use of the
> intended recipient. It may contain confidential information. Any
> unauthorized use, dissemination or modification is strictly prohibited. If
> you are not the intended recipient, please notify the sender immediately
> then delete it from all your systems, and do not copy, use or print.
> Internet communications are not secure and it is the responsibility of the
> recipient to make sure that it is virus/malicious code exempt.
>
> The company/sender cannot be responsible for any unauthorized alterations
> or modifications made to the contents. If you require any form of
> confirmation of the contents, please contact the company/sender. The
> company/sender is not liable for any errors or omissions in the content of
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>



-- 
WAGMARE



-- 
WAGMARE
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