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problem using QFileSystemWatcher,unable to show log file output

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52GE

Beginner

  • "52GE" started this thread

Posts: 3

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1

Wednesday, April 11th 2012, 1:39pm

problem using QFileSystemWatcher,unable to show log file output

I am using QFileSystemWatcher to display the output of a log file to a QTextEdit.But i am still not getting the result,i think there is some mistake somewhere in my code,i can’t figure out.

Ui form appears for a fraction of second and then the application terminates unexpectedly.

here’s the code:-

LOGFILE.h

public slots:
void readContents(QString);



LOGFILE.cpp


logFile::logFile(QWidget *parent):QMainWindow(parent),ui(new Ui::logFile)
{
QFile *logFile = new QFile(" /var/log/system.log");
new QTextStream(logFile);
QFileSystemWatcher fileWatcher = new QFileSystemWatcher(this) ;
fileWatcher->addPath ("/var/log/system.log");
QObject::connect(fileWatcher, SIGNAL(fileChanged(QString)), this, SLOT(readContents(QString))) ;
}
void logFile::readContents(QString path)
{
QFile *logFile;
QString textAppended ;
int newSize = logFile->size();

int oldSize;
if(newSize > oldSize)
{
if(!logFile->open(QIODevice::ReadOnly))
{
textAppended = "Error in opening the File";
//showOutput();
ui->logTextEdit->setPlainText(textAppended);
return;
}
else
{
logFile->seek((logFile->size() - 1) - (newSize - oldSize));
QTextStream txtStream(logFile);
while(!txtStream.atEnd())
{
textAppended = txtStream.readLine();
}
// showOutput();
ui->logTextEdit->setPlainText(textAppended);
}
oldSize = newSize;
logFile->close();
}
}

Amleto

Professional

Posts: 1,430

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2

Wednesday, April 11th 2012, 4:10pm

your code is virtually impossible to read due to lack of code tags.

it also does not compile.

e.g.
QFileSystemWatcher fileWatcher = new QFileSystemWatcher(this) ;

please read my sig.

Source code

 
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void logFile::readContents(QString path) 
 { 
QFile *logFile; <<<----- pointer points to anywhere

if(!logFile->open(QIODevice::ReadOnly))   <<<------ pointer still points to random address.
If you have a problem, CUT and PASTE your code. Do not retype or simplify it. Give a COMPLETE and COMPILABLE example of your problem. Otherwise we are all guessing the problem from a fabrication where relevant details are often missing.

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