QUrl, right coding for paths - qt

I have a problem with coding. I'm using drag and drom inside my application but some text files I can not open, after some searching I find that the path is with wrong coding. The real file is 'Some_file - 01.txt' but when I try print this path (after drop) to the stdout I will get 'Some_file – 01.txt'. What I miss:
void MainWindow::dropEvent(QDropEvent *event) {
QList<QUrl> urls = event->mimeData()->urls();
...
cout << paths[1].toLocalFile() << endl; /* Some_file – 01.txt */
cout << paths[1].toEncoded() << endl; /* Some_file%20%E2%80%93%2001.txt */
}
I also try QString::fromLatin1 or fromUtf8 but without success.
I'm using QT 4.7.0 and Windows 7.
Edit:
This is my main setup:
QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));
QTextCodec::setCodecForTr(QTextCodec::codecForName("UTF-8"));
QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
And unfortunately even this is not working for me:
QString fileName = QFileDialog::getOpenFileName(this, tr("Load EEPROM from HEX file"), "", tr("HEX file (*.hex)"));
ifstream hexFile(fileName.toStdString().c_str());
I'm not able to open files where the char '-' is part of file name.
EDIT2:
If I change the file name manualy from 'file.txt' to 'file-.txt' everything is working well. But when I (the same file) copy and paste this file to the same folder, windows will generate new name with postfix: 'file - copy.txt' and this file I can NOT open. So the Windows is using different character for '-' vz. '–'.
What I can do ?
Solution:
void openFile(string fileName) {
ifstream fileio(fileName.c_str());
}
QString qtFileName = QFileDialog::getOpenFileName(...)
openFile(qtFileName.toLocal8Bit().constData());

std::cout is encoded with some local encoding. What you need is to convert the QString returned by the toLocalFile() into a local 8 bit encoding.
For example:
QUrl url = ...;
QString filePath = url.toLocalFile();
QByteArray filePath8 = filePath.toLocal8Bit();
std::cout << filePath8.constData();
But really, the whole exercise is not necessary, since to access the files you should be using QFile, which takes a QString directly, and console output can be done using QTextStream. To wit:
#include <cstdio>
#include <QTextStream>
#include <QFile>
QTextStream out(stdout);
void test() {
out << filePath;
QFile file(filePath);
if (file.open(QIODevice::ReadOnly)) {
...
}
}

Related

Qt Enconding Error when returning spanish characters from server php script

So I've been doing some tests regarding enconding errors that I've seen around ñ charcater using CURL, Qt and sever side PHP. I've finally got a super minimalistic example where the error is in the Qt side ONLY. Maybe some one can help me out.
The Qt Code is as follows:
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QString address = "http://localhost/api_test/test.php";
QUrl url(address);
QNetworkAccessManager manager;
QNetworkRequest request(url);
QNetworkReply *reply = manager.post(request, QByteArray());
QObject::connect(reply, &QNetworkReply::finished, QCoreApplication::quit);
a.exec();
if(reply->error() == QNetworkReply::NoError){
qDebug() << "The output";
qDebug() << QString(reply->readAll()).toUtf8();
}
else{
qDebug() << reply->error() << reply->errorString();
}
delete reply;
return 0;
}
On the server side, test.php is as follows:
<?php
$data = file_get_contents("uploaded.json");
echo "$data\n";
?>
Where "uploaded.json" is a plain text file that contains
{"name" : "Ariel ñoño", "age" : 58}
The curl command now works as expected
ariel#ColoLaptop:/home/web/api_test$ curl http://localhost/api_test/test.php
{"name" : "Ariel ñoño", "age" : 58}
But when I run the Qt Application, this happens:
The output
"{\"name\" : \"Ariel \xC3\xB1o\xC3\xB1o\", \"age\" : 58} \n\n"
Again the ñ characters get screwed. Can anyone tell me what is wrong with the Qt Code or how can I interpret the returned byte string correctly?
The "ñ" is unicode text so using toUtf8() won't do the trick. You have to use a QTextDecoder
qDebug() << "The output";
QTextCodec* codec = QTextCodec::codecForLocale();
QTextDecoder* decoder = codec->makeDecoder();
QString text = decoder->toUnicode(reply->readAll());
qDebug() << text;
Output:
The output
"{\"name\" : \"Ariel ñoño\", \"age\" : 58}\n"

QTextStream readAll() removes Newlines

I am using QFile and QTextStream to first read a file and then write the read contents unmodified back into the same file. Here is the code:
QFile inFile("file.txt");
if(!inFile.open(QFile::ReadOnly | QFile::Text))
{
qCritical() << "ERROR: Unable to open input file: " << "file.txt";
exit(1);
}
QTextStream inStream(&inFile);
QString fileContents = inStream.readAll();
inFile.close();
QFile outFile("file.txt");
if(!outFile.open(QFile::WriteOnly | QFile::Text))
{
qCritical() << "ERROR: Unable to open output file: " << "file.txt";
exit(1);
}
QTextStream outSream(&outFile);
outSream << fileContents;
outFile.close();
However, this transforms the file.txt given below:
1
2
3
4
5
into
12345
i.e. newlines are getting removed in this process. Why is this happening? How can I prevent it?
The QIODevice::Text flag passed to open() tells Qt to convert Windows-style line terminators (\r\n) into C++-style terminators (\n).
Are you operating in Windows? You should be able to see the \r\n in a binary editor on the input and the output file.
About QIODevice::Text in openMode the official document says.
When reading, the end-of-line terminators are translated to '\n'. When writing, the end-of-line terminators are translated to the local encoding, for example '\r\n' for Win32.
It says Win32,while working on Win64,Qt5.8 I found it works differently.
With QIODevice::Text in openMode, QIODevice::readAll() remove all '\r','\t'.
And talk about \n,they are replaced by \r whatever openMode is using.
May be removed if using QIODevice::Text mode.
The solution is to not use QFile::Text or QIODevice::Text, if you are reading, just use QIODevice::ReadOnly , in that way you can also figure out the exact line ending used and handle them appropriately. I had this problem with Mac(CR) or '\r' line ending while opening with QIODevice::Text.

Files getting corrupted when being downloaded using QNetworkAcessManager

I'm developing a client app whose purpose is to download some files from a web server, temporarily store them in the Temp folder, check for file integrity, then send them to a FTP server in a Embedded Linux device.
Recently I got problems when doing the process in a preliminary development stage when I was trying to do the download from my local machine (see related question here). Now I'm able to download and upload without errors and with verification (I'm using QCryptographicHash + file size to check for any nonconformities) from my machine, but the same doesn't happen when I try downloading from the HTTP server.
There is a total of 8 files being downloaded: three .tar.gz, one simple text, two programs and two binaries. I'm able to successfully download all compressed files, the text file and one of the binaries, but the others, namely the two programs and one of the binaries (a Linux Kernel image) are always being incorrectly downloaded.
I check this by noticing not only that the hash returns error for them, but also for their sizes: their sizes are always wrong (and always the same erroneous value for any download attempt). And the files in the server are all correct.
My first suspicion was that I need to configure the HTTP download in a way that differs from the common FTP download from the local machine, but I'm unaware on how would that be. Moreover if this extra configuration was needed, then why some of the files always return correctly?
Here is the relevant code as for now:
void MainWindow::processNextDownload()
{
QUrl ulrTemp(updateData.at(transferStep).downloadUrl.arg(ui->leID->text())); //"//" +
if (updateData.at(transferStep).downloadUrl.contains("http"))
ulrTemp.setScheme("http");
else
ulrTemp.setScheme("file");
// ulrTemp.setUserName();
// ulrTemp.setPassword();
// ulrTemp.setPort();
qDebug() << "Downloading" << transferStep << "from" << ulrTemp;
#if 1
poReply = downloadNetworkManager->get(QNetworkRequest(ulrTemp));
#else
QNetworkRequest request;
request.setUrl(ulrTemp);
request.setRawHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.17 (KHTML, like Gecko) Chrome/24.0.1312.60 Safari/537.17");
poReply = downloadNetworkManager->get(request);
#endif
connect(poReply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(slotDownloadProgress(qint64,qint64)));
ui->statusBar->showMessage(tr("Downloading: %1").arg(updateData.at(transferStep).itemName));
}
void MainWindow::slotFileDownloaded(QNetworkReply* reply)
{
if (reply && (reply->error() != QNetworkReply::NoError))
{
ui->statusBar->clearMessage();
if (!isSingleFile)
{
const QString strTemp = tr("An error occurred while downloading \"%1\": %2 (error message: %3)")
.arg(updateData.at(transferStep).downloadName).arg(reply->error()).arg(reply->errorString());
QMessageBox::critical(this,tr("Error in download"),strTemp);
}
else
{
//irrelevant...
}
finished(false);
return;
}
qDebug() << "To write: " << reply->bytesAvailable();
QByteArray downloadedData = reply->readAll();
reply->deleteLater();
poReply->deleteLater();
//![]
static const QString tempFilePath = QDir::tempPath();
if (!isSingleFile)
{
QFile file(tempFilePath + "/" + updateData.at(transferStep).downloadName);
if (!file.open(QFile::WriteOnly | QFile::Truncate))
{
qDebug() << "Failure opening temp file to write: " << file.fileName();
QMessageBox::critical(this,
tr("Error"),
tr("An error occured while trying to open a temporary file to write the downloaded data (file: %1).").arg(file.fileName()));
transferStep = downloadStepCount;
slotFileUploaded(NULL);
return;
}
qint32 bytesWritten = file.write(downloadedData);
file.flush();
if (downloadedData.size() != bytesWritten)
qDebug() << "Write failed, wrote" << bytesWritten << "out of" << downloadedData.size() << "bytes.";
else
qDebug() << "Wrote " << bytesWritten << "bytes.";
file.close();
//![]
if (++transferStep >= downloadStepCount)
{
qDebug() << "Start hash check";
slotStartHashCheck();
return;
}
processNextDownload();
}
else
{
//irrelevant...
}
}
And this is why I get (the last number value after the "=" in the hash code is the file size):
So what am I missing?

qDebug not showing __FILE__,__LINE__

According to qlogging.h
#define qDebug QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO).debug
but when I use like this, file,line,function name not show.
qDebug()<< "abc"; // only show abc;
qDebug()<< ""; // show nothing;
I search for a while, it seems no one had my problem like above.
I use ubuntu14.04,g++ version 4.8.2, qt5.3 build from git.
You can reformat from default output format.
This function was introduced in Qt 5.0.
The line number does not output because the default message pattern is "%{if-category}%{category}: %{endif}%{message}". This format means that the default outputting format is not including metadata like a line number or file name.
% cat logtest.pro
TEMPLATE = app
TARGET = logtest
mac:CONFIG-=app_bundle
SOURCES += main.cpp
% cat main.cpp
#include <QCoreApplication>
#include <QDebug>
int main(int argc, char *argv[])
{
qSetMessagePattern("%{file}(%{line}): %{message}");
QCoreApplication a(argc, argv);
qDebug() << "my output";
return 0;
}
% qmake && make
% ./logtest
main.cpp(8): my output
You can also use QT_MESSAGE_PATTERN environment variable for setting the message pattern without calling qSetMessagePattern().
See reference for other placeholder. http://qt-project.org/doc/qt-5/qtglobal.html#qSetMessagePattern
If you dig in Qt history you can find out that the __FILE__ and __FUNCTION__ are logged only in debug builds since 1 Oct 2014. The git commit hash is d78fb442d750b33afe2e41f31588ec94cf4023ad. The commit message states:
Logging: Disable tracking of debug source info for release builds
Tracking the file, line, function means the information has to be
stored in the binaries, enlarging the size. It also might be a
surprise to some commercial customers that their internal file &
function names are 'leaked'. Therefore we enable it for debug builds
only.
Here's a simple example of how you might use the captured QMessageLogContext data in a custom message handler installed using qInstallMessageHandler. I didn't output the category or version members because they didn't seem useful. If desired you could also log to a file this way.
#include <QDebug>
#include <QString>
#include <QDateTime>
#include <iostream>
void verboseMessageHandler(QtMsgType type, const QMessageLogContext &context, const QString &msg)
{
static const char* typeStr[] = {"[ Debug]", "[ Warning]", "[Critical]", "[ Fatal]" };
if(type <= QtFatalMsg)
{
QByteArray localMsg = msg.toLocal8Bit();
QString contextString(QStringLiteral("(%1, %2, %3)")
.arg(context.file)
.arg(context.function)
.arg(context.line));
QString timeStr(QDateTime::currentDateTime().toString("dd-MM-yy HH:mm:ss:zzz"));
std::cerr << timeStr.toLocal8Bit().constData() << " - "
<< typeStr[type] << " "
<< contextString.toLocal8Bit().constData() << " "
<< localMsg.constData() << std::endl;
if(type == QtFatalMsg)
{
abort();
}
}
}
int main()
{
//Use default handler
qDebug() << "default handler";
qWarning() << "default handler";
qCritical() << "default handler";
//Install verbose handler
qInstallMessageHandler(verboseMessageHandler);
qDebug() << "verbose handler";
qWarning() << "verbose handler";
qCritical() << "verbose handler";
//Restore default handler
qInstallMessageHandler(0);
qDebug() << "default handler";
qWarning() << "default handler";
qCritical() << "default handler";
return 0;
}
You can use standard C++'s __LINE__ and __FILE__. Also, take a look at What's the difference between __PRETTY_FUNCTION__, __FUNCTION__, __func__ SO question. If you use GCC, you can write __PRETTY_FUNCTION__ to get information about function from where the code executes. Just prepare debug-define you like.
For example, here is small compilable application:
#include <QApplication>
#include <QDebug>
#include <iostream>
// Qt-way
#define MyDBG (qDebug()<<__FILE__<<__LINE__<<__PRETTY_FUNCTION__)
// GCC
#define MyStdDBG (std::cout<< __FILE__<<":"<<__LINE__<<" in "<<__PRETTY_FUNCTION__<<std::endl)
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
// Qt-way
MyDBG;
MyDBG << "Something happened!";
// GCC
MyStdDBG;
return a.exec();
}
It gives next output:
../path/main.cpp 14 int main(int, char**)
../path/main.cpp 15 int main(int, char**) Something happened!
../path/main.cpp:18 in int main(int, char**)
UPD: Added pure C++-way to output.
I think you need to define:
#define qDebug() QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO).debug()
and use it as
qDebug() << "abc";
or
#define qDebug QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO).debug()
and use it as:
qDebug << "abc";
According to documentation qDebug() is already a macro to QMessageLogger(). Default Message handler prints only the message to stderr. I think you might want to use qInstallMessageHandler() to install your own message handler, that uses the context
Edit:
There is a relevant section in a manual, that describes this issue. In Qt4 context variable was not passed to installed message handler, so this solution is Qt5+ only. Default message handler does not make use of passed in context, but you can easily install your own, it's just a function pointer. There is even an example in the manual.
This depends on your Qt version number, whether you are using a debug build or a release build of Qt, and whether you have customized Qt message handling in your application.
According to Qt 5.4 documentation written in source code "qlogging.cpp":
QMessageLogger is used to generate messages for the Qt logging framework. Usually one uses
it through qDebug(), qWarning(), qCritical, or qFatal() functions,
which are actually macros: For example qDebug() expands to
QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO).debug()
for debug builds, and QMessageLogger(0, 0, 0).debug() for release builds.
So if you do not see file, line and function name information in your output, very likely you are using a release version of Qt.
If you still want to see the file, line and function name information in your output with a release version of Qt, there are several ways of achieving it, as very well explained in some of the previous answers.
If you wonder how to get the debug context in a non-debug build: Define QT_MESSAGELOGCONTEXT while compiling your code, and the information won't be stripped:
http://doc.qt.io/qt-5/qmessagelogcontext.html

QProcess problems, output of process

I am trying to figure out the use of QProcess. I looked at Qt doc with no luck.
http://doc.qt.io/qt-4.8/qprocess.html
EXAMPLES OF PROBLEM.
Example 1: Code bellow works.
#include <QtCore/QCoreApplication>
#include <QTextStream>
#include <QByteArray>
#include <QProcess>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QTextStream qout(stdout);
QProcess cmd;
cmd.start("cmd");
if (!cmd.waitForStarted()) {
return false;
}
cmd.waitForReadyRead();
QByteArray result = cmd.readAll();
//qout << result.data() << endl; //console junk captured, doesn't show.
//My test command
cmd.write("echo hello");
cmd.write("\n");
//Capture my result
cmd.waitForReadyRead();
//This is my command shown by cmd, I don't show it, capture & discard it.
result = cmd.readLine();
//Read result of my command ("hello") and the rest of output like cur dir.
result = cmd.readAll();
qout << result.data();
qout << "\n\n---End, bye----" << endl;
return a.exec();
}
The output of the above code is
hello
F:\Dev_Qt\expControllingExtConsoleApps-build-desktop>
---End, bye----
The problem is that if I try to use ipconfig or 7zip in this fashion via Qprocess and cmd console, I am unable to see any output from ipconfig or 7zip. I don't know if anything is even done, if something is done then why can't I see the output? Code below illustrates.
Example 2: Does not work. Can't use ipconfig.
#include <QtCore/QCoreApplication>
#include <QTextStream>
#include <QByteArray>
#include <QString>
#include <QProcess>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QTextStream qout(stdout);
QProcess cmd2;
cmd2.setWorkingDirectory("C:/Program Files/7-Zip"); //not needed in this example.
cmd2.setReadChannel(QProcess::StandardOutput);
cmd2.setProcessChannelMode(QProcess::MergedChannels);
cmd2.start("cmd");
if (!cmd2.waitForStarted())
{
qout << "Error: Could not start!" << endl;
return false;
}
cmd2.waitForReadyRead();
QByteArray result = cmd2.readAll();
qout << result.data() << endl; //Console version info, etc.
//My command
cmd2.write("ipconfig");
cmd2.write("\n");
//Capture output of ipconfig command
//DOES NOT WORK!!
cmd2.waitForReadyRead();
while (! cmd2.atEnd())
{
result = cmd2.readLine();
qout << result;
result.clear();
}
qout << endl;
qout << "\n\n---end----" << endl;
return a.exec();
}
Output is below, it is missing the ipconfig connection information result. No output from ipconfig is captured at all.
Microsoft Windows XP [Version
5.1.2600] (C) Copyright 1985-2001 Microsoft Corp.
C:\Program Files\7-Zip> ipconfig
---end----
Should have been more like this (with ipconfig result).
Microsoft Windows XP [Version
5.1.2600] (C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and
Settings\noname>ipconfig
Windows IP Configuration
Ethernet adapter Local Area
Connection:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 192.172.148.135
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.172.148.177
C:\Documents and Settings\noname>
Obviously the output should should have been a little diff than above but the Connection info which is the output of "ipconfig" should have been captured. In the same way if I try to use 7zip via cmd console... I can not see/capture any output of 7zip. So my question is how can I use command line apps like ipconfig and 7zip via QProcess and cmd console and see the result of the output of these applications?
Example 3: 7zip does not work
#include <QtCore/QCoreApplication>
#include <QTextStream>
#include <QByteArray>
#include <QProcess>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QTextStream qout(stdout);
QProcess cmd2;
cmd2.setWorkingDirectory("C:/Program Files/7-Zip");
cmd2.setReadChannel(QProcess::StandardOutput);
cmd2.setProcessChannelMode(QProcess::MergedChannels);
cmd2.start("cmd");
if (!cmd2.waitForStarted()) {
return false;
}
//My Command
cmd2.write("7z.exe");
cmd2.write("\n");
//Capture output of ipconfig command
cmd2.waitForReadyRead();
QByteArray result;
while (! cmd2.atEnd()) {
result = cmd2.readLine();
qout << result;
result.clear();
}
qout << endl;
qout << "\n\n---end----" << endl;
return a.exec();
}
Output below. Does not show anything from 7zip.
Microsoft Windows XP [Version
5.1.2600] (C) Copyright 1985-2001 Microsoft Corp.
C:\Program Files\7-Zip>7z.exe
---end----
Output is expected to be along the lines of...
Microsoft Windows XP [Version
5.1.2600] (C) Copyright 1985-2001 Microsoft Corp.
C:\Documents and Settings\noname>cd
C:\Program Files\7-Zip
C:\Program Files\7-Zip>7z.exe
7-Zip 9.15 beta Copyright (c)
1999-2010 Igor Pavlov 2010-06-20
Usage: 7z [...]
<archive_name> [<file_names>...]
[<#listfiles...>]
a: Add files to archive
b: Benchmark d: Delete files from
archive e: Extract files from
archive (without using directory
names) l: List contents of archive
t: Test integrity of archive u:
Update files to archive x: eXtract
files with full paths
-ai[r[-|0]]{#listfile|!wildcard}: Include archives
-ax[r[-|0]]{#listfile|!wildcard}: eXclude archives -bd: Disable
percentage indicator
-i[r[-|0]]{#listfile|!wildcard}: Include filenames -m{Parameters}:
set compression Method
-o{Directory}: set Output directory -p{Password}: set Password -r[-|0]: Recurse subdirectories -scs{UTF-8 |
WIN | DOS}: set charset for list files
-sfx[{name}]: Create SFX archive -si[{name}]: read data from stdin -slt: show technical information for l (List) command -so: write data to
stdout -ssc[-]: set sensitive case
mode -ssw: compress shared files
-t{Type}: Set type of archive -u[-][p#][q#][r#][x#][y#][z#][!newArchiveName]:
Update options -v{Size}[b|k|m|g]:
Create volumes -w[{path}]: assign
Work directory. Empty path means a
temporary directory
-x[r[-|0]]]{#listfile|!wildcard}: eXclude filenames -y: assume Yes on
all queries
C:\Program Files\7-Zip>
eI see one big problem.
Under windows you issue a commend pressing the Enter key. Writing
cmd.write("command");
cmd.write("\n");
just isn't enough you have to write
cmd.write("command");
cmd.write("\n\r");
Notice the trailing \r. Try this, it should work better, and by better I mean 7zip. I don't know if you'll get ipconfig to work properly.
Good luck and best regards
D
EDIT
Here is a working solution:
#include <QtCore/QCoreApplication>
#include <QtCore/QProcess>
#include <QtCore/QString>
#include <QtCore/QTextStream>
// Not clean, but fast
QProcess *g_process = NULL;
// Needed as a signal catcher
class ProcOut : public QObject
{
Q_OBJECT
public:
ProcOut (QObject *parent = NULL);
virtual ~ProcOut() {};
public slots:
void readyRead();
void finished();
};
ProcOut::ProcOut (QObject *parent /* = NULL */):
QObject(parent)
{}
void
ProcOut::readyRead()
{
if (!g_process)
return;
QTextStream out(stdout);
out << g_process->readAllStandardOutput() << endl;
}
void
ProcOut::finished()
{
QCoreApplication::exit (0);
}
int main (int argc, char **argv)
{
QCoreApplication *app = new QCoreApplication (argc, argv);
ProcOut *procOut = new ProcOut();
g_process = new QProcess();
QObject::connect (g_process, SIGNAL(readyReadStandardOutput()),
procOut, SLOT(readyRead()));
QObject::connect (g_process, SIGNAL(finished (int, QProcess::ExitStatus)),
procOut, SLOT(finished()));
g_process->start (QLatin1String ("cmd"));
g_process->waitForStarted();
g_process->write ("ipconfig\n\r");
// Or cmd won't quit
g_process->write ("exit\n\r");
int result = app->exec();
// Allright, process finished.
delete procOut;
procOut = NULL;
delete g_process;
g_process = NULL;
delete app;
app = NULL;
// Lets us see the results
system ("pause");
return result;
}
#include "main.moc"
Hope that helps. It worked everytime on my machine.
Even though Dariusz Scharsig already provided a solution to the problem, I would like to point out what I believe to be the actual problem(s) which can be solved using the signal slot mechanism.
Problem 1. The condition in your while loop is based on bool QProcess::atEnd () const which is according to QProcess Documentation states:
Reimplemented from QIODevice::atEnd().
Returns true if the process is
not running, and no more data is available for reading; otherwise
returns false.
But if you looking the documentation for QIODevice::atEnd(), it states:
Returns true if the current read and write position is at the end of
the device (i.e. there is no more data available for reading on the
device); otherwise returns false.
For some devices, atEnd() can return
true even though there is more data to read. This special case only
applies to devices that generate data in direct response to you
calling read() (e.g., /dev or /proc files on Unix and Mac OS X, or
console input / stdin on all platforms).
Solution 1. Change the while loop condition to check the state of your process: while(cmd2.state()!=QProcess::NotRunning){.
Problem 2. You use cmd2.waitForReadyRead(); outside of the loop. Perhaps some data is ready for reading now and when you finished reading, some more gets made available:
you read the commands you just wrote : ipconfig\n
ipconfig takes some time to start up and send text to the console. But by then you have already exited your loop because atEnd() gave true even though your process is still running.
Solution 2. place the waitForReadyRead() inside your loop.
Consequence 2. waitForReadyRead() will tell you when there is data available, which could be more than one Line, so you should consequently also change the cmd2.ReadLine() to cmd2.ReadAll().
Problem 3. As documented in QProcess::closeWriteChannel()
Closing the write channel is necessary for programs that read input
data until the channel has been closed.
Solution 3. One of the following options should work when finished writing your inputs
End the process: cmd2.write("exit\n");
close the Writechannel: cmd2.closeWriteChannel();
Working code:
#include <QtCore/QCoreApplication>
#include <QTextStream>
#include <QByteArray>
#include <QString>
#include <QProcess>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QTextStream qout(stdout);
QByteArray result;
QProcess cmd2;
cmd2.setReadChannel(QProcess::StandardOutput);
cmd2.setProcessChannelMode(QProcess::MergedChannels);
cmd2.start("cmd");
if (!cmd2.waitForStarted()){
qout << "Error: Could not start!" << endl;
return 0;
}
cmd2.write("ipconfig\n");
cmd2.closeWriteChannel(); //done Writing
while(cmd2.state()!=QProcess::NotRunning){
cmd2.waitForReadyRead();
result = cmd2.readAll();
qout << result;
}
qout << endl << "---end----" << endl;
return a.exec();
}
I wrote this answer just to explain the way I understand your problem and found a solution but would like to emphasize that the Preferable Solution is to use the Signal/Slot Mechanism as presented by Dariusz.

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