I was trying to make a little program with Qt Framework C++ .
I made a simple Gui which contains 5 text inputs .
How can I save these inputs into a *.txt file with this schema :
Name : <firstInput>
Lastname : <secondInput>
Age : <ThirdInput>
Nationality : <forthInput>
Address : <fifthInput>
I still didn't do anything in my main.cpp
#include "monformulaire.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MonFormulaire w;
w.show();
return a.exec();
}
Here's an example:
QFile data("output.txt");
if (data.open(QFile::WriteOnly | QFile::Truncate)) {
QTextStream out(&data);
out << ui->lineEdit->text();
}
This tries to save contents of one of the LineEdits into a file named "output.txt". You would put this code into some on-button-clicked slot.
See:
QFile
QTextStream
QLineEdit
Related
My Qt windows application is ready, but when the application opens, I want the login dialog to be opened, how can I do this? I'm new to Qt and C++. It would be great if it was descriptive.
You have many ways to achieve that... QDialog is a nice way. Here is a short sample using QInputDialog.
One solution could be to add this code in your main.cpp file, and to load the mainwindow only if the credentials are ok.
#include "gmainwindow.h"
#include <QApplication>
#include <QInputDialog>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
GMainWindow w;
QString login = QInputDialog::getText(NULL, "Login","Name ?",QLineEdit::Normal);
if (login == "USER")
{
w.show();
}
else
{
//display an error message
return a.quit();
}
return a.exec();
}
Of course you may want to put an encrypted password and other things, but the idea will be more or less the same.
It's strange, I add desired file into the resources via Add Existing Files..., the file is there. I run qmake ("Build->Run qmake") to make the file available.
The first issue: I can't write anything into the file from output terminal! But when I manually write into the file, the output terminal shows the change every time I run it. Second issue: it still says QIODevice::read: device not open !
Here's my code:
#include <QCoreApplication>
#include <QDebug>
#include <QFile>
#include <QString>
#include <QTextStream>
#include <iostream>
void wFile(QString Filename)
{
QFile nFile(Filename);
QTextStream str(&nFile);
qDebug() << "what do you want to write in the desired file: ";
str.readLine();
if (!nFile.open(QFile::WriteOnly | QFile::Text))
{
qDebug() << "could not open the file";
return;
}
nFile.flush();
nFile.close();
}
void read (QString Filename){
QFile nFile(Filename);
if(!nFile.open(QFile::ReadOnly | QFile::Text))
{
qDebug() << "could not open file for reading";
return;
}
QTextStream in(&nFile);
QString nText = in.readAll();
qDebug() << nText;
nFile.close();
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QString nFilename =":/MyFiles/DocumentArminV.txt";
wFile(nFilename);
read(nFilename);
return a.exec();
}
And here's output terminal of the code:
The files saved in a qresource are read-only since they are part of the executable so you can not write or modify them.
docs:
Currently, Qt always stores the data directly in the executable, even on Windows, macOS, and iOS, where the operating system provides native support for resources. ...
It's strange, I add desired file into the resources via Add Existing Files..., the file is there. I run qmake ("Build->Run qmake") to make the file available.
The first issue: I can't write anything into the file from output terminal! But when I manually write into the file, the output terminal shows the change every time I run it. Second issue: it still says QIODevice::read: device not open !
Here's my code:
#include <QCoreApplication>
#include <QDebug>
#include <QFile>
#include <QString>
#include <QTextStream>
#include <iostream>
void wFile(QString Filename)
{
QFile nFile(Filename);
QTextStream str(&nFile);
qDebug() << "what do you want to write in the desired file: ";
str.readLine();
if (!nFile.open(QFile::WriteOnly | QFile::Text))
{
qDebug() << "could not open the file";
return;
}
nFile.flush();
nFile.close();
}
void read (QString Filename){
QFile nFile(Filename);
if(!nFile.open(QFile::ReadOnly | QFile::Text))
{
qDebug() << "could not open file for reading";
return;
}
QTextStream in(&nFile);
QString nText = in.readAll();
qDebug() << nText;
nFile.close();
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QString nFilename =":/MyFiles/DocumentArminV.txt";
wFile(nFilename);
read(nFilename);
return a.exec();
}
And here's output terminal of the code:
The files saved in a qresource are read-only since they are part of the executable so you can not write or modify them.
docs:
Currently, Qt always stores the data directly in the executable, even on Windows, macOS, and iOS, where the operating system provides native support for resources. ...
It's strange, I add desired file into the resources via Add Existing Files..., the file is there. I run qmake ("Build->Run qmake") to make the file available.
The first issue: I can't write anything into the file from output terminal! But when I manually write into the file, the output terminal shows the change every time I run it. Second issue: it still says QIODevice::read: device not open !
Here's my code:
#include <QCoreApplication>
#include <QDebug>
#include <QFile>
#include <QString>
#include <QTextStream>
#include <iostream>
void wFile(QString Filename)
{
QFile nFile(Filename);
QTextStream str(&nFile);
qDebug() << "what do you want to write in the desired file: ";
str.readLine();
if (!nFile.open(QFile::WriteOnly | QFile::Text))
{
qDebug() << "could not open the file";
return;
}
nFile.flush();
nFile.close();
}
void read (QString Filename){
QFile nFile(Filename);
if(!nFile.open(QFile::ReadOnly | QFile::Text))
{
qDebug() << "could not open file for reading";
return;
}
QTextStream in(&nFile);
QString nText = in.readAll();
qDebug() << nText;
nFile.close();
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QString nFilename =":/MyFiles/DocumentArminV.txt";
wFile(nFilename);
read(nFilename);
return a.exec();
}
And here's output terminal of the code:
The files saved in a qresource are read-only since they are part of the executable so you can not write or modify them.
docs:
Currently, Qt always stores the data directly in the executable, even on Windows, macOS, and iOS, where the operating system provides native support for resources. ...
I saved the QString in the file like this:
QString str="blabla";
QByteArray _forWrite=QByteArray::fromHex(str.toLatin1());
f.write(_forWrite); // f is the file that is opened for writing.
Then when I read the file I use QFile::readAll() to take the QByteArray but I don't know how to convert it to QString.
I tried to use the constructor that uses QByteArray but It didn't work out. I tried also with QByteArray::data() but same result. What I do wrong ?
It's not clear why you are calling QByteArray::fromHex at all. toLatin1() already return you QByteArray where each symbol encoded with one byte.
[UPDATE]
You should NOT call QByteArray::fromHex at all, because:
invalid characters in the input are skipped
And invalid characters are characters that are not the numbers 0-9 and the letters a-f
You can use QDataStream
#include <QApplication>
#include <QDataStream>
#include <QByteArray>
#include <QFile>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QString strToWrite = "blabla";
QFile fileToWrite("file.bin");
QDataStream dataStreamWriter(&fileToWrite);
fileToWrite.open(QIODevice::WriteOnly);
dataStreamWriter << strToWrite;
fileToWrite.close();
QString strToRead = "";
QFile fileToRead("file.bin");
QDataStream dataStreamReader(&fileToRead);
fileToRead.open(QIODevice::ReadOnly);
dataStreamReader >> strToRead;
fileToRead.close();
qDebug() << strToRead;
return app.exec();
}
Output : "blabla"