[SOLVED] The program has unexpectedly finished.

[Renn]

Please check my code does something wrong? The problem is that when I open the file and close it, and I wanted to try to re-open the file appears this notification "The program has unexpectedly finished."

getFile = QFileDialog::getOpenFileName(
0,
tr("Open your file"),
"/home/rnd",
"All File (**);;Text(*.txt)"
);
if(!getFile.isEmpty())
{
QList <QMdiSubWindow *> subWindows = ui->mdiArea->subWindowList();
if (subWindows.count() > 0) {
for (int i = 0; i < subWindows.count(); i++) {
if (subWindows.at(i)->property("filePath").toString() == getFile) {
}
}
}
QString cache;
QFile file(getFile);
if (file.open(QFile::ReadOnly)) {
QTextStream in(&file);
while (!file.atEnd()) {
cache = in.readAll();
}
}
file.close();

    QFileInfo finfo(file);
    mdiWindow2 = ui->mdiArea->addSubWindow(widget);
    mdiWindow2->setGeometry(5, 5, 300, 250);
    mdiWindow2->setWindowTitle(finfo.baseName());
    mdiWindow2->layout()->addWidget(TextEdit);
    TextEdit->setPlainText(cache);
    mdiWindow2->show();

[Renn]

Full Code, there are changes a little

MultipleDocument.pro
QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = MultipleDocument
TEMPLATE = app

SOURCES += main.cpp
multipledocument.cpp

HEADERS += multipledocument.h

FORMS += multipledocument.ui

RESOURCES +=
Resource.qrc

QMAKE_CXXFLAGS += -std=c++0x

multipledocument.h

#ifndef MULTIPLEDOCUMENT_H
#define MULTIPLEDOCUMENT_H

#include <QMainWindow>
#include <QDebug>
#include <QMdiSubWindow>
#include <QWidget>
#include <QTextEdit>
#include <QFileDialog>

namespace Ui {
class MultipleDocument;
}

class MultipleDocument : public QMainWindow
{
Q_OBJECT

public:
explicit MultipleDocument(QWidget *parent = nullptr);
~MultipleDocument();

private slots:
void newFile();
void openFile();

private:
Ui::MultipleDocument ui;
QWidget widget;
QTextEdit* TextEdit;
QMdiSubWindow* mdiWindow;
QMdiSubWindow* mdiWindow2;

QString getFile;

};

#endif // MULTIPLEDOCUMENT_H

main.cpp

#include "multipledocument.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MultipleDocument w;
w.show();

return a.exec();

}

multipledocument.cpp

#include "multipledocument.h"
#include "ui_multipledocument.h"

MultipleDocument::MultipleDocument(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MultipleDocument)
{
ui->setupUi(this);
widget = new QWidget(this);
//TextEdit = new QTextEdit();
//TextEdit->setObjectName("textEdit");
connect(ui->actionNew_File, SIGNAL(triggered()), this, SLOT(newFile()));
connect(ui->actionOpen_File, SIGNAL(triggered()), this, SLOT(openFile()));
}

MultipleDocument::~MultipleDocument()
{
delete ui;
}

void MultipleDocument::newFile()
{
TextEdit = new QTextEdit(widget);
static int nomer = 1;
QString nameFile = tr("document %1.txt").arg(nomer++);
mdiWindow = ui->mdiArea->addSubWindow(widget);
mdiWindow->setWindowTitle("[*]" + nameFile);
mdiWindow->setGeometry(5, 5, 300, 250);
mdiWindow->layout()->addWidget(TextEdit);
mdiWindow->show();
}

void MultipleDocument::openFile()
{
getFile = QFileDialog::getOpenFileName(
0,
tr("Open your file"),
"/home/rnd/renaldi",
"All File (**);;Text(*.txt)"
);
if(!getFile.isEmpty())
{
QString cache;
QFile file(getFile);
if (file.open(QFile::ReadOnly | QFile::Text)) {
QTextStream in(&file);
while (!in.atEnd()) {
cache = in.readAll();
}
}

    QFileInfo fileInfo(file);
    mdiWindow2 = ui->mdiArea->addSubWindow(widget);
    mdiWindow2->setGeometry(5, 5, 300, 250);
    TextEdit = new QTextEdit(widget);
    mdiWindow2->setWindowTitle(fileInfo.baseName());
    mdiWindow2->layout()->addWidget(TextEdit);
    TextEdit->setPlainText(cache);
    mdiWindow2->show();
}

}

[Chris Kawa]

That's cause you're reusing the widget variable, which is destroyed after you close the first window. Also you're overwriting the TextEdit variable.

You don't need that extra widget there at all. It only does harm. Also you can have multiple sub-windows opened so you shouldn't put a pointer in a single TextEdit and mdiWindow variables. You don't need these either.
Change this in newFile():

TextEdit = new QTextEdit(widget);
mdiWindow = ui->mdiArea->addSubWindow(widget);
mdiWindow->layout()->addWidget(TextEdit);

to

ui->mdiArea->addSubWindow(new QTextEdit());

and accordingly in the openFile().

You can then access a list of all sub-windows with ui->mdiArea->subWindowList() and get the text edit from the widget() method.

Some other unrelated pointers:

• instead of QMAKE_CXXFLAGS += -std=c++0x in the .pro file use CONFIG += c++11, it's compiler agnostic
• make up your mind about your variable naming scheme. Using both lower case (mdiWindow) an upper case (TextEdit) is confusing. I suggest sticking to Qt's conventions in this area.
• When posting code surround it with ```, it makes it format better.

[Renn]

@Chris-Kawa Thank you in advance, this problem has been solved