C++ - pointers in a QList

Question

I have a Class called File which contains a QTextEdit* (a textbox), a QWidget* (used to create tabs in a QTabWidget), a QString for holding an address of a file and a bool to check whether the file has been saved / modified.

I store these files in a QList (it's just like the std::list).

void MainWindow::newFile()
{
    QWidget* tab = new QWidget( tabWidget ); //QTabWidget is a member of MainWindow, it gets automatically deleted when MainWindow gets destryoed
    tabWidget->addTab( tab, tr("New Tab") ); //Add it to the QTabWidget
    tab->setLayout( new QHBoxLayout( tab ) );

    QTextEdit* textEdit = new QTextEdit( tab ); //When tab gets deleted, this also gets deleted
    tab->layout()->addWidget( textEdit );

    File *f = new File( this, textEdit, tab ); //Store both in a file
    fileList.push_back( f ); //Add it to the list (member of MainWindow)

    tabWidget->setCurrentIndex( tabWidget->count()-1 ); //Go to that tabPage
    f->textEdit()->setFocus(); //Set the focus to the textEdit
}

This creates a new tabpage, adds it to the QTabWidget, creates a layout for the tabpage, creates a new QTextEdit, adds it to the layout so it's filled and will automatically resize and finally it gets pushed back onto the QList so I can remove the tab etc.

Since the class File has pointers as member their objects on the heap have to be deleted. But when I try to delete them in the destructor I get a SIGSEGV and my program crashes.

File::~File()
{
delete m_textEdit; //QTextEdit* - Crashes here
delete m_tab; //QWidget* //Doesn't reach this line
}

My question now is, why does my program crash when I try to delete m_textEdit's object? This only happens when I close the window.

Also, do I have to delete the File* when I remove them from the list? Or does the list do it automatically for me? If so, how do I do it?

//delete fileList.at(0); //This would cause a crash
fileList.removeAt( 0 ); //removing for example the first index

Edit: Headerfile of File

class File : public QObject
{
    Q_OBJECT

    QTextEdit* m_textEdit;
    QWidget* m_tab;
    QString m_filepath;
    bool m_saved;

public:
    explicit File(QObject *parent = 0);
    File( const File& );
    File( QObject* parent, QTextEdit* textEdit = 0, QWidget* tab = 0, const QString& filepath = QString(), bool saved = true );
    ~File();

signals:
    void savedChanges( bool );

public slots:
 //Getters and setters only
};

Answer 1

The parent of the pointers to File is MainWindow so by destroying the parent those objects will be destroyed automatically, then you don't need to delete them and this is wrong:

delete fileList.at(0);

On the other hand, removing an item from fileList doesn't hurt and it's OK:

fileList.removeAt(0);

---

This is code doesn't make sense:

File::~File()
{
  delete m_textEdit; //QTextEdit* - Crashes here
  delete m_tab; //QWidget* //Doesn't reach this line
}

Because, you're getting m_textEdit and m_tab from the constructor, and you didn't new them by File. So, it's not correct to delete them here. Don't touch them.