如何释放内存？

Question

I have Created a simple QT application for my university assignment. What i have done is pop up a new QManinWindow from a Above QMainWindow. When i click a button from the main ui it will pop up a new QMainWindow object (Note Pad)

Note pad is also a QMainWindow object

My Problem is when I'm creating the object it takes some memory from the ram but when I'm closing it (pop up window) memory is not releasing. When each time I'm pressing a button memory is allocated but application does not relese the memory when im closing it. Please check the main screen of the app.

i just want to know how to release that memory. I have tried so many things but nothing worked well.

I have set the closeEvent public on NotePad class and I listen the close event from main object when its get triggered i have deleted the poped up object. But it cause ad unexpected stop.

void MainWindow::on_notePadBtn_clicked()
{

    NotePad *notePad = new NotePad(this);
    notePad->raise();
    notePad->activateWindow();
    notePad->show();
}


NotePad::NotePad(QWidget *parent) :QMainWindow(parent),ui(new Ui::NotePad) {

    ui->setupUi(this);
    this->setWindowTitle("Note Pad");
}

Answer 1

You don't really need to override closeEvent , Qt has Qt::WA_DeleteOnClose attribute, that does exactly what you want, you can use it like this:

//...
NotePad *notePad = new NotePad(this);
notePad->setAttribute(Qt::WA_DeleteOnClose);
notePad->raise();
notePad->activateWindow();
notePad->show();
//...

Answer 2

I'm not familiar with Qt.

But to my understanding if you use the operator new you must use delete (in a scope where you have access to the pointer created with new).

Object *foo = new Object();
// Do stuff with foo...
delete foo;
// DO NOT use foo from now on. 

Hope that helps a bit, maybe. Like I said I'm not familiar with Qt so if you have doubts about how some features are implemented you should look at the their docs.

(cf: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3797.pdf §3.7.4p63)