creating objects in a for()

Hi,

I'm rather new to C++ and now I need a dynamic amount (int i) of buttons. I tried something (where I was sure that it wouldn't work, but just to tell you what I need) like this:

Code:

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int i; i=0;
	for(;i<9;i++){ 
		QLabel label(&fenster);
        label.setFrameStyle(QFrame::Panel | QFrame::Sunken);
        label.setText("first line\nsecond line");
        label.setAlignment(Qt::AlignTop | Qt::AlignLeft);
	label.setGeometry(10*i,80,120,50);
	}

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I know that normally it would be my job to learn C++ properly, but perhaps you could be so kind and correct the code given above.

Thanks.

Code:

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for(int i=0;i<9;i++){
  QLabel *label = new QLabel(&fenster);
  label->setFrameStyle(QFrame::Panel | QFrame::Sunken);
  label->setText("first line\nsecond line");
  label->setAlignment(Qt::AlignTop | Qt::AlignLeft);
  label->setGeometry(10*i,80,120,50);
}

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This will more or less work, but two more potential errors are here:

Code:

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QLabel *label = new QLabel(&fenster);

---

By that code I guess "fenster" is a stack allocated object which can go out of scope. It should be allocated on heap (just like I corrected the labels here)

Code:

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label->setGeometry(10*i,80,120,50);

---

Based on this I guess you are not using layouts, while you probably should.

Quote:

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Originally Posted by wysota

This will more or less work, but two more potential errors are here:

Code:

---

QLabel *label = new QLabel(&fenster);

---

By that code I guess "fenster" is a stack allocated object which can go out of scope. It should be allocated on heap (just like I corrected the labels here)

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Which means that your code should eventualy look like this *and* compile flawlesly:

Code:

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QLabel *label = new QLabel(fenster);

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Thank you very much, you were a great help!