pass parent parameter to base class constructor

[phil_n]

Hi all,

I'm studying this book "C++ GUI programming with Qt4" trying to learn it but my C++ was always rudamentary and even that is very rusty. I'm trying to make sure I understand it rather than just copy out examples. So in one of the examples there is this construct:

FindDialog::FindDialog(QWidget *parent) : QDialog(parent)

FindDialog::FindDialog(QWidget *parent) : QDialog(parent)

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wich is described in the text this way:

we pass on the parent parameter to the base class constructor

then it's instantiated like this:

FindDialog *dialog = new FindDialog;

FindDialog *dialog = new FindDialog;

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ie. with no parameters.

Can anybody explain what is going on here? Or where I can read up on it (in newbie speak)?
I know it's sub-classing QDialog but what does 'parent' refer to? Where does it come from?

Thanks.