Qt3 to Qt4 printer setup confusion

[impeteperry]

In QT3 the code

QPrinter myprinter;	// = new QPrinter();
	myprinter.setPageSize( QPrinter::Letter );
	myprinter.setOrientation( QPrinter::Portrait );
	myprinter.setColorMode( QPrinter::Color );
	myprinter.setFullPage ( true );
	ret = myprinter.setup();
	if( ret == true )
	{
		QPainter p( &myprinter );

QPrinter myprinter;	// = new QPrinter();
	myprinter.setPageSize( QPrinter::Letter );
	myprinter.setOrientation( QPrinter::Portrait );
	myprinter.setColorMode( QPrinter::Color );
	myprinter.setFullPage ( true );
	ret = myprinter.setup();
	if( ret == true )
	{
		QPainter p( &myprinter );

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gave the user of a program the oppurtunity to change the default perameters for a print out. Qt4 says to use "QPrintDialog printDialog" for this.
The "Detailed Description" for this function says

Typically, QPrintDialog objects are constructed with a QPrinter object, and executed using the exec() function.

QPrintDialog printDialog(printer, parent);
if (printDialog.exec() == QDialog::Accepted) {
// print ...
}

I am a bit of a newbie in deciphering Qt4's style of documentation and with no print examples that I can find I need help.

Thanks