setNum() digits question

I am using a QLabel to display a number which ia a double.

Code:

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void QLabel::setNum ( double num )

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I don't want so many significant digits. How do I cut the number of significant digits?
I want 1.2345678 to display as 1.23

Code:

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QString s;
s = s.setNum(1.2345678, 'g', 2);
label->setText(s);

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