How to produce Capital hexadecimal digits with QString::arg() ? [QT]

I'm trying to create a QString which is a hexadecimal nu开发者_如何学Cmber with its letter digits in Capitals instead of small caps, how can it be done?

QString( " %1" ).arg( 15, 1, 16 )

yields f and I'd like F

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By converting the string to upper case:

QString( " %1" ).arg( 15, 1, 16 ).toUpper();

This returns an uppercase string. The method used to be called upper() in qt3.