Localizing special parameters – currencies and dates with QLocale

A common thing you might need to do is localize currencies and dates. Qt makes this easy, although the solution isn't obvious until you've thought about it a bit. Let's try it out.

1. You need to know about the QString arg method. This replaces an escaped number with the formatted version of its argument. For example, if we write the following:

QString s = QString("%1 %2").arg("a").arg("b"); 

Then, s will contain the string "a b".

2. You need to know about the toString method of QLocale, which formats its argument in a locale-specific way. So, we could write the following:

QString currencyValue = QString("%1 %2") 
    .arg(tr("$")).arg(QLocale::toString(value, 'g', 2) 

This uses tr to localize the currency symbol and the QLocale...