In "Localization Demonstration": http://www.boost.org/doc/libs/1_47_0/doc/html/date_time/examples.html#date_t... 11 should be 12 and 6 should be 7 in the following lines: std::copy(&de_short_month_names[0], &de_short_month_names[11], std::back_inserter(short_months)); std::copy(&de_long_month_names[0], &de_long_month_names[11], std::back_inserter(long_months)); std::copy(&de_short_weekday_names[0], &de_short_weekday_names[6], std::back_inserter(short_weekdays)); std::copy(&de_long_weekday_names[0], &de_long_weekday_names[6], std::back_inserter(long_weekdays)); Regards, Frédéric