Working with date and time, time spans, time zones as well ... - Poco

DateTimeFormatter Functions
> All functions of DateTimeFormatter are static.
> std::string format(const Timestamp& timestamp,
const std::string& fmt, int tzd = UTC)
formats the given Timestamp according to the given format
string fmt. The time zone differential (tzd) is optional.
> std::string format(const DateTime& dateTime,
const std::string& fmt, int tzd = UTC)
is similar to the previous function, except that this one accepts a
DateTime