Sorry for being a bit of a douche, but I find the formatting options in date_time lacking and would like to see what others think. We have a use case that I think displays some of the shortcomings. We have a time duration stored as an int representing the number of miliseconds. When displaying the time duration we want to use MM:SS,FFF, padding with 0s in order to get them to line up nicely. First problem here is it's not possible to control the number of fractions, we use substr to remove the last 3 unwanted digits, this however naturally doesn't respect rounding. The second problem is that it doesn't seem to be possible to control the padding, ( although this isn't a problem for our use case ). Another problem is that it doesn't seem to be possible to format a time_duration directly, the only solution which I've been able to find is to construct an arbitrary valid date and keep the time part at zero. This seems both unnecessary and imposes restrictions if one were interested in actually measuring and format long durations of time. I also think formatting a date time is often unnecessary verbose. I would personally appreciate formatting functionality along the lines of: // Apply formating_string to duration using supplied locale std::string format_time_duration( const boost::posix_time::time_duration& duration, const std::string& formating_string, const std::locale& locale = std::locale::classic() ); For reference, this is how we format our times: std::string format_highscore( unsigned int miliseconds ) {        boost::posix_time::time_duration td = boost::posix_time::milliseconds( 10004 );        boost::posix_time::ptime pt( ( boost::gregorian::date( 2000, 1, 1 ) ) );        pt += td;        std::stringstream ss;        boost::posix_time::time_facet* df( new boost::posix_time::time_facet( "%M:%S,%f" ) );        ss.imbue( std::locale( ss.getloc(), df ) );        ss << pt;        std::string ret = ss.str();        ret = ret.substr( 0, ret.size() - 3 );        return ret; }