The following code gives an error for the time_from_string function (from_time_t works just fine):
 
using namespace boost::posix_time;
ptime epoch = from_time_t(0);
ptime other = time_from_string("2011-08-09 17:27:00.000000");
 
The error is:
 
main.obj:-1: error: LNK2019: unresolved external symbol "public: static class boost::shared_ptr<class std::map<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,unsigned short,struct std::less<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >,class std::allocator<struct std::pair<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const ,unsigned short> > > > __cdecl boost::gregorian::greg_month::get_month_map_ptr(void)" (?get_month_map_ptr@greg_month@gregorian@boost@@SA?AV?$shared_ptr@V?$map@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@GU?$less@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@V?$allocator@U?$pair@$$CBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@G@std@@@2@@std@@@3@XZ) referenced in function "unsigned short __cdecl boost::date_time::month_str_to_ushort<class boost::gregorian::greg_month>(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??$month_str_to_ushort@Vgreg_month@gregorian@boost@@@date_time@boost@@YAGAEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z)
 
I’m using Qt Creator, along with Visual Studio 2015. I have the installed the windows binary of boost 1.61.1 .