std::time_get::get_time,std::time_get::do_get_time(3)

NAME
std::time_get::get_time,std::time_get::do_get_time - std::time_get::get_time,std::time_get::do_get_time

Synopsis
   Defined in header <locale>
   public:
   iter_type get_time( iter_type beg, iter_type end, std::ios_base& str, (1)
   std::ios_base::iostate& err, std::tm* t) const;
   protected:
   virtual iter_type do_get_time( iter_type beg, iter_type end, std::ios_base& (2)
   str,
   std::ios_base::iostate& err, std::tm* t) const;
   1) public member function, calls the protected virtual member function do_get_time
   of the most derived class.
   2) Reads successive characters from the sequence [beg, end) and parses out the time
   value following the same rules as the format specifier
   "%X"
   (until C++11)
   "%H:%M:%S"
   (since C++11) as used by the functions std::get_time, time_get::get, and the POSIX
   function strptime().
                        The parsed time is stored in the corresponding fields of the
                        std::tm structure pointed to by the argument t.
                        If the end iterator is reached before a valid value is read,
                        the function sets std::ios_base::eofbit in err. If a parsing
                        error is encountered, the function sets std::ios_base::failbit
                        in err.

Parameters
   beg - iterator designating the start of the sequence to parse
   end - one past the end iterator for the sequence to parse
   str - a stream object that this function uses to obtain locale facets when needed,
         e.g. std::ctype to skip whitespace
   err - stream error flags object that is modified by this function to indicate errors
   t - pointer to the std::tm object that will hold the result of this function call

Return value
   Iterator pointing one past the last character in [beg, end) that was recognized as a
   part of a valid date.

Notes
   For the alphabetic components of the default time format (if any), this function is
   usually case-insensitive.
   If a parsing error is encountered, most implementations of this function leave *t
   unmodified.

Example
// Run this code
 #include <iostream>
 #include <locale>
 #include <sstream>
 #include <iterator>
 void try_get_time(const std::string& s)
 {
     std::cout << "Parsing the time out of '" << s <<
                  "' in the locale " << std::locale().name() << '\n';
     std::istringstream str(s);
     std::ios_base::iostate err = std::ios_base::goodbit;
     std::tm t;
     std::istreambuf_iterator<char> ret =
         std::use_facet<std::time_get<char>>(str.getloc()).get_time(
             {str}, {}, str, err, &t
         );
     str.setstate(err);
     if(str) {
         std::cout << "Hours: " << t.tm_hour << ' '
                   << "Minutes: " << t.tm_min << ' '
                   << "Seconds: " << t.tm_sec << '\n';
     } else {
         std::cout << "Parse failed. Unparsed string: ";
         std::copy(ret, {}, std::ostreambuf_iterator<char>(std::cout));
         std::cout << '\n';
     }
 }
 int main()
 {
     std::locale::global(std::locale("ru_RU.utf8"));
     try_get_time("21:40:11");
     try_get_time("21-40-11");
     std::locale::global(std::locale("ja_JP.utf8"));
     try_get_time("21時37分58秒");
 }

Output:
 Parsing the time out of '21:40:11' in the locale ru_RU.utf8
 Hours: 21 Minutes: 40 Seconds: 11
 Parsing the time out of '21-40-11' in the locale ru_RU.utf8
 Parse failed. Unparsed string: -40-11
 Parsing the time out of '21時37分58秒' in the locale ja_JP.utf8
 Hours: 21 Minutes: 37 Seconds: 58

See also
   get_time parses a date/time value of specified format
   (C++11) (function template)