std::get_time (3) - Linux Manuals

std::get_time: std::get_time

NAME

std::get_time - std::get_time

Synopsis

Defined in header <iomanip>
template< class CharT > (since C++11)
/*unspecified*/ get_time( std::tm* tmb, const CharT* fmt );

When used in an expression in >> get_time(tmb, fmt), parses the character input as a date/time value according to format string fmt according to the std::time_get facet of the locale currently imbued in the input stream in. The resultant value is stored in a std::tm object pointed to by tmb.

Parameters

tmb - valid pointer to the std::tm object where the result will be stored
      pointer to a null-terminated CharT string specifying the conversion format
      The format string consists of zero or more conversion specifiers, whitespace characters, and ordinary characters (except %). Each ordinary character is expected to match one character in the input stream in case-insensitive comparison. Each whitespace character matches arbitrary whitespace in the input string. Each conversion specification begins with % character, optionally followed by E or O modifier (ignored if unsupported by the locale), followed by the character that determines the behavior of the specifier. The format specifiers match the POSIX function strptime():

      Conversion Explanation Writes to fields
      specifier
      % matches a literal %. The full conversion specification must be %%. (none)
      t matches any whitespace. (none)
      n matches any whitespace. (none)
      Year
      Y parses full year as a 4 digit decimal number, leading zeroes permitted but not required tm_year
      EY parses year in the alternative representation, e.g.平成23年 (year Heisei 23) which writes 2011 to tm_year in ja_JP locale tm_year
      y parses last 2 digits of year as a decimal number. Range [69,99] results in values 1969 to 1999, range [00,68] results in 2000-2068 tm_year
      Oy parses last 2 digits of year using the alternative numeric system, e.g. 十一 is parsed as 11 in ja_JP locale tm_year
      Ey parses year as offset from locale's alternative calendar period %EC tm_year
      C parses the first 2 digits of year as a decimal number (range [00,99]) tm_year
      EC parses the name of the base year (period) in the locale's alternative representation, e.g. 平成 (Heisei era) in ja_JP tm_year
      Month
      b parses the month name, either full or abbreviated, e.g. Oct tm_mon
      h synonym of b tm_mon
      B synonym of b tm_mon
      m parses the month as a decimal number (range [01,12]), leading zeroes permitted but not required tm_mon
      Om parses the month using the alternative numeric system, e.g. 十二 parses as 12 in ja_JP locale tm_mon
      Week
      U parses the week of the year as a decimal number (Sunday is the first day of the week) (range [00,53]), leading zeroes permitted but not required tm_year, tm_wday, tm_yday
      OU parses the week of the year, as by %U, using the alternative numeric system, e.g. 五十二 parses as 52 in ja_JP locale tm_year, tm_wday, tm_yday
      W parses the week of the year as a decimal number (Monday is the first day of the week) (range [00,53]), leading zeroes permitted but not required tm_year, tm_wday, tm_yday
      OW parses the week of the year, as by %W, using the alternative numeric system, e.g. 五十二 parses as 52 in ja_JP locale tm_year, tm_wday, tm_yday
      Day of the year/month
      j parses day of the year as a decimal number (range [001,366]), leading zeroes permitted but not required tm_yday
      d parses the day of the month as a decimal number (range [01,31]), leading zeroes permitted but not required tm_mday
fmt - Od parses the day of the month using the alternative numeric system, e.g 二十七 parses as 27 in ja_JP locale, leading zeroes permitted but not reqtm_mday
      e synonym of d tm_mday
      Oe synonym of Od tm_mday
      Day of the week
      a parses the name of the day of the week, either full or abbreviated, e.g. Fri tm_wday
      A synonym of a tm_wday
      w parses weekday as a decimal number, where Sunday is 0 (range [0-6]) tm_wday
      Ow parses weekday as a decimal number, where Sunday is 0, using the alternative numeric system, e.g. 二 parses as 2 in ja_JP locale tm_wday
      Hour, minute, second
      H parses the hour as a decimal number, 24 hour clock (range [00-23]), leading zeroes permitted but not required tm_hour
      OH parses hour from 24-hour clock using the alternative numeric system, e.g. 十八 parses as 18 in ja_JP locale tm_hour
      I parses hour as a decimal number, 12 hour clock (range [01,12]), leading zeroes permitted but not required tm_hour
      OI parses hour from 12-hour clock using the alternative numeric system, e.g. 六 reads as 06 in ja_JP locale tm_hour
      M parses minute as a decimal number (range [00,59]), leading zeroes permitted but not required tm_min
      OM parses minute using the alternative numeric system, e.g. 二十五 parses as 25 in ja_JP locale tm_min
      S parses second as a decimal number (range [00,60]), leading zeroes permitted but not required tm_sec
      OS parses second using the alternative numeric system, e.g. 二十四 parses as 24 in ja_JP locale tm_sec

Other

      c parses the locale's standard date and time string format, e.g. Sun Oct 17 04:41:13 2010 (locale dependent) all
      Ec parses the locale's alternative date and time string format, e.g. expecting 平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP lallle
      x parses the locale's standard date representation all
      Ex parses the locale's alternative date representation, e.g. expecting 平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale all
      X parses the locale's standard time representation all
      EX parses the locale's alternative time representation all
      D equivalent to "%m / %d / %y " tm_mon, tm_mday, tm_year
      r parses locale's standard 12-hour clock time (in POSIX, "%I : %M : %S %p") tm_hour, tm_min, tm_sec
      R equivalent to "%H : %M" tm_hour, tm_min
      T equivalent to "%H : %M : %S" tm_hour, tm_min, tm_sec
      p parses the locale's equivalent of a.m. or p.m. tm_hour

      Note: tm_isdst is not written to, and needs to be set explicitly for use with functions such as mktime

Return value

Returns an object of unspecified type such that if in is the name of an input stream of type std::basic_istream<CharT, Traits>, then the expression in >> get_time(tmb, fmt) behaves as if the following code was executed:
typedef std::istreambuf_iterator<CharT, Traits> Iter;
typedef std::time_get<CharT, Iter> TimeGet;
std::ios_base::iostate err = std::ios_base::goodbit;
const TimeGet& tg = std::use_facet<TimeGet>(in.getloc());
tg.get(Iter(in.rdbuf()), Iter(), in, err, tmb, fmt, fmt + traits::length(fmt));
if (err != std::ios_base::goodbit)
in.setstate(err);

Notes

As specified in std::time_get::do_get, which this function calls, it's unspecified if this function zero out the fields in *tmb that are not set directly by the conversion specifiers that appear in fmt: portable programs should initialize every field of *tmb to zero before calling std::get_time.

Example

note: choose clang to observe the output. libstdc++ does not correctly implement the %b specifier: bug_78714
// Run this code

  #include <iostream>
  #include <sstream>
  #include <locale>
  #include <iomanip>

  int main()
  {
      std::tm t = {};
      std::istringstream ss("2011-Februar-18 23:12:34");
      ss.imbue(std::locale("de_DE.utf-8"));
      ss >> std::get_time(&t, "%Y-%b-%d %H:%M:%S");
      if (ss.fail()) {
          std::cout << "Parse failed\n";
      } else {
          std::cout << std::put_time(&t, "%c") << '\n';
      }
  }

Possible output:

  Sun Feb 18 23:12:34 2011