std::get_time

 

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

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
fmt	-	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 specifier Explanation Writes to fields % 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 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 required tm_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 locale all 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

An object of unspecified type such that

• if in is an object of type std::basic_istream<CharT, Traits>, the expression in >> get_time(tmb, fmt)
  • has type std::basic_istream<CharT, Traits>&
  • has value in
  • behaves as if it called f(in, tmb, fmt)

where the function f is defined as:

template<class CharT, class Traits>
void f(std::basic_ios<CharT, Traits>& str, std::tm* tmb, const CharT* fmt)
{
    using Iter = std::istreambuf_iterator<CharT, Traits>;
    using TimeGet = time_get<CharT, Iter>;
 
    std::ios_base::iostate err = std::ios_base::goodbit;
    const TimeGet& tg = std::use_facet<TimeGet>(str.getloc());
 
    tg.get(Iter(str.rdbuf()), Iter(), str, err, tmb,
        fmt, fmt + Traits::length(fmt));
 
    if (err != std::ios_base::goodbit)
        str.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 or gcc >= 12.1 to observe the output. libstdc++ before 12.1 does not correctly implement the %b specifier: bug #78714.

Run this code

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

See also

time_get	parses time/date values from an input character sequence into std::tm (class template)
put_time (C++11)	formats and outputs a date/time value according to the specified format (function template)
parse (C++20)	parses a chrono object from a stream (function template)