std::get_time

From cppreference.com
< cpplrm; | iolrm; | manip
C++
Input/output library
Input/output manipulators
Floating-point formatting
Integer formatting
Boolean formatting
Field width and fill control
Other formatting
Whitespace processing
Output flushing
Status flags manipulation
Time and money I/O
(C++11)
get_time
(C++11)
(C++11)
(C++11)
Quoted manipulator
(C++14)
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.23 (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. 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. (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. 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. 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. 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 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. 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. 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. 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. 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. 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 23 (year Heisei 23) instead of 2011 (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 23 (year Heisei 23) instead of 2011 (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

See also

 parses time/date values from an input character sequence into struct std::tm
(class template)
(C++11)
 formats and outputs a date/time value according to the specified format
(function template)
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/io/manip/get_time&oldid=94812"