std::tm

 

C++

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Freestanding and hosted

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Feature test macros (C++20)

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Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Dynamic memory management Program utilities Coroutine support (C++20) Variadic functions is_constant_evaluated (C++20) launder (C++17) initializer_list (C++11) source_location (C++20) Three-way comparison (C++20) three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)    is_eqis_neqis_ltis_lteqis_gtis_gteq (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

General utilities Date and time Function objects Formatting library (C++20) bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator> rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)    cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17)

 

Date and time utilities

Time point
time_point (C++11)	clock_time_conversion (C++20)	clock_cast (C++20)
Duration
duration (C++11)
Clocks
system_clock (C++11) steady_clock (C++11) high_resolution_clock (C++11)	is_clock (C++20) utc_clock (C++20) tai_clock (C++20)	gps_clock (C++20) file_clock (C++20) local_t (C++20)
Time of day
is_amis_pm (C++20)(C++20)	make12make24 (C++20)(C++20)	hh_mm_ss (C++20)
Calendars
day (C++20) month (C++20) year (C++20) weekday (C++20) operator/ (C++20) year_month_day (C++20)	year_month_day_last (C++20) year_month_weekday (C++20) year_month_weekday_last (C++20)       weekday_indexed (C++20) weekday_last (C++20) month_day (C++20)	month_day_last (C++20) month_weekday (C++20) month_weekday_last (C++20) year_month (C++20) last_speclast (C++20)(C++20)
Time zones
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chrono I/O
parse (C++20)
C-style date and time

 

C-style date and time utilities

Functions

Time manipulation

difftime

time

clock

timespec_get (C++17)

Format conversions

asctime

ctime

strftime

wcsftime

gmtime

localtime

mktime

Constants

CLOCKS_PER_SEC

Types

tm

time_t

clock_t

timespec (C++17)

 

Defined in header <ctime>
struct tm;

Structure holding a calendar date and time broken down into its components.

Member objects

int tm_sec	seconds after the minute – [0, 61] (until C++11)[0, 60] (since C++11) (public member object)
int tm_min	minutes after the hour – [0, 59] (public member object)
int tm_hour	hours since midnight – [0, 23] (public member object)
int tm_mday	day of the month – [1, 31] (public member object)
int tm_mon	months since January – [0, 11] (public member object)
int tm_year	years since 1900 (public member object)
int tm_wday	days since Sunday – [0, 6] (public member object)
int tm_yday	days since January 1 – [0, 365] (public member object)
int tm_isdst	Daylight Saving Time flag. The value is positive if DST is in effect, zero if not and negative if no information is available (public member object)

Notes

The Standard mandates only the presence of the aforementioned members in either order. The implementations usually add more data-members to this structure.

Example

Show the start of calendar time.

Run this code

#include <ctime>
#include <iostream>
 
int main()
{
    std::tm start{};
    start.tm_mday = 1;
 
    std::mktime(&start);
    std::cout << std::asctime(&start)
              << "sizeof(std::tm) = "
              << sizeof(std::tm) << '\n';
}

Possible output:

Mon Jan  1 00:00:00 1900
sizeof(std::tm) = 56

See also

localtime	converts time since epoch to calendar time expressed as local time (function)
gmtime	converts time since epoch to calendar time expressed as Universal Coordinated Time (function)