std::chrono::is_am, std::chrono::is_pm, std::chrono::make12, std::chrono::make24

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Utilities library

Language support Type support (basic types, RTTI, type traits) Library feature-test macros (C++20) Dynamic memory management Program utilities Error handling Coroutine support (C++20) Variadic functions 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) integer_sequence (C++14) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_not_equalcmp_lesscmp_greatercmp_less_thancmp_greater_than (C++20)(C++20)(C++20)(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) forward (C++11) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) apply (C++17) make_from_tuple (C++17) optional (C++17) any (C++17) variant (C++17) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17)

 

Date and time utilities

duration (C++11) time_point (C++11)	clock_time_conversion (C++20) clock_cast (C++20)
Time of day
hh_mm_ss (C++20)	is_amis_pmmake12make24 (C++20)(C++20)(C++20)(C++20)
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)
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)
Time zones
tzdb (C++20) tzdb_list (C++20) get_tzdbget_tzdb_listreload_tzdbremote_version (C++20)(C++20)(C++20)(C++20)	time_zone (C++20) locate_zone (C++20) current_zone (C++20) zoned_time (C++20) time_zone_link (C++20) leap_second (C++20)
C-style date and time

 

Defined in header <chrono>
constexpr bool is_am( const std::chrono::hours& h ) noexcept;	(1)	(since C++20)
constexpr bool is_pm( const std::chrono::hours& h ) noexcept;	(2)	(since C++20)
constexpr std::chrono::hours make12( const std::chrono::hours& h ) noexcept;	(3)	(since C++20)
constexpr std::chrono::hours make24( const std::chrono::hours& h,                                      bool is_pm ) noexcept;	(4)	(since C++20)

These functions aid in translating between a 12-hour format time of day, and a 24-hour format time of day.

1) Detects whether the 24-hour format time is a.m. (ante meridiem, before midday).

2) Detects whether the 24-hour format time is p.m. (post meridiem, after midday).

3) Returns the 12-hour equivalent of a 24-hour format time.

4) Returns the 24-hour equivalent of a 12-hour format time h, where is_pm determines whether the time is p.m.

Parameters

h	-	12-hour or 24-hour format time to detect
is_pm	-	whether the 12-hour format time is p.m.

Return value

1) 0h <= h && h <= 11h.

2) 12h <= h && h <= 23h.

3) If h is in range [0h, 23h], returns the 12-hour equivalent in range [1h, 12h]. Otherwise, the return value is unspecified.

4) If h is in range [1h, 12h], returns the 24-hour equivalent in range [0h, 11h] if is_pm is false, or in range [12h, 23h] otherwise. Otherwise, the return value is unspecified.