std::chrono::operator+, std::chrono::operator- (std::chrono::day)

 

C++

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Freestanding and hosted

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

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Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

Technical specifications

Symbols index

External libraries

 

Date and time library

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) is_clock (C++20) utc_clock (C++20) tai_clock (C++20) high_resolution_clock (C++11) 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)

Calendar 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) chrono I/O parse (C++20)

Time zone tzdb (C++20) tzdb_list (C++20) get_tzdbget_tzdb_listreload_tzdbremote_version (C++20)(C++20)(C++20)(C++20) sys_info (C++20) local_info (C++20) nonexistent_local_time (C++20) ambiguous_local_time (C++20) locate_zone (C++20) current_zone (C++20) time_zone (C++20) choose (C++20) zoned_traits (C++20) zoned_time (C++20) time_zone_link (C++20) leap_second (C++20) leap_second_info (C++20) get_leap_second_info (C++20) C-style date and time

 

std::chrono::day

Member functions

day::day

day::operator++day::operator--

day::operator+=day::operator-=

day::operator unsigned

day::ok

Nonmember functions

operator==operator<=>

operator+operator-

operator<<

from_stream

operator""d

Helper classes

formatter<std::chrono::day>

hash<std::chrono::day> (C++26)

 

Defined in header <chrono>
constexpr std::chrono::day operator+( const std::chrono::day& d, const std::chrono::days& ds ) noexcept;	(1)	(since C++20)
constexpr std::chrono::day operator+( const std::chrono::days& ds, const std::chrono::day& d ) noexcept;	(2)	(since C++20)
constexpr std::chrono::day operator-( const std::chrono::day& d, const std::chrono::days& ds ) noexcept;	(3)	(since C++20)
constexpr std::chrono::days operator-( const std::chrono::day& x, const std::chrono::day& y ) noexcept;	(4)	(since C++20)

1,2) Adds ds.count() days to d.

3) Subtracts ds.count() days from d.

4) Calculate the difference, in days, between two day x and y.

Return value

1,2) std::chrono::day(unsigned(d) + ds.count())

3) std::chrono::day(unsigned(d) - ds.count())

4) std::chrono::days(int(unsigned(x)) - int(unsigned(y)))

Notes

1-3) If the result would be outside the range [0, 255], the actual stored value is unspecified.

Example

Run this code

#include <cassert>
#include <chrono>

int main()
{
    std::chrono::day d{15};

    d = d + std::chrono::days(2);
    assert(d == std::chrono::day(17));

    d = d - std::chrono::days(3);
    assert(d == std::chrono::day(14));

    constexpr std::chrono::days ds = std::chrono::day(16) - std::chrono::day(14);
    static_assert(ds == std::chrono::days(2));
}

See also

operator++operator++(int)operator--operator--(int)	increments or decrements the day (public member function)
operator+=operator-=	adds or subtracts a number of days (public member function)