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

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Date and time library

Time point
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day (C++20)
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weekday (C++20)
operator/ (C++20)
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year_month_weekday (C++20)
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weekday_indexed (C++20)
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month_weekday (C++20)
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std::chrono::weekday

Member functions
weekday::weekday
weekday::operator++weekday::operator--
weekday::operator+=weekday::operator-=
weekday::c_encodingweekday::iso_encoding
weekday::ok
weekday::operator[]
Nonmember functions
operator==
operator+operator-
operator<<
from_stream
Helper classes
formatter<std::chrono::weekday>
formatter<std::chrono::hash> (C++26)

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Defined in header`<chrono>`
constexprstd::chrono::weekday operator+(conststd::chrono::weekday& wd, conststd::chrono::days& d)noexcept;	(1)	(since C++20)
constexprstd::chrono::weekday operator+(conststd::chrono::days& d, conststd::chrono::weekday& wd)noexcept;	(2)	(since C++20)
constexprstd::chrono::weekday operator-(conststd::chrono::weekday& wd, conststd::chrono::days& d)noexcept;	(3)	(since C++20)
constexprstd::chrono::days operator-(conststd::chrono::weekday& wd1, conststd::chrono::weekday& wd2)noexcept;	(4)	(since C++20)

1,2) Addsd.count() days towd. The weekday value held in the result is computed by first evaluatingstatic_cast<longlong>(wd.c_encoding())+ d.count() and reducing it modulo 7 to an integer in the range[0, 6].

3) Subtractsd.count() days fromwd. Equivalent toreturn wd+-d;.

4) Ifwd1.ok() andwd2.ok() are bothtrue, returns astd::chrono::days valued such thatd.count() is in the range[0, 6] andwd2+ d== wd1. Otherwise the returned value is unspecified.

[edit]Return value

1-3) Astd::chrono::weekday holding a weekday value calculated as described above.

4) Astd::chrono::days representing the distance betweenwd1 andwd2.

[edit]Notes

As long as the computation doesn't overflow,(1-3) always return a validweekday even ifwd.ok() isfalse.

[edit]Example

Run this code

#include <chrono>#include <iostream> int main(){std::cout<<std::boolalpha; std::chrono::weekday wd{4};    wd= wd+std::chrono::days(2);std::cout<<(wd==std::chrono::weekday(6))<<' '<<(wd==std::chrono::Saturday)<<' ';     wd= wd-std::chrono::days(3);std::cout<<(wd==std::chrono::weekday(3))<<' '<<(wd==std::chrono::Wednesday)<<' ';     wd=std::chrono::Tuesday;    wd= wd+std::chrono::days{8};// (((2 + 8) == 10) % 7) == 3;std::cout<<(wd==std::chrono::Wednesday)<<' ';     wd= wd+(std::chrono::Sunday-std::chrono::Thursday);// (3 + 3) == 6std::cout<<(wd==std::chrono::Saturday)<<'\n';}

Output:

true true true true true true

[edit]See also

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

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

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