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

constexpr std::chrono::weekday operator+(const std::chrono::weekday& wd,
                                         const std::chrono::days& d) noexcept;
 (1) (since C++20) 
constexpr std::chrono::weekday operator+(const std::chrono::days& d,
                                         const std::chrono::weekday& wd) noexcept;
 (2) (since C++20) 
constexpr std::chrono::weekday operator-(const std::chrono::weekday& wd, 
                                         const std::chrono::days& d) noexcept;
 (3) (since C++20) 
constexpr std::chrono::days operator-(const std::chrono::weekday& wd1, 
                                      const std::chrono::weekday& wd2) noexcept;
 (4) (since C++20)
1-2) Adds d.count() days to wd. The weekday value held in the result is computed by first evaluating static_cast<long long>(unsigned(wd)) + d.count() and reducing it modulo 7 to an integer in the range [0, 6].
3) Subtracts d.count() days from wd. Equivalent to return wd + -d;
4) If wd1.ok() and wd2.ok() are both true, returns a std::chrono::days value d such that d.count() is in the range [0, 6] and wd2 + d == wd1. Otherwise the returned value is unspecified.

Return value

1-3) A std::chrono::weekday holding a weekday value calculated as described above.
4) A std::chrono::days representing the distance between wd1 and wd2.

Notes

As long as the computation doesn't overflow, (1-3) always return a valid weekday even if wd.ok() is false.

Example

See also

increments or decrements the weekday
(public member function)
adds or subtracts a number of days
(public member function)

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