std::chrono::year_month_weekday::operator+=, std::chrono::year_month_weekday::operator-=
constexpr std::chrono::year_month_weekday& operator+=(const std::chrono::years& dy) const noexcept; | (1) | (since C++20) |
constexpr std::chrono::year_month_weekday& operator+=(const std::chrono::months& dm) const noexcept; | (2) | (since C++20) |
constexpr std::chrono::year_month_weekday& operator-=(const std::chrono::years& dy) const noexcept; | (3) | (since C++20) |
constexpr std::chrono::year_month_weekday& operator-=(const std::chrono::months& dm) const noexcept; | (4) | (since C++20) |
Modifies the time point *this represents by the duration dy or dm.
1) Equivalent to
*this = *this + dy;
2) Equivalent to
*this = *this + dm;
3) Equivalent to
*this = *this - dy;
4) Equivalent to
*this = *this - dm;
Notes
Durations that are convertible to std::chrono::months, but not std::chrono::years, can be directly added to or subtracted from a year_month_weekday. Durations convertible to std::chrono::years cannot because such durations are also convertible to std::chrono::months, resulting in an ambiguity:
using namespace std::chrono;
using decades = duration<int, std::ratio_multiply<std::ratio<10>, years::period>>;
using kilomonths = duration<int, std::ratio_multiply<std::kilo, months::period>>;
auto ymwd = 2001y/April/Sunday[1];
ymwd += decades{1}; // error, ambiguous
ymwd += kilomonths{1}; // OKSee also
adds or subtracts a year_month_weekday and some number of years or months (function) |
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