std::chrono::year_month_weekday::operator+=, std::chrono::year_month_weekday::operator-=

 

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std::chrono::year_month_weekday

成员函数

year_month_weekday::year_month_weekday

year_month_weekday::operator+=year_month_weekday::operator-=

year_month_weekday::yearyear_month_weekday::monthyear_month_weekday::weekdayyear_month_weekday::indexyear_month_weekday::weekday_indexed

year_month_weekday::operator sys_daysyear_month_weekday::operator local_days

year_month_weekday::ok

非成员函数

operator==

operator+operator-

operator<<

辅助类

formatter<std::chrono::year_month_weekday>

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

 

constexpr std::chrono::year_month_weekday&     operator+=( const std::chrono::years& dy ) const noexcept;	(1)	(C++20 起)
constexpr std::chrono::year_month_weekday&     operator+=( const std::chrono::months& dm ) const noexcept;	(2)	(C++20 起)
constexpr std::chrono::year_month_weekday&     operator-=( const std::chrono::years& dy ) const noexcept;	(3)	(C++20 起)
constexpr std::chrono::year_month_weekday&     operator-=( const std::chrono::months& dm ) const noexcept;	(4)	(C++20 起)

以时长 dy 或 dm 为程度修改 *this 表示的时间点。

1) 等价于 *this = *this + dy;。

2) 等价于 *this = *this + dm;。

3) 等价于 *this = *this - dy;。

4) 等价于 *this = *this - dm;。

对于能转换到 std::chrono::years 与 std::chrono::months 两者的时长，若调用有歧义，则偏好 years 的重载 (1,3)。

示例

运行此代码

#include <cassert>
#include <chrono>
#include <iostream>
 
int main()
{
    auto ymwi{1/std::chrono::Wednesday[2]/2021};
    std::cout << ymwi << '\n';
 
    ymwi += std::chrono::years(5);
    std::cout << ymwi << '\n';
    assert(static_cast<std::chrono::year_month_day>(ymwi) ==
                       std::chrono::year(2026)/1/14);
 
    ymwi -= std::chrono::months(1);
    std::cout << ymwi << '\n';
    assert(static_cast<std::chrono::year_month_day>(ymwi) == 
                       std::chrono::day(10)/12/2025);
}

输出：

2021/Jan/Wed[2]
2026/Jan/Wed[2]
2025/Dec/Wed[2]

参阅

operator+operator- (C++20)

将 year_month_weekday 与一定数量的 years 或 months 相加或相减 (函数)