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

 

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C 样式日期和时间

 

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

修改时间点 *this 表示的持续时间 dy 或 dm.

1) 等效于 *this = *this + dy;.

2) 等效于 *this = *this + dm;.

3) 等效于 *this = *this - dy;.

4) 等效于 *this = *this - dm;.

对于可转换为 std::chrono::years 和 std::chrono::months 的持续时间，如果调用在其他情况下会导致歧义，则 years 重载 (1,3) 优先。

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]

另请参阅

operator+operator- (C++20)

添加或减去 year_month_weekday 和一些年或月 (函数)