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

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< cpp ‎ | chrono ‎ | day
C++
Date and time library
std::chrono::day
定义于头文件 <chrono>
constexpr std:: chrono :: day operator + ( const std:: chrono :: day & d,
const std:: chrono :: days & ds ) noexcept ;
(1) (C++20 起)
constexpr std:: chrono :: day operator + ( const std:: chrono :: days & ds,
const std:: chrono :: day & d ) noexcept ;
(2) (C++20 起)
constexpr std:: chrono :: day operator - ( const std:: chrono :: day & d,
const std:: chrono :: days & ds ) noexcept ;
(3) (C++20 起)
constexpr std:: chrono :: days operator - ( const std:: chrono :: day & x,
const std:: chrono :: day & y ) noexcept ;
(4) (C++20 起)
1,2) 向 d 添加 ds. count ( ) 天。
3) 从 d 中减去 ds. count ( ) 天。
4) 计算两个 day x 与 y 之间相差的天数。

目录

返回值

1,2) std:: chrono :: day ( unsigned ( d ) + ds. count ( ) )
3) std:: chrono :: day ( unsigned ( d ) - ds. count ( ) )
4) std:: chrono :: days ( int ( unsigned ( x ) ) - int ( unsigned ( y ) ) )

注释

1-3) 若结果超出范围 [ ​ 0 ​ , 255 ] ，实际存储的值是未指定的。

示例

运行此代码 
#include <cassert>
#include <chrono>
int main()
{
    std::chrono::day d{15};
    d = d + std::chrono::days(2);
    assert(d == std::chrono::day(17));
    d = d - std::chrono::days(3);
    assert(d == std::chrono::day(14));
    constexpr std::chrono::days ds = std::chrono::day(16) - std::chrono::day(14);
    static_assert(ds == std::chrono::days(2));
}

参见

递增或递减日期值
(公开成员函数)
增加或减少指定天数
(公开成员函数)