std::chrono::year:: is_leap

判断 * this 是否表示 公历推前历法 中的闰年。

* this 表示闰年，如果存储的年份值满足以下条件：

• 能被4整除但不能被100整除；或
• 能被400整除。

返回值

若 * this 表示闰年则为 true ，否则为 false 。

示例

#include <chrono>
#include <iostream>
int main()
{
    using namespace std::chrono_literals;
    for (const std::chrono::year y : {2020y, 2021y, 2000y, 3000y})
    {
        if (const int iy{static_cast<int>(y)}; y.is_leap())
            std::cout << iy << " is a leap year because it is divisible by "
                      << (iy % 400 == 0 ? "400\n" : "4 and not divisible by 100\n");
        else
            std::cout << iy << " is not a leap year\n";
    }
}

2020 is a leap year because it is divisible by 4 and not divisible by 100
2021 is not a leap year
2000 is a leap year because it is divisible by 400
3000 is not a leap year