constexpr bool is_leap() const noexcept; | (since C++20) |

Determines if `*this`

represents a leap year in the proleptic Gregorian calendar.

`*this`

represents a leap year if the stored year value.

- is divisible by 4 and not divisible by 100; or
- is divisible by 400.

`true`

if `*this`

represents a leap year, otherwise `false`

.

#include <iostream> #include <chrono> 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"; } } }

Output:

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

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