std::chrono::year:: operator+, std::chrono::year:: operator-

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std::chrono::year
constexpr std:: chrono :: year operator + ( ) noexcept ;
(1) (since C++20)
constexpr std:: chrono :: year operator - ( ) noexcept ;
(2) (since C++20)

Applies the unary operators to the year value.

1) Returns a copy of * this .
2) Returns a year whose year value is the negation of that of * this .

Return value

1) * this
2) std:: chrono :: year ( - int ( * this ) )

Example

Run this code 
#include <chrono>
#include <iostream>
 
int main()
{
    constexpr std::chrono::year y{2020};
    constexpr auto ny = -y;
    std::cout << "The year " << (int)y << " negated is " << (int)ny << '\n';
}

Output: 

The year 2020 negated is -2020
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