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

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< cpp‎ | chrono‎ | year

constexpr std::chrono::year& operator+=( const std::chrono::years& y ) noexcept; | (1) | (since C++20)
constexpr std::chrono::year& operator-=( const std::chrono::years& y ) noexcept; | (2) | (since C++20)

Adds or subtracts y.count() years from the year value.

1) Equivalent to *this = *this + y;
2) Equivalent to *this = *this - y;

### Return value

A reference to this `year` after modification.

### Notes

If the result would be outside the range [-32767, 32767], the actual stored value is unspecified.

### Example

Run this code

    #include <iostream>
    #include <chrono>

    int main()
    {
        using namespace std::literals::chrono_literals;
        std::cout << std::boolalpha;

        std::chrono::year y {2020};

        y += std::chrono::years(12);
        std::cout << (y == 2032y) << ' ';

        y -= std::chrono::years(33);
        std::cout << (y == 1999y) << '\n';
    }

Output:

    true true

### See also

operator++operator++(int)operator--operator--(int) | increments or decrements the year (public member function)
operator+operator- (C++20) | performs arithmetic on `year`s (function)

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