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

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< cpp‎ | chrono‎ | year month weekday

constexpr std::chrono::year_month_weekday& operator+=( const std::chrono::years& dy ) const noexcept; | (1) | (since C++20)
constexpr std::chrono::year_month_weekday& operator+=( const std::chrono::months& dm ) const noexcept; | (2) | (since C++20)
constexpr std::chrono::year_month_weekday& operator-=( const std::chrono::years& dy ) const noexcept; | (3) | (since C++20)
constexpr std::chrono::year_month_weekday& operator-=( const std::chrono::months& dm ) const noexcept; | (4) | (since C++20)

Modifies the time point *this represents by the duration `dy` or `dm`.

1) Equivalent to *this = *this + dy;
2) Equivalent to *this = *this + dm;
3) Equivalent to *this = *this - dy;
4) Equivalent to *this = *this - dm;

For durations that are convertible to both std::chrono::years and std::chrono::months, the `years` overloads (1,3) are preferred if the call would otherwise be ambiguous.

### Example

Run this code

    #include <iostream>
    #include <chrono>

    int main()
    {
        std::cout << std::boolalpha;

        auto ymwi {1/std::chrono::Wednesday[2]/2021};
        ymwi += std::chrono::years(5);
        std::cout << (static_cast<std::chrono::year_month_day>(ymwi) ==
                                  std::chrono::year(2026)/1/14) << ' ';
        ymwi -= std::chrono::months(1);
        std::cout << (static_cast<std::chrono::year_month_day>(ymwi) ==
                                  std::chrono::day(10)/12/2025) << '\n';
    }

Output:

    true true

### See also

operator+operator- (C++20) | adds or subtracts a `year_month_weekday` and some number of years or months (function)

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