std::chrono::year_month::operator+=, std::chrono::year_month::operator-=

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< cpp‎ | chrono‎ | year month

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C-style date and time
std::chrono::year_month
constexpr std::chrono::year_month &
    operator+ = ( const std::chrono::years & dy ) const noexcept ;
(1) (since C++20)
constexpr std::chrono::year_month &
    operator+ = ( const std::chrono::months & dm ) const noexcept ;
(2) (since C++20)
constexpr std::chrono::year_month &
    operator- = ( const std::chrono::years & dy ) const noexcept ;
(3) (since C++20)
constexpr std::chrono::year_month &
    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)

Example

Run this code
#include <cassert>
#include <chrono>
 
int main()
{
    auto ym{std::chrono::day(1)/7/2023};
 
    ym -= std::chrono::years{2};
    assert(ym.month() == std::chrono::July);
    assert(ym.year() == std::chrono::year(2021));
 
    ym += std::chrono::months{7};
    assert(ym.month() == std::chrono::month(2));
    assert(ym.year() == std::chrono::year(2022));
}

See also

(C++20)
 performs arithmetic on year_month
(function)
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