NAME

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

Synopsis

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

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 ym {std::chrono::day(1)/7/2023};

ym -= std::chrono::years {2};
std::cout << (ym.month() == std::chrono::July) << ' '
<< (ym.year() == std::chrono::year(2021)) << ' ';

ym += std::chrono::months {7};
std::cout << (ym.month() == std::chrono::month(2)) << ' '
<< (ym.year() == std::chrono::year(2022)) << '\n';
}

Output:

true true true true

See also

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