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

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< cpp‎ | chrono‎ | year month

 
 
Utilities library
General utilities
Date and time
Function objects
Formatting library (C++20)
(C++11)
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)(C++20)(C++20)   
(C++20)
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(C++17)
(C++17)
(C++11)
(C++17)
(C++23)
Elementary string conversions
(C++17)
(C++17)
 
 
 
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) are preferred if the call would otherwise be ambiguous.

Example

#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

performs arithmetic on year_month
(function)