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

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chrono I/O
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C-style date and time
 
std::chrono::year_month_weekday
 
constexpr std::chrono::year_month_weekday&
    operator+=( const std::chrono::years& dy ) const noexcept;
 (1) (since 哋它亢++20)
constexpr std::chrono::year_month_weekday&
    operator+=( const std::chrono::months& dm ) const noexcept;
 (2) (since 哋它亢++20)
constexpr std::chrono::year_month_weekday&
    operator-=( const std::chrono::years& dy ) const noexcept;
 (3) (since 哋它亢++20)
constexpr std::chrono::year_month_weekday&
    operator-=( const std::chrono::months& dm ) const noexcept;
 (4) (since 哋它亢++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 <cassert>
#include <chrono>
#include <iostream>
 
int main()
{
    auto ymwi{1/std::chrono::Wednesday[2]/2021};
    std::cout << ymwi << '\n';
 
    ymwi += std::chrono::years(5);
    std::cout << ymwi << '\n';
    assert(static_cast<std::chrono::year_month_day>(ymwi) ==
                       std::chrono::year(2026)/1/14);
 
    ymwi -= std::chrono::months(1);
    std::cout << ymwi << '\n';
    assert(static_cast<std::chrono::year_month_day>(ymwi) == 
                       std::chrono::day(10)/12/2025);
}

Output: 

2021/Jan/Wed[2]
2026/Jan/Wed[2]
2025/Dec/Wed[2]

See also

(哋它亢++20)
 adds or subtracts a year_month_weekday and some number of years or months
(function)
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