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std::chrono::month::operator++, std::chrono::month::operator--

constexpr std::chrono::month& operator++() noexcept;	(1)	(since C++20)
constexpr std::chrono::month operator++(int) noexcept;	(2)	(since C++20)
constexpr std::chrono::month& operator--() noexcept;	(3)	(since C++20)
constexpr std::chrono::month operator--(int) noexcept;	(4)	(since C++20)

Adds or subtracts 1 from the month value, reducing the result modulo 12 to an integer in the range [1, 12].

1-2) Performs *this += std::chrono::months{1};

3-4) Performs *this -= std::chrono::months{1};

Parameters

(none).

Return value

1,3) a reference to this month after modification

2,4) a copy of the month made before modification

Notes

After a call to one of these functions, ok() is always true.

Example

#include <cassert>
#include <iostream>
#include <chrono>
 
int main()
{
    std::chrono::month m {6};
 
    ++m;
    assert(m == std::chrono::month(7));
 
    --m;
    assert(m == std::chrono::month(6));
 
    m = std::chrono::December;
    m++; // rounds up to January
    assert(m.ok());
    std::cout << unsigned(m) << '\n';
 
    m = std::chrono::January;
    m--; // rounds down to December
    assert(m.ok());
    std::cout << unsigned(m) << '\n';
}

Output:

1
12

operator+=operator-=	adds or subtracts a number of months (public member function)
operator+operator- (C++20)	performs arithmetic on `month`s (function)

std::chrono::month::operator++, std::chrono::month::operator--

Parameters

Return value

Notes

Example

See also