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

 

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C-style date and time

 

std::chrono::month

Member functions

month::month

month::operator++month::operator--

month::operator+=month::operator-=

month::operator unsigned

month::ok

Nonmember functions

operator==operator<=>

operator+operator-

operator<<

from_stream

Helper classes

formatter<std::chrono::month>

hash<std::chrono::month> (C++26)

 

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

Run this code

#include <cassert>
#include <chrono>
#include <iostream>
 
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

See also

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