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

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chrono I/O
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C-style date and time
std::chrono::month
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

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