std::chrono::day::operator++, std::chrono::day::operator--
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                    |   constexpr std::chrono::day& operator++() noexcept;  | 
(1) | (since C++20) | 
|   constexpr std::chrono::day operator++(int) noexcept;  | 
(2) | (since C++20) | 
|   constexpr std::chrono::day& operator--() noexcept;  | 
(3) | (since C++20) | 
|   constexpr std::chrono::day operator--(int) noexcept;  | 
(4) | (since C++20) | 
Adds or subtracts 1 from the day value.
1-2) Performs *this += std::chrono::days{1};
3-4) Performs *this -= std::chrono::days{1};
Parameters
(none)
Return value
1,3) a reference to this 
day after modification2,4) a copy of the 
day made before modificationNotes
If the result would be outside the range [0, 255], the actual stored value is unspecified.
Example
| This section is incomplete Reason: no example  | 
See also
|    adds or subtracts a number of days   (public member function)  | |
   adds or subtracts a number of days and a day, or find the difference between two days  (function)  |