std::chrono::weekday::operator++,std::chrono::weekday::operator--(3)

NAME
std::chrono::weekday::operator++,std::chrono::weekday::operator-- - std::chrono::weekday::operator++,std::chrono::weekday::operator--

Synopsis
   constexpr std::chrono::weekday& operator++() noexcept; (1) (since C++20)
   constexpr std::chrono::weekday operator++( int ) noexcept; (2) (since C++20)
   constexpr std::chrono::weekday& operator--() noexcept; (3) (since C++20)
   constexpr std::chrono::weekday operator--( int ) noexcept; (4) (since C++20)
   Adds or subtracts 1 from the weekday value, reducing the result modulo 7 to an
   integer in the range [0, 6].
   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 weekday after modification.
   2,4) A copy of the weekday 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::cout << std::boolalpha;
     std::chrono::weekday wd{0}; // Sunday is 0 or 7
     --wd;
     std::cout << (wd == std::chrono::Saturday) << ' ';
     ++wd;
     std::cout << (wd == std::chrono::Sunday) << '\n';
     wd = std::chrono::weekday{13};
     assert(!wd.ok());
     wd++;
     assert(wd.ok());
 }

Output:
 true true

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