std::chrono::month::operator+=, std::chrono::month::operator-=
From cppreference.com
constexpr std::chrono::month& operator+=( const std::chrono::months& m ) noexcept; |
(1) | (since C++20) |
constexpr std::chrono::month& operator-=( const std::chrono::months& m ) noexcept; |
(2) | (since C++20) |
Adds or subtracts m.count() from the month value, reducing the result modulo 12 to an integer in the range [
1,
12]
.
1) Performs *this = *this + m;.
2) Performs *this = *this - m;.
Contents |
[edit] Return value
A reference to this month
after modification.
[edit] Notes
After a call to one of these functions, ok()
is always true if no overflow occurred during the operation.
[edit] Example
Run this code
#include <chrono> #include <iostream> int main() { std::cout << std::boolalpha; std::chrono::month m{6}; m += std::chrono::months(2); std::cout << (m == std::chrono::month(8)) << ' ' << (m == std::chrono::August) << ' '; m -= std::chrono::months(3); std::cout << (m == std::chrono::month(5)) << ' ' << (m == std::chrono::May) << ' '; m = std::chrono::October; m += std::chrono::months{8}; // ((10 += 8 == 18) % 12) == 6; std::cout << (m == std::chrono::June) << ' '; m -= std::chrono::months{std::chrono::December - std::chrono::February}; // -= 10 // (6 -= 10) == -4; -4 % 12 == (12 - 4) == 8 std::cout << (m == std::chrono::August) << '\n'; }
Output:
true true true true true true
[edit] See also
increments or decrements the month (public member function) | |
(C++20) |
performs arithmetic on month s (function) |