std::chrono::operator+, std::chrono::operator- (std::chrono::weekday)
From cppreference.com
Defined in header <chrono>
|
||
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constexpr
std::chrono::weekday operator+
(
const
std::chrono::weekday
& wd,
const std::chrono::days & d ) noexcept ; |
(1) | (since C++20) |
|
constexpr
std::chrono::weekday operator+
(
const
std::chrono::days
& d,
const std::chrono::weekday & wd ) noexcept ; |
(2) | (since C++20) |
|
constexpr
std::chrono::weekday operator-
(
const
std::chrono::weekday
& wd,
const std::chrono::days & d ) noexcept ; |
(3) | (since C++20) |
|
constexpr
std::chrono::days operator-
(
const
std::chrono::weekday
& wd1,
const std::chrono::weekday & wd2 ) noexcept ; |
(4) | (since C++20) |
1,2) Adds d.count() days to wd. The weekday value held in the result is computed by first evaluating
static_cast
<
long
long
>
(wd.c_encoding
(
)
)
+ d.count
(
)
and reducing it modulo 7 to an integer in the range
[
0
,
6
]
3) Subtracts d.count() days from wd. Equivalent to return wd + -d;
4) If wd1.ok() and wd2.ok() are both true, returns a std::chrono::days value d such that d.count() is in the range
[
0
,
6
]
and wd2 + d == wd1
Return value
1-3) A std::chrono::weekday holding a weekday value calculated as described above.
4) A std::chrono::days representing the distance between wd1 and wd2
Notes
As long as the computation doesn't overflow, (1-3) always return a valid weekday even if wd.ok() is false
Example
Run this code
#include <chrono> #include <iostream> int main() { std::cout << std::boolalpha; std::chrono::weekday wd{4}; wd = wd + std::chrono::days(2); std::cout << (wd == std::chrono::weekday(6)) << ' ' << (wd == std::chrono::Saturday) << ' '; wd = wd - std::chrono::days(3); std::cout << (wd == std::chrono::weekday(3)) << ' ' << (wd == std::chrono::Wednesday) << ' '; wd = std::chrono::Tuesday; wd = wd + std::chrono::days{8}; // (((2 + 8) == 10) % 7) == 3; std::cout << (wd == std::chrono::Wednesday) << ' '; wd = wd + (std::chrono::Sunday - std::chrono::Thursday); // (3 + 3) == 6 std::cout << (wd == std::chrono::Saturday) << '\n'; }
Output:
true true true true true true
See also
| increments or decrements the weekday (public member function) |
|
| adds or subtracts a number of days (public member function) |