NAME¶

std::chrono::operator+,std::chrono::operator-(std::chrono::day) - std::chrono::operator+,std::chrono::operator-(std::chrono::day)

Synopsis¶

Defined in header <chrono>
constexpr std::chrono::day operator+( const std::chrono::day& d, (1) (since C++20)
const std::chrono::days& ds ) noexcept;
constexpr std::chrono::day operator+( const std::chrono::days& ds, (2) (since C++20)
const std::chrono::day& d ) noexcept;
constexpr std::chrono::day operator-( const std::chrono::day& d, (3) (since C++20)
const std::chrono::days& ds ) noexcept;
constexpr std::chrono::days operator-( const std::chrono::day& x, (4) (since C++20)
const std::chrono::day& y ) noexcept;

1-2) Adds ds.count() days to d.
3) Subtracts ds.count() days from d.
4) Calculate the difference, in days, between two day x and y.

Return value¶

1-2) std::chrono::day(unsigned(d) + ds.count())
3) std::chrono::day(unsigned(d) - ds.count())
4) std::chrono::days(int(unsigned(x)) - int(unsigned(y)))

Notes¶

For (1-3), if the result would be outside the range [0, 255], the actual stored
value is unspecified.

Example¶

// Run this code

#include <chrono>
#include <cassert>

int main()
{
std::chrono::day d {15};

d = d + std::chrono::days(2);
assert(d == std::chrono::day(17));

d = d - std::chrono::days(3);
assert(d == std::chrono::day(14));

constexpr std::chrono::days ds = std::chrono::day(16) - std::chrono::day(14);
static_assert(ds == std::chrono::days(2));
}

See also¶

operator++
operator++(int) increments or decrements the day
operator-- (public member function)
operator--(int)
operator+= adds or subtracts a number of days
operator-= (public member function)