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

 

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chrono I/O
parse (C++20)
C-style date and time

 

std::chrono::day

Member functions

day::day

day::operator++day::operator--

day::operator+=day::operator-=

day::operator unsigned

day::ok

Nonmember functions

operator==operator<=>

operator+operator-

operator<<

from_stream

operator""d

Helper classes

formatter<std::chrono::day>

hash<std::chrono::day> (C++26)

 

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

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

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

Example

Run this code

#include <cassert>
#include <chrono>
 
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)operator--operator--(int)	increments or decrements the day (public member function)
operator+=operator-=	adds or subtracts a number of days (public member function)