std::chrono...chrono::day)(3)

✨ NAME ✨

Hey bestie 💖 welcome to the std::chrono...chrono::day)(3) page from the C++ Standard Libary manual — yes, that’s the manual name, spelling preserved, ily. This whole page is about std::chrono::operator+,std::chrono::operator-(std::chrono::day): the add/subtract ops for std::chrono::day. Literally day-math main character energy. 👑

🌸 Synopsis 🌸

Defined in header <chrono> ✨

(1) (since C++20)

constexpr std::chrono::day operator+( const std::chrono::day&  d,
                                      const std::chrono::days& ds ) noexcept;

(2) (since C++20)

constexpr std::chrono::day operator+( const std::chrono::days& ds,
                                      const std::chrono::day&  d ) noexcept;

(3) (since C++20)

constexpr std::chrono::day operator-( const std::chrono::day&  d,
                                      const std::chrono::days& ds ) noexcept;

(4) (since C++20)

constexpr std::chrono::days operator-( const std::chrono::day& x,
                                       const std::chrono::day& y ) noexcept;

What they do, bestie:

• 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. ⚠️ Not “unspecified but cute.” It’s literally unspecified, so don’t act like it’s guaranteed, fr fr.

🍓 Example 🍓

// Run this code — yes, literally the manpage’s little run label. Then:

#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), operator+=, operator-= — these are public member functions; operator++ / operator-- increment or decrement the day, and operator+= / operator-= add or subtract a number of days. The whole member-function squad ate, no cap. 💅

okay that’s the whole page, mwah 🫶🌈 — source: http://cppreference.com · date: 2024.06.10. Bye bestie, go do iconic calendar math. 👑💜