Timezone VS date

There are Arduino libraries that do exactly what you want. TimeLib (https://github.com/PaulStoffregen/Time) supports all the time functions, and Timezone (https://github.com/JChristensen/Timezone) supports conversions between UTC and local time.

> but I'd be surprised if there was not a modern date library for C++

The standard library now includes . AFAIK: It was mostly written by Howard Hinnant. He now has more date/time libs that expand upon : https://github.com/HowardHinnant/date

Ah: https://github.com/HowardHinnant/date/issues/178 https://stackoverflow.com/questions/62734974/how-do-i-add-a-number-of-days-to-a-date-in-c20-chrono

If you’re using an earlier standard you can use this, which the ‘official’ date/time zone stuff was based on: https://github.com/HowardHinnant/date

If you don't have C++20, or if your vendor hasn't shipped it yet, here is a free, open-source, header-only preview of this part of C++20 that you can use: https://github.com/HowardHinnant/date

C++20 adds the timezone/caldendaring/formatting from Howard Hinnat’s Date Library https://github.com/howardhinnant/date .

So calendrical calculations and time zone support.

Unfortunately only implemented in MSVC right now, for other compilers and/or if you want to do anything with dates I suggest you use https://github.com/HowardHinnant/date directly, chrono is good enough for measuring time but if you do more complex things it can get a bit wild.

Here is the original calendar library that was adopted in C++20 (corrected link).

In lower C++ standards I would highly recommend including this as a header-only library: https://github.com/HowardHinnant/date. This was the basis for the new date/timezone functionality in C++20, so it's nearly identical and works down to C++11.

So you want date time functionality? Those come with c++20 otherwise you can use this. The author Howard Hinnant is the author of c++ chrono had have a few excellent video on YouTube explaining how to use chrono.