What if I told you that weekend days are locale dependent?!

Time and date is the black hole where optimistic programmers go to die. Nothing is simply with localisation and if you think it is, you mustn’t have worked enough with it.

Source: Run a system that schedules millions of interactions across the world and deeply depend on this. The amount of code to manage and/or call out to external services to give us information about time zones, summer time, locale specific settings, day names, calendar systems, week numbers etc etc.

Here's a fun thought experiment: What gregorian year and date will the spacian date value of zero correlate to? Trick question.

The atomic clock on the moon and every other celestial body colonized will simply start at zero, and thanks to relativity it will not actually be the same rate of time passing as on earth.

Enjoy your nightmares.

Luckily we won't colonize the moon or another planet anytime soon...

IMO every datetime should be in utc, and variables for datetimes should either be suffixed "Utc" or have a type indicating their time zone (DateTimeOffset or UtcDateTime etc). Conversion to local time happens at the last possible second (e.g. in the view model or an outbound http request parameter). Of course that doesn't solve the problem of interoperating with other ~~morons~~ programmers who don't follow these rules, but it keeps things a lot neater locally.

Scheduling based on regional time conventions (holidays, weekends, etc) is just not great though.

2 timezones but the complication is that it is dependent on which country you're in?

The obvious solution is to inject an IWeekendDaysOfWeekProvider service in the inversion of control container. In your, uh, javascript web app.

Not using CultureInfo.InvariantCulture for basically everything

This dude(ette) globalizes.

I was wondering why the second example returned monday and tuesday. I had no idea the week could start any day other than monday

But if you're worried about locale, you can't assume people use the string "Saturday" to describe Saturday either. That solution only works in English.

Yeah it's the front end of the week and Saturday is the rear end

They're the week's ends, front and back.

A rope has two ends, and so does a week

If you're referring to an "end" of an object, it can refer to the extreme of a side of it. For example, aglets are at either end of a shoelace.

Until some idiot sends in "Sunday" as days of the week...

Can confirm this works completely as expected when the user's system is set to lang=ES.

Zat is vhen ve party!