2012-12-31 in Powershell 7.1.1 still gives week 53 should be 1 When using: Calendar.GetWeekOfYear

2012-12-31 in Powershell 7.1.1 still gives week 53 should be 1 When using: (Get-Culture).Calendar.GetWeekOfYear('2012-12-31', (Get-Culture).DateTimeFormat.CalendarWeekRule, (Get-Culture).DateTimeFormat.FirstDayOfWeek) The formula should be based on the number of Thursdays in THIS year and must be starting with a Thursday or a Wendsday( When this is a Leapyear.) ‘2012-01-01’ is a Sunday…?

Probably the issue exist because Sunday = 0 instead of Monday.

http://week-number.net/calendar-with-week-numbers-2012.html

<div>2012 calendar with Week Numbers - What week is it?</div>

_Originally posted by @B-Art in https://github.com/PowerShell/PowerShell/issues/11534#issuecomment-772867962_

[daxian-dbw]

@B-Art You are calling a .NET API Calendar.GetWeekOfYear(DateTime, CalendarWeekRule, DayOfWeek). If you have question about the behavior of that API, please open an issue in https://github.com/dotnet/runtime or post a question in their Discussions.

<div> GitHub</div><div>dotnet/runtime</div><div>.NET is a cross-platform runtime for cloud, mobile, desktop, and IoT apps. - dotnet/runtime</div>

[KalleOlaviNiemitalo]

What is the UICulture, then? If it is U.S. English, then perhaps it is correct to use non-ISO week numbers there.