https://learn.microsoft.com/en-us/dotnet/api/system.globalization.persiancalendar.getdayofmonth?view=netframework-4.7.2
PersianCalendar.GetDayOfMonth(DateTime) Method (System.Globalization) | Microsoft Learn
Returns the day of the month in the specified DateTime object.
datetimemethodsystemglobalizationmicrosoft
https://learn.microsoft.com/en-gb/dotnet/api/system.globalization.calendar.getdayofmonth?view=netframework-4.8.1&viewFallbackFrom=net-9.0
Calendar.GetDayOfMonth(DateTime) Method (System.Globalization) | Microsoft Learn
When overridden in a derived class, returns the day of the month in the specified DateTime.
calendardatetimemethodsystemglobalization