c# - Hijri and Gregorian DateTime constructor

Question

what is the correct behavior for the Calendar objected passed to the constructor of DateTime type?

I have the components year, month and day as the below example:

day = 1
month = 5 
year = 1433 (which is the current Hijri year)

when creating a datetime object using the below code the result is a valid Greg Date

HijriCalendar hijri = new HijriCalendar();
//Get the First Day in the Month
DateTime firstDayInMonth = new DateTime(1433, month, 1, hijri);

while using the below code generates a valid Hijri date:

GregorianCalendar greg = new GregorianCalendar();
//Get the First Day in the Month
DateTime firstDayInMonth = new DateTime(1433, month, 1, greg);

is that a correct result?

Answer 1

Your first example is correct. The DateTime will not be in the Hijri format, it will just be the standardised equivalent of what you gave it. See the following code for how to get the Hirji date:

HijriCalendar hijri = new HijriCalendar();
DateTime firstDayInMonth = new DateTime(1433, 10, 11, hijri);
Console.WriteLine(hijri.GetEra(firstDayInMonth)); // 1
Console.WriteLine(hijri.GetYear(firstDayInMonth)); // 1433
Console.WriteLine(hijri.GetMonth(firstDayInMonth)); // 10
Console.WriteLine(hijri.GetDayOfMonth(firstDayInMonth)); // 11

Your second block of code was just setting the gregorian date "1/1/1433" so when you were inspecting it you weren't getting a hirji date, you were just getting the date you gave it in the 15th century.

Looking at http://msdn.microsoft.com/en-us/library/system.globalization.hijricalendar.aspx and seeing the methods there should give you a better idea of what you should be doing on the calendar object and what should happen on the DateTime object.