What is expected datetime string for ar-sa culture

问题:

I have a method

DateToString(DateTime datetime, string format, CultureInfo cultrueInfo)
{
    return datetime.ToString(format, cultureInfo);
}

Parameters:

datetime: {10/1/2016 12:00:00 AM}
format: "ddd, dd MMM"
cultureInfo: {ar-SA}

But it returns me "السبت, 30 ذو الحجة". October 1st is Saturday. Why it seems return me September 30, Saturday? Anything wrong at my side?

回答1:

ar-SA culture uses UmAlQuraCalendar a calendar.

new CultureInfo("ar-SA").Calendar.Dump(); // System.Globalization.UmAlQuraCalendar

Since you used that culture in your ToString method, it will generated a string representation based on that calendar. You can't expect to generate "September" since your culture does not use GregorianCalendar.

In UmAlQuraCalendar, your DateTiem will be represented as 30-12-1437.

var dt = new DateTime(2016, 10, 1);  // Gregorian

var umAlQura = new UmAlQuraCalendar();

umAlQura.GetYear(dt);       // 1437
umAlQura.GetMonth(dt);      // 12
umAlQura.GetDayOfMonth(dt); // 30

https://www.staff.science.uu.nl/~gent0113/islam/ummalqura_converter.htm

That's why:

• ddd format specifier generates السبت ((Yawm) as-Sabt aka Saturday) since it is the abbreviated day name.
• dd format specifier generates 30 as expected.
• MMM format specifier generates ذو الحجة (Dhu al-Hijjah) since it is the abbreviated month name.

As you can see, abbreviated day and month name switched in result. This is probably a Right to left issue.