How to determine upcoming months relative to a given month in any calendar?

Question

How can I find out the upcoming months relative to a given month according to the calendar that I select?

Meaning I selected the Gregorian calendar and the given month is September, a list of the following months will appear:

[September, October, November, December]

If the Hijri calendar is selected and the current month is: Dhu al-Qa’dah, a list of the remaining months will appear, which are:

[Dhul Qi'dah, Dhul Hijjah]

I used the following reference to make the code but it didn't work

System.Globalization.CultureInfo(DateLangCulture, false).DateTimeFormat

Maybe: https://stackoverflow.com/q/11189807/14171304 – dr.null Dec 27 '21 at 00:13 — dr.null, Dec 27 '21 at 00:13

score 1 · Accepted Answer · answered Dec 26 '21 at 20:35

In .NET Framework, month names are based on a culture. If I understand your question clearly, you wanna select some "Calendar" and wanna list some months of it. I think there is a problem with this approach because different cultures might use the same calendar and these different cultures might have different month names.

For example, let's take GregorianCalendar, if you wanna list english-based month names, you can clearly use a culture like InvariantCulture which you will get January, February, March etc.. But on the other side, Turkish culture (tr-TR) also uses GregorianCalendar as a calendar but it's month names are like Ocak, Şubat, Mart etc. That means, even if you choose a "right" CultureInfo for your calendar, you might have a language problem as well. I hope you understand my concern. A calendar months might have a different languages since they are belongs on cultures.

If you really wanna get these based on calendars, you can create a CultureInfo which uses selected Calendar and list their MonthNames property as a string array which starts with the current month.

For example; for GregorianCalendar, you can use InvariantCulture which month names are;

CultureInfo.InvariantCulture.DateTimeFormat.MonthNames

January February March April May June July August September October November December

and for HijriCalendar, you can use ar-SA culture (it uses UmAlQuraCalendar which is close enough to HijriCalendar in my opinion) which month names are;

(new CultureInfo("ar-SA")).DateTimeFormat.MonthNames

محرم صفر ربيع الأول ربيع الآخر جمادى الأولى جمادى الآخرة رجب شعبان رمضان شوال ذو القعدة ذو الحجة

which they can be translated to English as;

You can get the current month number as;

var currentMonthNo = Datetime.Now.Month;

then you can start to iterate from it's previous index (since array start index 0) to the end of the array (Be aware, there are some calendars that have 13 months, that's why for 12 month cultures the 13th element of the array is an empty string.)

Suppose the client machine has a Hijri calendar, and I just want to use only the Gregorian calendar, and I want to extract the names of the months with the month number in a dropdown only — ebrahem b, Dec 26 '21 at 23:20
@ebrahemb Then you have to check first which calendar that client uses and after it, create a `CultureInfo` that corresponds with _that_ calendar and iterate the `MonthNames` propert starting with the current month number which always you can get using `Datetime.Now.Month` for gregorian calendar. Have you ever tried to code it? Sounds like you only asking for theoretical implementation instead of _actually_ implement it. — Soner Gönül, Dec 27 '21 at 13:23

score 0 · Answer 2 · answered Dec 27 '21 at 09:42

Only supplement Soner Gönül's answer.

If you want to get the Gregorian calendar month according to the current system calendar, you can refer to the following code:

namespace ConsoleApp1 {
    internal class Program {
        static void Main (string[] args) {
            //CultureInfo culture = CultureInfo.GetCultureInfo("en-US");
            //CultureInfo culture = CultureInfo.GetCultureInfo("ar-SA");
            CultureInfo culture = CultureInfo.GetCultureInfo("fr");
            List<KeyValuePair<int,string>> months = new List<KeyValuePair<int,string>>();
            for (int i = getCurMonth(); i <= 12; i++)
                {
                months.Add(new KeyValuePair<int, string>(i, DateTime.Parse(DateTime.Now.Year.ToString() + "-" + i + "-1").ToString("MMMM", culture)));
                }
            foreach (KeyValuePair<int, string> month in months)
                {
                Console.WriteLine(month.Value);
                }
            Console.ReadLine();
            }
        static int getCurMonth () {
            return DateTime.Now.Month;
            }
        }
    }

To obtain a specific country calendar, the system must install the corresponding character set.

You can see the following example:

en-us

CultureInfo culture = CultureInfo.GetCultureInfo("en-US");

Output:

fr

CultureInfo culture = CultureInfo.GetCultureInfo("fr")