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Calculate date from week number
Given Year, Month,Day and the Week number, is it possible to get the Date?
e.g. Year = 2010
Month =Jan
Day = Sun
WeekNumber = 3
output : 2010-01-10
I am trying it in c#
Thanks
I would make it like this:
int Year = 2010;
int Month = 1; //Jan=1, Feb=2, ...
int Day = 0; //Sun=0, Mon=1, ...
int WeekNumber = 3; // greater than 0
DateTime dateValue = new DateTime(Year, Month, 1);
int firstDay = (int)dateValue.DayOfWeek;
dateValue = dateValue.AddDays(Day - firstDay + (WeekNumber - 1) * 7);
I don't think there's something for such date calculations in plain .NET BCL. But there are libraries that can help you, see i.e. Fluent DateTime. Using this library, you can try something like that:
var firstWeekInYearBeginning = new DateTime(2010, 1, 2).Previous(DayOfWeek.Monday); // note 2 to not miss a week if the year begins on Monday
var expectedDate = 3.Weeks().From(firstWeekInYearBeginning);
Based on the APIs here, don't this its possible to initialize a DateTime Object from the information given. You would need to develop an algorithm to get the exact date of the year. A simple strategy would be to get the first Day of the month and based on that, find first Monday of the month. This is the start of WeekNumber 1 for that month, and you can locate your required Week by simpl loop and locate the exact date. You would then know the calendar date you are interested in.
BTW: I am assuming WeekNumber of a year/month starts from the first Monday of that Year/Month. Someone please correct me if I am wrong.
Maybe you should check out System.Globalization.Calendar class. It might be useful.
Related
What is the best way to calculate the numbered day of the week over an 8 week period?
For example, my app tracks a users progress over an 8 week course.
I'm stuck on how to determine the current numbered day of the week according to the weeks progress, for example, Week 6 - Day 5
I have the users course start date as DateTime from Firebase, and can obviously get DateTime.now() to calculate the difference between course start date and now. How do I go from this so that I can display for example:
Week 2 - Day 3 or Week 6 - Day 4
Let's say the course is started 15 days ago, you can get what you want by something like this:
DateTime now = DateTime.now();
DateTime start = now.subtract(Duration(days:15));
int allDays = now.difference(start).inDays;
int w = allDays ~/ 7 + 1;
int d = allDays % 7;
print('Week $w - day $d');
~/ is the Truncating Division Operator which gives you the Integer result of a division
This question already has answers here:
Converting a String to DateTime
(17 answers)
Closed 4 years ago.
I create a game in unity. And I add a 'buy subscribe' (apple).
After click buy, I get Date (for example: 08/02/2018 07:24:23) 08 - is month, 02 - is date.
I get a date through this code:
productReceipt.subscriptionExpirationDate
Now i need to do a check, if CurrentDay - 08/02/2018 07:24:23 = 15 days;
How to calculate 2 dates?
You can do it using DateTime function. DateTime function allows you to calculate the number of days. You just need to get current datetime & parse your string to datetime format. Here is the code.
DateTime dateCurrent = DateTime.Now;
DateTime dateNext = DateTime.Parse(date);
int days = (dateNext - dateCurrent).Days;
Update:
You can also use TotalDays function to give the remaining time in fraction also. TotalDays is double so remember to change the days to double when using it.
I am building a calendar application that needs to calculate the remaining days of (1) the current week and (2) the current month.
What I have tried was using the java.util.Calendar API, but it seems not to be fully supported.
int days = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
How would I do this in CN1?
Many thanks in advance.
We would love to add support for JSR310 in the future which would probably solve this in a more elegant way. This is something that can be done as a cn1lib without modifying Codename One but would require some work...
A bit of a hack to do this is:
int month = cal.get(Calendar.MONTH);
cal.set(Calendar.DAY_OF_MONTH, 1);
if(month == cal.DECEMBER) {
cal.set(Calendar.YEAR, cal.get(Calendar.YEAR) + 1);
cal.set(Calendar.MONTH, Calendar.JANUARY);
} else {
cal.set(Calendar.MONTH, month + 1);
}
int day = 24 * 60 * 60000;
cal.setTime(new Date(cal.getTime().getTime() - day));
I don't know CN1, but you can calculate the values using a subtraction between the max and the current value:
(1) cal.getActualMaximum(Calendar.DAY_OF_WEEK) - cal.get(Calendar.DAY_OF_WEEK)
(2) cal.getActualMaximum(Calendar.DAY_OF_MONTH) - cal.get(Calendar.DAY_OF_MONTH)
For your notification: The first day of the week is sunday in the api of calendar. When your week should start with monday you have to reduce the offset by 1.
We can use fbusdate to get the first business day of a month:
Date = fbusdate(Year, Month);
However, how do we get the first business day of a week?
As an example, during the week that I'm posting this, Monday 09/07/2017 was a holiday in the US:
isbusday(736942) % = 0
How do I determine that the first business day for this week would be the next day 736943?
I'm not aware of a builtin function that returns the first working day of a week, but you can obtain it by requesting the next working day after Sunday:
busdate(736941); % 736941 = Sunday 09/03/2017
Your desired fbusdateweek function can be done in one line using just the function weekday to get the first Sunday of the week then busdate to get the next business day after that:
dn = 736942; % Date number for any day in a week
Date = busdate(dn-weekday(dn)+1);
Note: busdate uses the function holidays by default to get all holidays and special nontrading days for the New York Stock Exchange. If necessary, you can define an alternate set of holidays for busdate to use as follows:
holidayArray = ...; % Some set of date numbers, vectors, or datetimes
Date = busdate(dn-weekday(dn)+1, 1, holidayArray);
This way you can define a set of localized holidays.
Solved it. Here is a function that is based on the answer of #m7913d:
function Busday = fbusdateweek(date)
% Return the first business day after Sunday
% 'date' is a datenum input
dperiod = date-6:date;
sundays = weekday(dperiod)==1;
sunday = find(sundays==1,1,'first');
datesunday = dperiod(sunday);
% -->
Busday = busdate(datesunday);
end
NOTE: I am a new Swift programmer, a NOOB if you will.
I am creating a school timetable app just for personal use to practise my coding. However, our school operates on a two week time table system, with 10 days, labeled 1 through to ten. I am wondering if anyone had some ideas as to how I could work out whether the current date is day one or day nine or day 4. I know I could use if statements for the dates, but the would take a long time, and require manual input of the dates. How could I have the app keep count of what day it is, skipping weekends?
EDIT - I could maybe have 14 days, with days 6,7,13 and 14 empty.
FOR EXAMPLE:
The current date is OCT 4, this is day one. I would like the app to be able to work out what day of the timetable the current date is. This would then load the appropriate day (e.g. Subject, Teacher, Classroom). Day One is Monday, Two is Tuesday, Five is Friday, Six is Monday, 10 is Friday. Could I have some sort of rostering system?
I am sorry if the question is vague, please tell me if I need to clarify.
I have been working on a fix for weeks now, so I have decided to turn to help. Any guidance whatsoever would be much appreciated, as I am at a dead end!
Many thanks
The numbers that I'm plugging into this example probably don't match your requirements but consider this as a strategy. (In this case, using a 1-to-14 cycle. If you'd rather get 1-to-10 you can put in a subtraction and a different error to throw on the "bad" days.)
class CyclicDay {
enum CyclicDayError: ErrorType {
case InvalidStartDate
}
lazy var baseline: NSDate? = {
// Set up some start date that matches day 1
var components = NSDateComponents()
components.day = 6
components.month = 9
components.year = 2015
return NSCalendar.currentCalendar().dateFromComponents(components)
}()
func dayOfCycle(testDate: NSDate) throws -> Int {
if let start = baseline {
// Convert difference to days
let interval = testDate.timeIntervalSinceDate(start)
let days = interval / (60 * 60 * 24)
// Convert to value 1..14 to position in a 2-week cycle
return Int(days % 14) + 1
}
throw CyclicDayError.InvalidStartDate
}
}
// Test today
let cd = CyclicDay()
let day = try cd.dayOfCycle(NSDate())