Recently i was working with unit testing for my project.
I've given a task to test the method. The method should return the recent quarter date as per the current system date.
So, I've called the current system date using the following c# code:
string currentYear = DateTime.Now.ToString();
When i run the query it worked as expected.
So, its time for my tactics to raise a bug for that method. Hence I've changed the system date to 10/01/14 (dd/mm/yy).
Also I've customized current system date format to only keep last two digits of the year.
Ex: if year is 2014 the it shows only 14.
You can observe the short date and the long date in the following image.
When i run/debug the test in Visual Studio 2012, it still displays as 2014 as the current system date though I've modified it to 14.
Question: The real question is how did the system/program took the current year as 2014 even the system date is changed to 14. It may be silly but my doubt is Why it is not 1914 or 1814 and why it is 2014 ?.
Where did it store the current date or year information ? Does windows manage this stuff or did the C# taken care of the date ?
The real question is how did the system/program took the current year as 2014 even the system date is changed to 14. It may be silly but my doubt is Why it is not 1904 or 1804 and why it is 2014 ?.
C# only retrieved the date from the system, it was Windows that determined what data to send.
In the case of two-digit dates, Windows allows you to define what they mean in the Regional and Language applet in the Control Panel. This way you can specify the range you want it to represent depending on your usage.
The display of a date is not how it is stored, just how it is displayed.
January, 1st, 2014 may have a multitude of different formats, e.g.
2014-01-01
01-01-2014
01-01-14
1/1/14
Jan/1/14
001-2014
But all are held internally exactly the same way.
Note the advanced settings on your screenshot - this will indicate to many windows programs how to interpret a year entered as 2 digits, so it knows if it should regard a date entered as XX as 19XX or 20XX - this will cover manually entered dates, not the system date
Your C# application didn't store that date, Windows handled it for you.
As Sean mentioned, by changing from YYYY to YY you only changed how the date is displayed, not how it is stored. Windows doesn't store its system time information into a specific date format. Instead, it records the number of 100-milisecond intervals since 00:00 January 1st, 1601. That way it keeps the tracking of time independent of how it's displayed and allows you to display the date and time in a number of different formats.
As a curiosity, that specific date was chosen because the Gregorian calendar operates on a 400-year cycle (when it starts to repeat itself) and 1601 was the first year of the cycle that was active when Windows NT was being developed.
On a side note, Unix systems store that information as Unix Time or POSIX Time, counting the number of seconds elapsed since 00:00 January 1st 1970.
Related
Part of my program requires checking the day of the week that a file was created. I have an input attribute which gives the date of creation in US form (month/day/year). However I do not have the day of the week.
As per the sadism of the legal department I am also restricted to only the time modules within python's standard library so unfortunately the obvious solution of PYTZ is not an option.
My current approach is to use the date to reference the Gregorian calendar. On the assumption that a the same date is always the same day i.e. 1st September 2022 is a Thursday everywhere in the world. However, I have not been able to validate this assumption.
If you know if this assumption is correct/incorrect and/or know of somewhere I can find out I would be very grateful.
Thanks.
When configuring a Date attribute in Core Data, Xcode will show some default values in the Data Model inspector:
What is the significance of the timestamp there (1982-02-12 17:00:00), which might or might not be a local time (I'm using CET now, so that would be 16:00 UTC)? The Unix timestamp of these moments (382381200 and 382377600) don't ring a bell. Shifting them 31 years (Core Data usually counts from 2001-01-01) doesn't produce any insightful values either. Is it some kind of Easter Egg (perhaps one of the Xcode developers was born that day?)
I am working on my first application for mac which uses Core Data. Since I don't have much software development experience I would like to ask the more experienced developers the following question:
When entering data in some of the forms, user will have to enter a date in couple of the forms. Since app will be on app store and people from different continents will download it (I hope so) I am thinking of allowing the user to select his preferred date format from the preferences panel that I have in my app.
But I am wondering what will happen if after entering 500 or more records, he decide to change the date format again? Will that cause a mess in core data eventually?
Is this good idea or I should keep things simple and just get the system date (user computer date format) and use that date format? What would you do? Any advice will be deeply appreciated.
My advice is to keep date as timeinterval. You can see such method for NSDate.
The interval between the date object and 00:00:00 UTC on 1 January 1970.
So if you get NSDate object from NSDatFormatter object you will be able to obtain time in seconds since 1970. You could store this value in Core Data and use it later for creating NSDate objects. You will be able to use it for different locales and time zones as well as use the correct format.
'Dates' is complex topic and I suggest you to read guides about dates and date formatters.
First is to decide how you should store the date. The answer here is as an NSDate. The NSDate is a single unique precise point in time, thus it in a sense stores both date and time.
This means that for example 1 PM in Berlin and 8 pm in Kuala Lumpur will be the exact same NSDate value (during winter months) but 2 pm in London and 2 pm in Paris the same calendar date will not be the same NSDate value. This is a quite complex topic, read the date and time programming topics documentation from Apple.
Then as you say you need to allow you user to input the date. The way to do that is to use a NSDateFormatter tied to your input control. The formatter can be defined to be as per system settings, which means you will get the localisation you are seeking for free, so that is in fact easy.
The tricky thing you are really facing is to determine what you are really looking to store if it is only the calendar date without an associated time you want to store. For example you decide store the date combined with 12.00 noon in the local timezone. Then if the user shifts to another timezone more than 12 hours away the date may be displayed as the previous date or the next. The safest bet is to store the date combined with 12:00 noon GMT as this is in the middle of the time zone range. There are a few locations 13 and 14 hours off that could exhibit the mentioned problem anyway, but these are small atolls in the pacific and could possibly be safely ignored.
However the the best thing is if you can in fact determine that what you are looking to store is really a precise point in time rather than a date (which is a 24 hour fuzzy definition). For example in a calendar app an event usually takes place at a specific time on a specific date, then store that time and date.
I'm writing an app that relies on the calendar and calendar events to display data to the user.
I need to be able to let the user select the beginning of his/her 'fiscal' year in settings, which will be the 1st of any of the 12 months. This is an app for military users, and any given unit's fiscal year can begin on whatever month their unit (base) decides.
The data I'm displaying to the user needs to be divided into 'fiscal' quarters according to the user's setting of the beginning of the fiscal year, not calendar year.
I'm not having problems retrieving, editing or deleting the events, I can't figure out how to change the beginning of the year to anything besides Jan 1st.
I found NSDateCategoryForReporting on GitHub, that seems like it's exactly what I need, but how do I tell it that the year begins on the 1st of x month?
iOS doesn't natively support this, so you'll have to find a plugin to do this or write your own. Your best bet is to write a class that performs the date conversions using the standard NSDate, NSCalendar, etc.
For instance, you could store what day the user specifies as their starting fiscal year. Then you can calculate the number of days difference between that and January 1st, and just shift dates based on that.
I'm in the process of migrating our Data Warehouse from Oracle to SQL Server 2012.
One piece of code I use a hundred times a day in Oracle is changing the date format for a query by using something like:
To_Char(entry_date,'WMMYY') = 30612
The above allows me to grab the date (default format = DD-MON-YY eg 01-JAN-12) and change the format for the week specified (the third week of June in the above example) by simply listing the week desired.
In my mind the above is very simple and easy to use. I can change it to whatever format I want (MMYY, MMYYYY) etc. without any issues. So far I cannot figure out an easy way to do this in SQL Server 2012 and it's really starting to bother me. It's datetime2 in SQL Server.
I'm finding stuff for CAST(), CONVERT(), DATEPART() but from what I've seen there is all kinds of wacky coding and number codes (like 101, 102, I don't understand why this is) required which just seems extraneous and over complicated to me.
Have I just not found what I'm looking for yet or is this just the way it is with SQL Server? I just want to be able to do something simple like grab all the data that was entered in during the month of june or the second week of october without having to add 200 extra characters of code.
It's a switch. You are using SQL Server 2012, so look into FORMAT() function. http://technet.microsoft.com/en-us/library/hh213505%28SQL.110%29.aspx I'm not, so unfortunately I can't test anything out for you - but there are some date formatting improvements.
For those of us who aren't - , there are things you can do that will be great - once you get used to them. This isn't specific to SQL Server - but Week of Month varies from organization to organization - so you'd have to define that to get a good example for 3rd week of month, etc. Also, when using DATEPART with week or day arguments, what gets returned is determined by the setting for the first day of the week (1 -7 - ##DATEFIRST). The numeric styles for CONVERT (again check out FORMAT() if you're on 2012) are definitely not as intuitive - but you'll probably be using the same styles over and over, and you'll have them memorized quickly. If you are set on 'WMMYY' or just use something over and over that doesn't have a satisfactory built in solution- create a UDF.
data that was entered in during the month of june
DATEPART(mm,#date) = 6
current month
month(getDate())
Or this week
DATEPART(ww,GetDate())