I need to parse dates in my program, but it fails on the machine of one user (in denmark). It works for his colleagues who all has the same settings as far as I can tell.
The code looks as follows:
DateTime result;
if (DateTime.TryParse(InputBox.Text, out result))
YyyymmddField.Text = result.ToString("yyyyMMdd");
else
YyyymmddField.Text = "(invalid)";
CurrentCulture is da-DK and his configured format is: yyyy.MM.dd. The date string I want to parse is 2015.07.14.
This works on our machines here (in sweden) regardless of current culture. It also works for his colleagues, but not for him.
We have hundreds of users worldwide and as far as we know, his is the only computer that fails.
Could something other than the current CultureInfo affect how TryParse operates?
This works on our machines here (in sweden) regardless of current
culture
No. There is no such a thing. If you use DateTime.TryParse without any IFormatProvider, it will use the CurrentCulture settings of the current machine.
From documentation;
The string s is parsed using formatting information in the current
DateTimeFormatInfo object, which is supplied implicitly by the current
thread culture.
I'm using .NET Framework 4.5 and there are only 7 culture inside of AllCultures that doesn't have this as standard date and time format. If you won't/can't tell us what is your other colleague's CurrentCulture, I would assume he will use one of these from my perspective.
ar
bn
ml
ar-SA
bn-IN
ml-IN
bn-BD
Instead of that confusion, you can use InvariantCulture is your string has a stable format like yyyy.MM.dd instead of hoping his CurrentCulture settings will parse it or not.
use CultureInfo.InvariantCulture
DateTime result;
if (DateTime.TryParse(InputBox.Text, out result))
YyyymmddField.Text = result.ToString("yyyyMMdd",CultureInfo.InvariantCulture);
else
YyyymmddField.Text = "(invalid)";
In principle, it can be a good idea to have reusable methods (such as extension methods) for parsing DateTimes and numerics, which use the invariant culture.
Related
I am currently fixing FxCop issues so I encountered issue where I have to provide cultureinfo when converting a string using ToString() .
Currently in my code nothing we are passing as IFormatProvider so I have read some msdn articles saying that when you don't pass any value for cultureinfo it will assign a default value and when you specify CultureInfo as InvariantCulture it will be independent of any culture.
My question is, "Are default and CultureInfo.InvariantCulture one and the same? Can I replace all my code from default to InvariantCulture?"
Ex :
int st = 123;
String s = st.ToString(123); // this will be taken as default
String s = st.ToString(123, CultureInfo.InvariantCulture); // culture is specified externally
Are the second and third lines equivalent?
Is default and CultureInfo.InvariantCulture are one and the same?
No, absolutely not. The default culture depends (initially) on the operating system settings. The invariant culture is meant to be a "neutral" culture.
Your example of 123 isn't a great one, because most (all?) cultures will represent integers the same way - at least until you get into formats with grouping separators etc. (I don't think .NET supports non-Arabic numerals when formatting integers.)
Compare that with formatting a decimal value, for example:
decimal x = 123.45m;
Console.WriteLine(x.ToString()); // Might be 123,45
Console.WriteLine(x.ToString(CultureInfo.InvariantCulture)); // Always 123.45
If you run the above code in (say) France, the default culture will be French, which uses a comma as a decimal separator - so it will print out "123,45".
The rule of thumb to remember is that the invariant culture is suitable for machine-to-machine communications (e.g. formatting values in JSON or XML) whereas other cultures are more suitable for displaying information directly to users.
Although the default culture is originally based on the operating system settings, it can be changed using Thread.CurrentCulture and Thread.CurrentUICulture; the latter is used for looking up translated resources, whereas the former is used for formatting decisions like the above. You can set these properties on any thread, but typically you'd use Thread.CurrentThread.CurrentCulture = ...
No, they are not the same.
The first will take the regional settings from the computer or the culture settings from the application thread running.
The second one will take the English language, according to MSDN:
The invariant culture is culture-insensitive; it is associated with the English language but not with any country/region.
I have the following code:
DateTime.TryParse("06-28-2012", new System.Globalization.CultureInfo("en-NZ"),
System.Globalization.DateTimeStyles.AssumeLocal, out date);
I'm not sure why this is returning true since if I go into my Regional Settings in Windows, I only see the following date formats under short date:
d/MM/yyyy
d/MM/yy
dd/MM/yy
d.MM.yy
yyyy-MM-dd
So then why is a short date format like MM-dd-yyyy returning true? Shouldn't it return false?
I'm using this similar post as a source: DateTime c# parsing
Important:
Please note that I also have my regional settings set to use English (New Zealand) and chose
yyyy-MM-dd as my short date format.
Having your short date format set to yyyy-MM-dd is the cause of this behavior (I do not know if that the standard in New Zealand, but New Zealand's short date is set to d/MM/yyyy on my computer). I do not know if Dot Net, or the underlying Windows APIs are to blame, but it seems like it's smart enough to understand that the 4-digits part represents the year, and after that it just preserves the month-day order (Note that calling DateTime.TryParse("28-06-2012") will actually fail).
You can try using ParseExact, but be warned that will fail on a slightest change of the string (for example, when using a dot or a slash as a separator, instead of a dash.
In my opinion, it's probably best to leave the behavior as is, as it can handle more cases, but if you really must check if a date string was in a specified (yet flexible) format, Regex is the best option. For example Regex.IsMatch("2012/06/28", #"[0-9][0-9][0-9][0-9][./\\][0-9][0-9]?[./\\][0-9][0-9]?"); should suit your needs, while still allowing some flexibility.
You could try DateTime.ParseExact
Could you execute and post the result from the code below?
System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.ShortDatePattern;
System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat.DateSeparator;
I want to be able to check against the environments timezone settings and if its not a US timezone then I will handle the datetime with a more global format. For example. I have a user in America their settings is MM-DD-YYYY now if I have another user in Canada they want to see DD-MM-YYYY but instead of just giving them different versions I would rather have some logic that grabs the timezone and compares it against something and then that determines how the datetime will be handled.
if(System.TimeZone.StandardTime = US)
{
objOrderEntryItemUsageReport.VarShipDate = Convert.ToDateTime(datpkrShipDate.Value).ToString("MM/DD/YYYY");
}
else
{
objOrderEntryItemUsageReport.VarShipDate = Convert.ToDateTime(datpkrShipDate.Value).ToString("DD/MM/YYYY");
I just don't know the best way to check the environments timezone settings and even how to compare it to see if its a US timezone?
Would I need to create a dictionary with the American timezones in it and then do a while loop through that dictionary to see if the current timezone matches and if not then handle it like an international user?
The user's time zone and the user's culture are entirely separate matters.
It's not clear where this code is running, but basically you want to use the appropriate CultureInfo, and then you can use DateTime.TryParse specifying the culture. You can use TryParseExact specifying a standard format of d for "short date format". (Likewise for calls to ToString... just pass in the culture and a format of d.)
Alternatively - and preferably - use a DateTimePicker so you don't need to parse the value at all. (Given your names, it's possible that you're already using a DateTimePicker, so it's unclear why you're calling Convert.ToDateTime - the Value property is already of type DateTime.
Then, don't convert it to a string later either - your VarShipDate property shouldn't be a string property, it should be a DateTime property. That's what you're trying to represent, after all. Avoid string conversions as far as you possibly can. They are error-prone, culturally sensitive, and basically full of potential fail.
Additionally, I would strongly advise against using System.TimeZone - use System.TimeZoneInfo, which is effectively the replacement for TimeZone.
I know that culture rules for dates/numbers is enough for an entire book, I think I have a simple question though..
Does using InvariantCulture basically mean that you explicitly define what culture the value (date/number/whatever) will be inputted/displayed as? And it overrides any other culture setting (such as the user agent's setting)?
If an app is built for an audience of one and only one culture, would it make sense to use InvariantCulture and define how you want values inputted/displayed each time?
Does using InvariantCulture basically mean that you explicitly define what culture the value (date/number/whatever) will be inputted/displayed as?
No. It's just a culture which is a bit like US English, except for a few things like currency sign. It's usually used to format/consume text which is to be understood or was produced by another computer rather than a human.
If an app is built for an audience of one and only one culture, would it make sense to use InvariantCulture and define how you want values inputted/displayed each time?
No, you would use the relevant CultureInfo for that culture. You could also explicitly define the format for dates etc, but that's an orthogonal concern. It may well be best to use one of the predefined standard formats for that culture, but if none of those meet your needs you can always be explicit.
InvariantCulture is Independent of any culture or any factor.
For example if you're using new CultureInfo("en-US") it will get you US English Culture(Which may not be actual US English Culture because OS gives you option to change these setting in Control Panel) it will return the modified version of Culture of "en-US" if any custom formatting applied to it.
In other words InvariantCulture will always gives you a Culture which can never be changed across Systems.
Let's assume you want to serialize some value(say double) and pass to another application or some other thread which is running in different culture leads to serious problems.
Consider the following code
Thread.CurrentThread.CurrentCulture = new CultureInfo("fr");
double source = 455.62d;
string serialized = source.ToString();//455,62 since `, is the decimal seperator` in "fr"
Thread t = new Thread((x) =>
{
double deserialized = double.Parse(((string)x));
Console.WriteLine(string.Format("Deserialized value is {0}", deserialized));//outputs 45562
});
t.CurrentCulture = new CultureInfo("en-US");
t.Start(serialized);
numbers matters more right? consider this string denotes AccountBalance?
Hope this helps
With specific regard to DateTime, the best advice I can give is to use CultureInfo.InvariantCulture for ParseExact and ToString when you have an exact format in mind. (You can also use it with Parse if you happen to know that your input format matches the invariant culture's formats, but I typically avoid this.)
Don't use the invariant culture when interacting with a user.
Keep in mind that the culture contains several items, including the ordering of day/month/year parts, the date and time part separator characters, the character encoding, and the language-specific names of the days of the week, months of the year, and abbreviations including am/pm.
Some examples of when you should use the invariant culture:
Files on disk, especially text files of a predefined format
External APIs, especially JSON or XML
Unit tests, unless you are specifically testing culture issues
Some examples of when you should use a specific culture such as en-US:
User Interface
Reports
How can I get today's date in M/d/yyyy format irrespective of system format of date using C#?
DateTime.Now.Tostring('M/d/yyyy')
is working only if the system date is in format dd/MM/yyyy or M/dd/yyyy but is not working in case yyyy-MM-dd format.
Eg:
if system date is 2013-06-26 then DateTime.Now.Tostring('M/d/yyyy') is converting the date into 06-26-2013 but not in 06/26/2013
Use CultureInfo.InvariantCulture to enforce / as date separator:
DateTime.Now.ToString("M/d/yyyy", CultureInfo.InvariantCulture)
Ideone
Looks like you just need to use CultureInfo.InvariantCulture as a second parameter in your .ToString method.
Console.WriteLine(DateTime.Now.ToString("M/d/yyyy", CultureInfo.InvariantCulture));
Using the invariant culture is the correct solution if you always want the same DateTime to produce the exact same string on multiple systems (or even on the same system due to culture changes). However, be aware that if this is user-visible, you're giving up the possibility of internationalization (for instance, if you display day or month names, they will be in English regardless of what language the user speaks). To only ensure that slashes are not replaced with another date separator, use single quotation marks:
DateTime.Now.Tostring("M'/'d'/'yyyy");
Edit:
Also, if your users are using different date formats, there's a good chance they're also using different time zones. If this DateTime needs to make sense across multiple systems, consider using DateTime.UtcNow. This will also protect you against potential bugs due to a user changing their time zone (when travelling, say) or daylight saving/summer time beginning/ending. If you're just displaying the string to the user at the current instance and not persisting it, DateTime.Now is probably what you want. In that case, however, I'd question why you're trying to mess with the format they've chosen.
Like this:
DateTime.Now.Tostring("M'/'d'/'yyyy");
The apostrofe forces the ToString() method to use the delimiter that you specified.
However, I would let the user choose a culture and use that cultures default formatting instead.