I've seen a lot of time about Culture-insensitive and Culture-sensitive i don't Knew exactly what are The difference between them.
In some books they divide the Specifiers into Two categories:
Culture-insensitive date/time format strings and
Culture-sensitive date/time format strings
I knew the specifiers but I have no idea abut sensitive and insensitive.
could anyone guide me in this?
To start, I would refer you to .NET Globalization & Localization for more information.
There are certain values/entities that get treated differently in different countries and regions. Such entities include currency symbol, digit separators, dates and more. When displaying this data to your user, you have to format it in a way that makes sense to them. If for instance you display money in a loan amortization application as follows:
Console.WritLine("$" + amount.ToString());
this will only work well in countries that use dollars. And there's no other formatting. To make this culture sensitive, you will have to do it this way...
Console.WriteLine(amount.ToString("C"));
By doing it that way, .NET will use the correct currency symbol, digit separator and decimal point for the culture the application is run in.
There are cases in which you will need to show such data in a specific culture. Doing it this way will change the way it is displayed, you can however provide the culture to use in the following way...
static void Main(string[] args)
{
decimal foo = 23434534.53M;
Dump(foo);
var culture = CultureInfo.CreateSpecificCulture("en");
CultureInfo.CurrentCulture = culture;
Dump(foo);
culture = CultureInfo.CreateSpecificCulture("es");
CultureInfo.CurrentCulture = culture;
Dump(foo);
culture = CultureInfo.CreateSpecificCulture("en-ZA"); // South Africa
CultureInfo.CurrentCulture = culture;
Dump(foo);
}
static void Dump(decimal value)
{
Console.WriteLine(value.ToString("C"));
Console.WriteLine(DateTime.Now.ToLongDateString());
}
When you change the culture at run time, subsequent calls to display the value as money will change the currency symbol, the location of said currency symbol in some cases, the digit separators and the decimal point.
This also affects how dats are displayed as you can see.
You can also use this to change the text displayed in your UI. If you have an app that supports multiple languages, for instance US English, British English, Spanish and French you are not required to know these languages beforehand. Also, you can no longer hard code you string literals like "First name:". Some simple things may differ like the spelling of color (UK English colour). Such things might be inconsequential to someone who doesn't speak English but are taken seriously in the respective countries. If your app is showing children the correct spellings for instance, you want it to get it right for the place it is in.
In this case you can set a UI culture and use resource (resx) files to place your strings in. At runtime you load your strings from the resource files and the .NET runtime can load the correct resx file based on the culture it detects the PC is set to. If there is no match, it will fall back to your default culture.
In my test app I created 2 resource files, one called Strings.resx and the other Strings.es.resx. The first will be the default language, and the other is for Spanish. When greeting a user, I won't have to hard code the greeting but can use it as follows
static void Main(string[] args)
{
Console.WriteLine(ConsoleApp1.Strings.HelloString);
CultureInfo.CurrentUICulture = CultureInfo.CreateSpecificCulture("es");
Console.WriteLine(ConsoleApp1.Strings.HelloString);
}
resulting in the following
Together these techniques can help you create an application that is sensitive to the language and culture of the user. If you need to override that, you can also do that knowingly by specifying which culture to use when presenting your data. Hard coding the entities that vary is not culture sensitive and will display the same regardless of the locale of the machine it is run on.
Culture-sensitive operations should be used when interacting directly with users. Culture-insensitive operations should always be used when interacting with back-end processes and interchange systems, including persisting data. The data that backs culture specific operations can change for many reasons. The data that backs culture-insensitive operations never changes and so is safe to persist and interchange.
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.
In dotnet, the recommended way of formatting currencies in a culture-specific way, is (as far as I can find):
using System.Globalization
var info = CultureInfo.GetCultureInfo("en-GB")
return string.Format(info, "{0:c}", 1234.5678)
This returns:
£1,234.57
However. No specific currency is given here. So if Great Britain ever converts to Euro, the same method would suddenly return something like:
€ 1,234.57
This has just happened to Latvia. This year, it converted to the euro. Various systems contain both amounts in letvian lats and euros. I need to be able to still print and format old currencies. And I need to be sure new currencies can also be handled. This formatting is not just about the symbol, but also about the placement (before, after, with or without space) and the local number format (decimal separator and thousands separator).
Every amount in our database has a currency (e.g. EUR) and a corresponding culture (e.g. nl-NL). Euro amounts are formatting differently depending on if they originate from our German or our Dutch office. (they both use euros, but format the amounts differently)
Does dotnet provide access to older currencies?
What is a future-proof way of writing the formatting amounts?
Right now, the only way I can think of, is to copy the culture-database to my database.
You can create a custom CultureInfo (by cloning one and modifying) which uses a different currency symbol/format (ie. set its NumberFormat to a different instance of NumberFormatInfo).
Then pass this CultureInfo to formatting functions as needed.
As the comment to the question notes, .NET (and Windows in general) doesn't provide historic data (similarly for time zones but there's a library for that). In the cases you need you'll need to hold enough data yourself.
Remember ISO-4217 currency codes are not reused under such a change, so holding that against amounts allows you to format correctly. Additionally just because a country formats their currency amounts one way doesn't mean everyone does. Eg. 25 French Francs was be "FF25.00" in the UK but "25FF00" or "FF25,00" in other locales. (EDIT: I note you covered this last paragraph in the question.)
Of course, the simplest way is to not use the locale-specific currency format, but rather to format the amount as a simple number and pre- or suffix it with the ISO currency code. The convention
------------
Sum: ATS 1.376,00 (= EUR 100,00)
is commonly found on invoices (using locale de-AT as an example).
If you want to use the built-in currency formatting options, I would suggest to replace the currency symbol with the one stored in the database. I.e., in your currency table, you'd need to map currencies to symbols:
EUR -> €
ATS -> S
...
and then you'd replace myCultureInfo.NumberFormat.CurrencySymbol with the one in the database. That way, you ensure that a value is never shown with the wrong currency symbol.
If you are targeting Windows 8 or above, this deficiency is addressed by the Windows.Globalization.NumberFormatting.CurrencyFormatter. It requires that you provide the explicit currency and you can also explicitly provide a language.
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
This should be simple but I cannot find the answer anywhere.
On our asp.net MVC site, we show currency values and I need these currency values to Always be in USD regardless of the users culture settings.
If I use string.format("{0:C}",value) then it shows the value in what ever culture the use has set.
This is incorrect for us as $1000.00 is not the same thing as 1000.00 euro
I still need to use the language side of this, meaning if they are in France I want to use the French localization resource, so I don't want to completely disregard their culture settings, but how can I make sure the currency is always shown in USD?
Explicitly pass culture to the Format call:
string.Format(new CultureInfo("en-US"), "{0:C}",value)
If you have to mix it with other languages - save result of formatting currency value and insert into other places as string.
Side note: using "en-US" (or any other hard-coded culture) will lead to potentially mismatched representation of negative values i.e. some cultures use -100, while other (100) for negative amounts.
You would have to specify CurrentCulture to be en-US and leave CurrentUICulture as is.
I usually do this in global.asax.cs in the Application_BeginRequest event
System.Threading.Thread.CurrentThread.CurrentCulture =
new System.Globalization.CultureInfo("en-US", false);
It is possible to specify the culture in web.config file but that has one drawback - it takes into account the customized regional settings of the server (if the administrator changed the currency or date format on the server for the en-US culture, it would get picked up this way) - so you can't ever be sure that the application will behave exactly the same as when you created/tested it.
When formatting a string as opposed to a DateTime, does the culture ever come into play? Are there any examples of strings that would be formatted differently with two different cultures?
I don't believe so in the current Framework. But if Microsoft ever implements this suggestion on the Connect feedback site, it includes a suggestion to have a format specifier to force upper case:
String.Format("{0:U}", "SomeString") => "SOMESTRING"
Such formatting would be culture-specific.
If you are displaying a string that is stored as a resource it will make a difference if you have separate strings for different cultures (you'd use CultureInfo.CurrentUICulture). For example error messages accessed via a ResourceManager.
String.Format("{0}", "This string") - which I believe is what you're implying by your question, is not affected by the culture.
There are many scenarios when you need culture based formatting.
For example: - Number Format
5.25 in English is written as 5,25 in French
So, if you want to display French formatted number in your program which is in English culture the culture based string format comes into action.