.NET: Are there any differences between InvariantCulture and en-US?

Question

Given the following two cultures:

CultureInfo c1 = InvariantCulture;
CultureInfo c2 = new CultureInfo("en-US");

and i were to examine every piece of information specific to both cultures, e.g.:

c1.DateTimeInfo.ShortDatePattern;
c2.DateTimeInfo.ShortDatePattern;

c1.DateTimeInfo.LongDatePattern;
c2.DateTimeInfo.LongDatePattern;

c1.NumberFormat.CurrencyDecimalDigits;
c2.NumberFormat.CurrencyDecimalDigits;

c1.TextInfo.IsRightToLeft;
c2.TextInfo.IsRightToLeft;

Would i find any differences?

In other words, is the InvariantCulture, for all purposes, identical to the "en-US" culture?

Footstone

Are you asking this merely as a curiosity? Each culture has specific use cases, which are clearly defined. Whether they happen to be the same or not is irrelivant to the process of writing software. – Lamori

i was asking because i wanted to know if i can use InvariantCulture when i really mean "i dunno what culture. What am i, Google?!" If i am trying to parse a date, or a money value, or a number, i don't what culture it is in. And even here in en-US, there are a number of different ways of writing a date. How do i know what subculture of en-US the person meant? So by asking for differences between them, i was seeing how often i can get away with using InvariantCulture, rather than forcing the CurrentThreadCulture, CurrentUICulture or CurrentCulture. – Footstone

I would recommend not trying to get away with anything. The current culture should be used for everything that doesn't need to be invariant across machines or changes in culture. If you are attempting to parse data that you have no control over and that doesn't match the current culture, doesn't conform to a particular format, and doesn't tag the culture that was used to create it, then, perhaps, the culture should be user-selectable or something. I don't think Invariant is going to help you. – Lamori

Answer 1

Yes.

For example: InvariantCulture uses the international symbol for currency: "¤" versus the dollar sign: "$" when formatting currency.

For the most part, however, they're very similar.

Thumbtack

To quote MSDN: “The InvariantCulture property represents neither a neutral nor a specific culture. It represents a third type of culture that is culture-insensitive. It is associated with the English language but not with a country or region.” ... Thus it makes sense to behave for the most part as English (though for the weird US date format I would have loved to see something sane) but the currency would just be nonsense :) – Winny

Drat. So trying to parse a money string with the InvariantCulture will work nowhere in the world. – Footstone

@IanBoyd, it's good actually. So no one will mistakenly try to parse local money string using the InvariantCulture. What really makes InvariantCulture useless is awkward M/d/yyyy instead of normal yyyy-MM-dd. – Isadora

@Isadora Depends on your definition of awkward. For example September 11th happened on 9/11. – Footstone

@IanBoyd, the thing is that it's not culture invariant (it's exactly the opposite – tied to specific cultures; unlike, for example, ISO 8601; and untying currency symbol while tying the date/time format looks quite inconsistent for me). – Isadora

@Isadora But the invariant culture isn't tied to any specific culture. Cultures formats can (and have) changed, but the Invariant culture remains invariant. – Footstone

@IanBoyd, yep. That's an additional reason why resembling culture-specific values (instead of some common standard values) in a culture-invariant thing (or at least in a thing designed to be so) was, IMHO, not the best choice. – Isadora

Answer 2

There are some actual differences (check both values in a Watch window), but the most relevant difference is the intent. InvariantCulture shows your intent of parsing some data in a culture independent, if english related, manner, whereas en-US declares your actual intent to parse data in a US specific manner.

Species

Answer 3

Well, if you look at what your snippet of code might produce:

CultureInfo c1 = CultureInfo.InvariantCulture;
CultureInfo c2 = new CultureInfo("en-US");

Console.WriteLine( c1.DateTimeFormat.ShortDatePattern.ToString());
Console.WriteLine( c2.DateTimeFormat.ShortDatePattern.ToString());

Console.WriteLine( c1.DateTimeFormat.LongDatePattern.ToString());
Console.WriteLine( c2.DateTimeFormat.LongDatePattern.ToString());

Console.WriteLine( c1.NumberFormat.CurrencyDecimalDigits.ToString());
Console.WriteLine( c2.NumberFormat.CurrencyDecimalDigits.ToString());

Console.WriteLine( c1.TextInfo.IsRightToLeft.ToString());
Console.WriteLine( c2.TextInfo.IsRightToLeft.ToString());

You'll see some differences:

MM/dd/yyyy
M/d/yyyy
dddd, dd MMMM yyyy
dddd, MMMM dd, yyyy
2
2
False
False

And just think, when the US loses it's backbone and decides to start using European style dates or moves to the metric system (the metric system is the tool of the devil! My car gets forty rods to the hogshead and that's the way I likes it!), the InvariantCulture can just coolly and smoothly stay the way it is. So all those dates you've stashed away in a database in text form using the InvariantCulture will continue to just work...

Sleuth

Answer 4

It is very important to consider the intent of the data. If you are serializing make sure to use InvariantCulture.

See: http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo.aspx

From the microsoft documentation:

Dynamic Culture Data

Except for the invariant culture, culture data is dynamic. This is true even for the predefined cultures. ...

Caution

When saving data, your application should use the invariant culture, use a binary format, or use a specific culture-independent format. Data saved according to the current values associated with a particular culture, other than the invariant culture, might become unreadable or might change in meaning if that culture changes.

I just encountered this recently where the user had his Region and Language settings set to English (United States), but had chosen his personal date format to dd-MMM-yy. He received a project from a client with a date in the default en-US format "4/29/2010 1:45:30 PM" and the code:

customValue = DateTime.Parse(customValue.ToString(), CultureInfo.CreateSpecificCulture("en-US"));

threw an exception because his local preferences override what the typical en-US format.

Inhumane

+1 for: "If you are serializing make sure to use InvariantCulture." and to be very very accurate: if you are deserializing, then too. – Cliff

Answer 5

Short answer yes. InvariantCulture is what it says, not a specific culture. It is english, but not a specific region

you can read more about it here : MSDN

Nilson

Answer 6

I know they have a different CultureName and LCID (see this list).

Additionally, the currency symbols are different - ¤ for InvariantCulture and $ for en-US.

From InvariantCulture:

It is used in almost any method in the Globalization namespace that requires a culture.

Suggesting that for the most part, they are interchangeable. However, the names do state intent, so you should think about that when using CultureInfo.

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