Is Int32.ToString() culture-specific?

Question

I'm running a beta version of ReSharper, and it's giving me warnings for the following code:

int id;
// ...
DoSomethingWith(id.ToString());

The warning is on the id.ToString() call, and it's telling me "Specify a culture in string conversion explicitly". I understand the warning, and I know how to fix it -- just change the code to the much more unwieldy id.ToString(CultureInfo.InvariantCulture).

But my question is: is that necessary? I mean, obviously it's important to specify the culture when you're using types like DateTime (different cultures have different date formats) and Double (different characters used for the decimal point). But Int32.ToString(), at least in the en-US and invariant cultures, doesn't add any formatting at all. No commas, no decimal points, no dollar signs, nothing. So what would there be to vary by culture?

Are there some cultures that actually add some sort of formatting when you call the parameterless Int32.ToString()? Or is this a bug in the ReSharper beta, and this warning really isn't applicable to Int32 (in which case I'll file a ReSharper bug report)?

Answer 1

The Operating System allows to change the negative sign for numbers.

Control panel -> 
   Language and regional settings -> 
         Additional settings -> 
             Negative sign

So, current culture could have overridden the negative sign. In this case you need to respect the regional settings, this is the reason of the warning. You can also change the negative sign programatically:

    CultureInfo culture = Thread.CurrentThread.CurrentCulture;
    // Make a writable clone
    culture = (CultureInfo) culture.Clone();
    culture.NumberFormat.NegativeSign = "!";

Answer 2

As tested on a random sample of ints, all 352 cultures installed with Windows (CultureTypes.InstalledWin32Cultures) give identical results.

Daniel is right to note a custom culture could use a different prefix for negative numbers, but I doubt anyone has ever used this feature save by accident.

I guess the .NET devs did it to be consistent with float and other types. What else were they expecting?

> int.MaxValue.ToString(CultureInfo.AncientRome)
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM....

Answer 3

Yes. It depends on the current culture. From the MSDN docs:

The return value is formatted with the general numeric format specifier ("G") and the NumberFormatInfo object for the current culture.

emphasis mine

Resharper just most likely wants you to be explicit about what culture you are intending to use. Since omitting it relies on behavior that may change when executed on different machines.

Answer 4

It's weird; I would have expected 50.ToString(CultureInfo.CreateSpecificCulture("ar-AE")) to return "٥٠", but it doesn't.

I've just looked this up, and the problem seems to be that NumberFormatInfo.DigitSubstitution isn't actually implemented

The DigitSubstitution property is reserved for future use. Currently, it is not used in either parsing or formatting operations for the current NumberFormatInfo object.

So, although there is an enumeration System.Globalization.DigitShapes, it's not actually implemented in the NumberFormatInfo bit of IFormatProvider.

Answer 5

I would have said no, but on checking MSDN Int32.ToString() there's this:

The return value is formatted with the general numeric format specifier ("G") and the NumberFormatInfo object for the current culture.

So there's a surprise.

The question should be why doesn't the current Resharper suggest this?

Answer 6

Because integers can be be as high as 2,147,483,647.

In some countries, they would use decimals or a space in place of the commas.