Before I start thank you to Mike Geyser for for bringing this up on Twitter.
Recently I wrote about what is the correct way to display currency in South Africa, which was meant as an interest post rather than anything related to Windows 8 or development – but it seems to be serendipitous in it’s timing. The post referred to the currency format and how you should use a comma to separate Rands & Cents. Windows has always (at least as far back as Windows 98) respected this as the correct currency format in South Africa.
Here you can see Windows 7 (left) and Windows 8 (right) have the same settings.
However with Windows 8, Microsoft have decided to be correct everywhere so if you compare the number format settings in Windows 7 (left) it uses a full stop where Windows 8 (right) uses a comma for number formatting.
The problem is that the number format setting is used in .NET for parsing which means that all numeric code parsing code will break in Windows 8 if you have the South African formatting set!
var testOne = Decimal.Parse("10.2"); // works in Windows 7 and before - exception in Windows 8
var testTwo = Decimal.Parse("10,2"); // works in Windows 8 but fails in Windows 7 and before
The exception that will be raised is: System.FormatException: Input string was not in a correct format.
To be fair, Microsoft has said you should never write code like that, you should always provide the culture settings when parsing (this code always works):
var rightWay = Decimal.Parse("10.2", CultureInfo.InvariantCulture);
There are also two other ways to handle this:
- Add the culture to the config file
- Set culture globally
- With .NET 4.5 you can use the new DefaultThreadCurrentCulture once at the start of your app in code and you will be fine through the rest of the code.
CultureInfo.DefaultThreadCurrentCulture = CultureInfo.InvariantCulture;
var anotherWay = Decimal.Parse("10.2");
In summary when going to Windows 8, make sure you properly test your applications and you test them on the culture that the users will use.
