Why are there no char.IsUpperInvariant / char.IsLowerInvariant methods?

Question

Char implements the methods ToLowerInvariant and ToUpperInvariant to transform a character to upper/lower case independent of the current culture. However, there are no IsUpperInvariant and IsLowerInvariant methods. Why?

Answer 1

The following methods are the best you can get:

• Char.IsUpper
• Char.IsLower

Once a character is converted to lower/upper format, whether the conversion was culture specific or not, they will properly detect its case.

On the other hand, you cannot say if a given character is the product of a culture specific or an invariant transformation. You can just look at it and observe that its current case is either lower or upper. Given, for example, the character E obtained from an upper case transformation... how can you say if it originally was ë or e? If you don't know it's original form and the current culture the system is using... you simply can't.