Java.lang.Character.isUnicodeIdentifierStart() equivalent in .NET

Question

.NET中是否有与Java.lang.Character.isUnicodeIdentifierStart()等效的方法？

Answer 1

There is no method directly for this. In most .NET languages, identifiers can be any Unicode "letter" or an underscore, so you could easily write this as:

bool IsValidIdentifierStart(char ch)
{
    return ch == '_' || char.IsLetter(ch);
}

Note that the CLR is more flexible. The CLS specification, chapter 8.5.1, states:

Assemblies shall follow Annex 7 of Technical Report 15 of the Unicode Standard 3.0 governing the set of characters permitted to start and be included in identifiers, available on-line at http://www.unicode.org/unicode/reports/tr15/tr15-18.html . Identifiers shall be in the canonical format defined by Unicode Normalization Form C.

This allows the runtime to use identifiers that aren't permiitted by many of the standard languages.

Answer 2

You could use Char.IsLetter() as a Unicode Identifier must start with an alphabetical letter...

EDIT: IsLetter() would return true for an underscore, which is invalid, so that should also be checked for.

Answer 3

If you need more than ch == '_' || char.IsLetter(ch) ch == '_' || char.IsLetter(ch) suggested by Reed Copsey than check out Char.GetUnicodeCategory which give you detailed Unicode categorization of a character.