Question

Is there a C++ function available that decides if a given Unicode point is a letter? I mean what’s often described as \p{L} in regular expressions. So it could be a Latin, Greek, Cyrillic or other letter, as opposed to punctuation, numbers, etc., which, in unicode are also be represented by several other large code point ranges.

So what I’m asking for a function similar to this:

bool isUnicodeLetter(int32 codepoint);

Maybe in the boost or ICU libraries?

Answer 1

In ICU4C, the function is called u_isalpha():

UBool u_isalpha(UChar32 c)

Determines whether the specified code point is a letter character.

True for general categories "L" (letters).

But be careful when using this as it is easy to misuse. u_isalpha() and the other functions in uchar.h are only designed to provide low-level access to Unicode character data.