Using Unicode with Perl XS

Table of Unicode-related XS functions

Function name	Source file	Purpose
`UTF8SKIP`	`utf8.h`	Assuming that `buf` is a pointer to the first byte of a UTF-8 encoded string, this takes the first character of `char * buf` and works out how many bytes the encoded character will take up. Uses a table called `PL_utf8skip` also defined in `utf8.h`.
`SvUTF8`	`sv.h`	Checks if the flag `SVf_UTF8` is set in a `sv` (scalar value) structure.
`is_utf8_string`	`utf8.c`	True/false function called in the form is_utf8_string (text, length) which checks if a string is correctly encoded as UTF-8.
`SvUTF_on`	`sv.h`	This C macro turns on the flag in the `SV` (scalar value) which says that the string is Unicode. It does not check whether the scalar value contains UTF-8 or not, so before using this it is necessary to use `is_utf8_string` to check whether the bytes actually are UTF-8 encoded or not.
`SvUTF_off`	`sv.h`	This is like SvUTF_on.