PCRE provides basic Unicode support. When a pattern is compiled with the PCRE_UTF8 flag, the pattern will run on Unicode text. However, PCRE has no capability to recognize any properties of characters whose values are greater than 256.

PCRE determines case and the property of being a letter or digit based on a set of default tables. You can supply an alternate set of tables based on a different locale. For example:

setlocale(LC_CTYPE, "fr");
tables = pcre_maketables(  );
re = pcre_compile(..., tables);