PHP. Руководство по PHP. 2005
mb_regex_encoding
mb_regex_encoding
Description
mixed mb_regex_encoding ([string encoding])mb_regex_encoding() returns the character
encoding used by multibyte regex functions.
If the optional parameter encoding is
specified, it is set to the character encoding for multibyte
regex. The default value is the internal character encoding.
See also: mb_internal_encoding(),
mb_preferred_mime_name
mb_regex_set_options
Отвечу на любые вопросы. С уважением, Дмитрий Владимирович.