Enable Chinese usernames in Wordpress registration

enable-chinese-characters-usernames.php

function sanitize_chinese_user( $username, $raw_username, $strict ) {
	if ( $username != $raw_username ) {
		$username = $raw_username;
	}
	$username = strip_tags( $username );

	// Kill Chinese characters
	$username = preg_replace( '|[^a-z0-9 _.\-@一-龥]|ui', '', $username );

	// Consolidate contiguous whitespace
	$username = preg_replace( '|\s+|', ' ', $username );

	return apply_filters( 'sanitize_chinese_user', $username, $raw_username, $strict );
}

add_filter( 'sanitize_user', 'sanitize_chinese_user', 1, 3 );