The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
-platforms). The C<no utf8> pragma tells Perl to switch back to treating
+platforms). The C<no utf8> pragma tells Perl to switch back to treating
the source text as literal bytes in the current lexical scope.
This pragma is primarily a compatibility device. Perl versions
Converts (in-place) I<$string> from logical characters to octet
sequence representing it in Perl's I<UTF-X> encoding. Note that this
should not be used to convert a legacy byte encoding to Unicode: use
-Encode for that. =item * $flag = utf8::decode($string)
+Encode for that.
+
+=item * $flag = utf8::decode($string)
Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
into logical characters. Note that this should not be used to convert
Unicode back to a legacy byte encoding: use Encode for that.
+=item * $flag = utf8::valid(STRING)
+
+[INTERNAL] Test whether STRING is in a consistent state. Will return
+true if string is held as bytes, or is well-formed UTF-8 and has the
+UTF-8 flag on. Main reason for this routine is to allow Perl's
+testsuite to check that operations have left strings in a consistent
+state.
+
=back
-C<utf8::encode> is like C<utf8::upgrade> but the UTF8 flag does not
-get turned on. See L<perlunicode> for more on the UTF8 flag and the C
-API functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>,
-C<sv_utf8_encode>, C<sv_utf8_decode> that are wrapped by the Perl
-functions C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
+C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is cleared.
+See L<perlunicode> for more on the UTF8 flag and the C API functions
+C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
+and C<sv_utf8_decode>, which are wrapped by the Perl functions
+C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
C<utf8::decode>.
=head1 SEE ALSO