That's wrong.

It doesn't "default to ASCII". It works against decoded text aka string of Unicode Code Points. Always. This can be demonstrated using "\N{U+100}" =~ /\w/ (which matches). You need to use /a if to limit it to the ASCII range.

Text encoded using ASCII happens to work because $x eq encode( "US-ASCII", $x ).

Text encoded using iso-latin-1 happens to work because $x eq encode( "iso-latin-1", $x ) (though do see last paragraph).

Those are just side effects of \w working on decoded text.

There was a bug where \w didn't work for characters in U+0080..U+00FF sometimes. This was fixed 12 years ago in 2011. Add use v5.14; to get the fix.

In reply to Re^12: Seeking Perl docs about how UTF8 flag propagates (Terminology) by ikegami
in thread Seeking Perl docs about how UTF8 flag propagates by raygun

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