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Postings from February 2007
demerphq skribis 2007-02-08 13:38 (+0100):
> Not sure. Since pos would only be updated on a successful match, and
> both the pattern and string would be in utf8 doesnt it mean that the
> pos would be set to a valid utf8 sequence start?
The trouble is that pos() normally returns a *character* index, not a
*byte* index.
juerd@lanova:~$ perl -le'use utf8; ($a = "f€oo") =~ /o/g; print pos($a)'
3
If $a is the 4 character unicode string, pos must be 3. But if you
ignore that it's UTF8 internally, it will be 5, or has to be
re-calculated after the succesful match (which is a performance hit again).
juerd@lanova:~$ perl -le'($a = "f€oo") =~ /o/g; print pos($a)'
5
# $a is a 6 byte string, no euro sign there, but three bytes
# representing it in UTF8.
Note that I say all this without knowledge of the actual internals.
Perhaps the actual internal pos value is already in bytes only, and
recalculated to characters only when needed.
--
korajn salutojn,
juerd waalboer: perl hacker <juerd@juerd.nl> <http://juerd.nl/sig>
convolution: ict solutions and consultancy <sales@convolution.nl>
Ik vertrouw stemcomputers niet.
Zie <http://www.wijvertrouwenstemcomputersniet.nl/>.