Re: [perl #24541] substr and utf8 and use bytes

William R Ward (via RT) <perlbug-followup@perl.org> writes:

> We have a need to take a string containing utf8-encoded multibyte
> characters, and then, treating the string as bytes, extract a
> substring of N characters from it.
> 
> This is what "use bytes" was meant for, and it works great on Perl
> 5.6.1. 

"use bytes" is evil.  It exposes internal implementation details that
you are not supposed to know about and I'm not surprised the results
differ between versions of perl.

Just use Encode to clearly state your intents in a way that will work
whatever internal representation of wide chars Perl might have.
Something like this:

  substr(encode_utf8($string), $m, $n);

will do what you describe above.

Regards,
Gisle

• [perl #24541] substr and utf8 and use bytes by William R Ward
• Re: [perl #24541] substr and utf8 and use bytes by Gisle Aas
• Re: [perl #24541] substr and utf8 and use bytes by Matt Sergeant
• [perl #24541] substr and utf8 and use bytes by Karl Williamson via RT
• Re: [perl #24541] substr and utf8 and use bytes by SADAHIRO Tomoyuki
• [perl #24541] substr and utf8 and use bytes by Karl Williamson via RT
• Re: [perl #24541] substr and utf8 and use bytes by Bill Ward