Usually only when a string is operated on with data that itself has the utf8 flag on. In perl5.8.0 (but not any later version) this can include input from a file if you are using a utf8 locale.

Once the flag is on, does 

use Data::Dumper;
$Data::Dumper::Useqq = 1;
print Dumper $string;

[download]
show any > 8bit characters? (e.g. "foo\x{1ff}bar"). If so, where does it come from? If not, upgrading perl, using a non-utf8 locale, or binmode'ing your input filehandles may help.

In reply to Re: When is the utf8-flag turned on? by ysth
in thread When is the utf8-flag turned on? by uwevoelker

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