How do I find "wide characters" printed by perl?

Question

A perl script that scrapes static html pages from a website and writes them to individual files appears to work, but also prints many instances of wide character in print at ./script.pl line n to console: one for each page scraped.

However, a brief glance at the html files generated does not reveal any obvious mistakes in the scraping. How can I find/fix the problem character(s)? Should I even care about fixing it?

The relevant code:

use WWW::Mechanize;
my $mech = WWW::Mechanize->new;   
...
foreach (@urls) {
    $mech->get($_); 
    print FILE $mech->content;  #MESSAGE REFERS TO THIS LINE
...

This is on OSX with Perl 5.8.8.

Answer 1

I assume you're crawling images or something of that sort, anyway you can get around the problem by adding binmode(FILE); or if they are webpages and UTF-8 then try binmode( FILE, ':utf8' ). See perldoc -f binmode, perldoc perlopentut, and perldoc PerlIO for more information..

The ":bytes", ":crlf", and ":utf8", and any other directives of the form ":...", are called I/O layers. The "open" pragma can be used to establish default I/O layers. See open.

To mark FILEHANDLE as UTF-8, use ":utf8" or ":encoding(utf8)". ":utf8" just marks the data as UTF-8 without further checking, while ":encoding(utf8)" checks the data for actually being valid UTF-8. More details can be found in PerlIO::encoding.

Answer 2

If you want to fix up the files after the fact, then you could pipe them through fix_latin which will make sure they're all UTF-8 (assuming the input is some mixture of ASCII, Latin-1, CP1252 or UTF-8 already).

For the future, you could use $mech->response->decoded_content which should give you UTF-8 regardless of what encoding the web server used. The you would binmode(FILE, ':utf8') before writing to it, to ensure that Perl's internal string representation is converted to strict UTF-8 bytes on output.