Perl reads UTF-8 nativly. Regular expressions are for finding characters of interest. So, something like:

require 5.6;
use strict;
use warnings;
use utf8;

my $count;
while (<>) {
   while (/[^\x{1}-\x{7f}]/g)  {
      ++$count;
      print "Found on line $.: $_";
      }
   }
print "Total: $count offending chars found.\n";
[download]

That is, a pattern matches on anything that's NOT in the range of code points 1 through 0x7f, inclusive. The \x{1234} notation matches the UTF-8 encoding of code point 0x1234, all several bytes of it.

Want to track which ones they are, not just count them all? Try something like ++$chars{$&}; inside the inner loop.

See perlvar for the meaning of $&, the utf8 page for the pragmatic module, and perlre for regular expressions. See the latter half of perlmod for "Perl Modules" (the beginning might just make your eyes glaze over as yet). See "Quote and quote-like operators" in perlop for \x and friends.

Now, care to tell us precicely what each line means in that example (after fixing typos)? Take you're time, we're always open.

—John

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