Extracting the quoted strings and then searching for them again is kind of inefficient. Likewise for having to create a new regexp for every single quoted string. Perl goes to a fair amount of trouble to compile a regexp into something that walks through a string; the whole point of that is so that you can re-use that walk routine lots of times.
Meaning what you really want is a single regexp fixed in advance that gets applied to every line. Bonus points if you can have it be a walk-thingie that only has to do a single pass through the string (which then means you want to think about how you'd do the walk if you had to do it yourself). Try this
use strict; use warnings;
while ( my $line = <DATA> )
{
print "# ORIG: $line";
if ($line =~ m/"/g) {
$line =~ s/\G([^,"]*(?:"[^"]*"[^",]*)*),/$1|/g;
}
print "# NEW: $line";
}
__DATA__
ONE,"TWo,2",Three,Four,Five
ONE,"$TWo,2",Three,Four,"Fi,ve,,"
ONE,"$TWo2","Three,(3)",Four,Five
ONE,"$TWo2","Three,(3",Four,Five
