my $sep_re = quotemeta($sep);

my @fields = split(/$sep_re/, $_);

##</code><code>##

my @fields = split(/\Q$sep/, $_);

##</code><code>##

$\ = "\n";
$, = ";";
for my $sep (",", "\t", "|") {
   my $line = join($sep, qw( a b c ));
   print $line;
   my @fields = split(/\Q$sep/, $line);
   print @fields;
   print '';
}

##</code><code>##

a,b,c
a;b;c

a       b       c
a;b;c

a|b|c
a;b;c

##</code><code>##

$\ = "\n";
$, = ";";
for my $sep ('\t', "\t") {
   print split(/\Q$sep/, "foo\tbar\\tbaz");
}

##</code><code>##

foo     bar;baz
foo;bar\tbaz