$cl_data_row[$x] is unpopulated but no error here under Ubuntu & 5.8.7 with your script:

ww@GIG:~/pl_test$ perl -c countde.pl
countde.pl syntax OK
ww@GIG:~/pl_test$ perl countde.pl
starting script...count is 5
row element is
row element is
row element is
row element is
row element is
ww@GIG:~/pl_test$
[download]

Your line 17 isn't doing what you want/expect. @cl_data_row remains undef Compare:

(Replaces your 17) my $cl_data_row=(\split(/\$de/,$inp_row));
(added) print "\$cl_data_row is $$cl_data_row\n";
[download]

from which the output is:

ww@GIG:~/pl_test$ perl countde.pl
starting script...count is 5
$cl_data_row is per|l|mo|nks|rock|s
[download]

BTW, your chop in line 15 isn't doing what I suspect you think: it's removing the last character, the "s" in "rock|s"