use Data::Dumper;

my @list = ();
my $lastc_33 = '';
my $lastd_34='';
my $last_33='';

......
print Dumper $_->{TEST33};
print Dumper $lastc_33;
print Dumper $lastd_34;
print Dumper $last_33;
print Dumper $_->{TEST34};


if( $_->{ TEST33 } eq $lastc_33 && $lastd_34 =~/8/ && $last_33 =~/00/ 
+&& $_->{ TEST34 } =~/7/ && $_->{ TEST33 } =~/00/ )  {

}
else  {
          $lastd_34 = $_->{ TEST34 };
          $last_33 = $_->{ TEST33 };
          push (@list, $_);
       }
[download]

Since you've explicitly initialized a few of the variables, then only the remaining ones are the potential causes for the warnings, namely $_->{ TEST34 } and $_->{ TEST33 }.

Perhaps you might want to check their values prior to the IF statement to ensure they are what you think they are. If either is not initialized, then just don't execute the IF statement.

BTW, that's a fairly complicated piece of logic there. Maybe you might want to break it up into smaller, logical chunks? That way, you'll have a better idea of what you were trying to do six months down the road.

That's why I am confused, I my head the IF should be doing this check, how would I check otherwise?

At the risk of adding more bulk to your code, try this check first, as well as one for $_-> { TEST34) }.

if ($_->{ TEST33 } ) {
  <your previous code here ...>
}
[download]


Your wish is my commandline.

Where does $_ come from? Are those keys defined in the hash it references?

Yes it is!


$data = ();
   $sql = sprintf $sql_fmt, $account->[$i]{ 'ACCOUNT#' };
   $data = exec_select( $sql );


foreach (@$data) {
....
[download]

From this snippet and the first one I can understand that data is an array that references hashes. This last snippet shows that data may be defined with the result of the call to exec_select. Still, that shows no guarantee that the hashes in data have the keys $_->{TEST34} and $_->{TEST33}. You may be assuming that they are present, but they are not.