Hi Rickman1! Let me start by cleaning up a little bit and then explaining after. 
#!/usr/bin/env perl

use strict;
use warnings;
use List::Util 1.45 qw(uniq);

my $char_at=10;
my $num_chars=50;
open my $fh, '<:encoding(UTF-8)', $ARGV[0]
    or die "Could not open '$ARGV[0]' $!";
my @trnAccounts;
while (my $line = <$fh>) {
    chomp $line;
    next unless $line && length($line) >= $char_at;
    push @trnAccounts, substr($line, $char_at, $num_chars);
}

my @unique_accounts = uniq(@trnAccounts);
for my $i (0..$#unique_accounts) {
    print $i, ":", $unique_accounts[$i], "\n";
}
print "total: ", scalar(@trnAccounts), "\n";
print "uniq : ", scalar(@unique_accounts), "\n";

[download]
Some of the ways you were using trim() and putting elements into an array were off. Once cleared up, the code above should hopefully be a little easier to follow. Also, later versions of List::Util contain a uniq function. Use that instead. Hope that helps.

In reply to Re: Trying to print out only unique array values- by genio
in thread Trying to print out only unique array values- by rickman1

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