The original code searched for the substrings case insensitively so you'd have to uc() or lc() the strings before passing to index() if you want to behave the same. There is also one more thing that might be worth trying. We might create a character bitmap of all strings beforehand and then only search for the substring if the longer string contains all the characters that the substring does: 

use strict;
use Bit::Vector;

my @data = qw/a mnk ab m b bc abcd cd bcd bd m nk/;
@data = sort {length($b) <=> length($a)} @data;

@data = map [$_, uc($_), Bit::Vector->new_Enum(256, join(',', map ord(
+$_), (split //, uc($_))))->Block_Read()], @data;

my @result = ();
while (@data) {
    push @result, $data[0][0];
    @data = grep { ($data[0][2] & $_->[2]) ne $_->[2] or index($data[0
+][1], $_->[1]) == -1 } @data;
}

print "@result\n";

[download]
Whether and how much would this help depends on the strings. In this case I saved just 5 calls to index() from the original 18.

Jenda
We'd like to help you learn to help yourself
Look around you, all you see are sympathetic eyes
Stroll around the grounds until you feel at home
   -- P. Simon in Mrs. Robinson

In reply to Re^2: Seeking the longest string in an array by Jenda
in thread Seeking the longest string in an array by johnnywang

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