Get the intersection of two lists of strings in Perl

Question

In Chapter 4, Section 4.8 (Computing Union, Intersection, or Difference of Unique Lists), the Perl Cookbook provides this technique for getting the intersection of two lists

Answer 1

Smallest amount of change required from the original solution. Just lower-case the strings.

@a = qw( a b c d );
@b = qw( C D E F );
...
foreach $e (@a, @b) { 
    $union{lc $e}++ && $isect{lc $e}++ 
}

@union = keys %union;
@isect = keys %isect;