Re: compare two strings and return only he unique values.

[blue_cowdawg]

I am trying to display unique values from two strings "ABCDE", "BCDEO" to return "AO" with the below code

#!/usr/bin/perl -w 

use strict;
use warnings;
my $string1="abcdef";
my $string2="defghi";

my @ary=split(//,$string1);
push @ary,split(//,$string2);
my %een=();

map{ $een{$_}++ } @ary;
my @unique=();
foreach (@ary){
    next unless $een{$_} == 1;
    push @unique,$_;
}

printf "%s\n",join(",",@unique);

Hashes are our friends....

[Kenosis]

Won't show "a" when:

my $string1="abcdefa";
my $string2="defghi";

[blue_cowdawg]

Won't show "a" when:

That's because "a" isn't unique. :)

printf "%s\n",join(",", keys %een);

would show "a" and all the other letters once.

[Kenosis]

Your code quite effectively forms a union of the two strings' characters. However, the OP's request was to 1) compare two strings, and 2) return only the unique values. Where does your code compare the two strings? Forming a union of their characters does not compare the two strings. In fact, if we strictly regard their union as a non-multiset of characters, "a" is unique, since (set notation): {a} = {a,a} = {a,a,a}. Thus, "a" should still appear in their union--even with two occurrences within one string.

As has been point out, the OP's specs are equivocal, yet I tend to favor "unique" as meaning a character (replicated or not) that only belongs to one or the other string (i.e., "unique to")--and is not in both.