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.

In reply to Re^4: compare two strings and return only he unique values. by Kenosis
in thread compare two strings and return only he unique values. by Learnlot1

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.