Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

Get the Key corresponding to any given value

( #177969=categorized question: print w/ replies, xml ) Need Help??
Contributed by rmalhotra on Jun 28, 2002 at 09:11 UTC
Q&A  > hashes


Description:

Is there any way to get the key corresponding to a given value from a hash table

Answer: Get the Key corresponding to any given value
contributed by jsprat

If the values are unique:

my %rhash = reverse %hash; my $key = $rhash{$value};

will give you the key for a given value.

If you might have duplicate values, grep is your friend:

my @keys = grep { $hash{$_} eq $value } keys %hash;

If your values are numeric, use "==" instead of eq.
Answer: Get the Key corresponding to any given value
contributed by manav

Most of these cases have been covered in the perlfaq itself. See How do I look up a hash element by value?

Answer: Get the Key corresponding to any given value
contributed by simmisam

my ($key) = grep {$value ~~ $hash{$_}} keys %hash; print "Key = $key\n";

Please (register and) log in if you wish to add an answer



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • 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, 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, 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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others cooling their heels in the Monastery: (5)
    As of 2015-07-06 05:04 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









      Results (70 votes), past polls