The other answers are all cool for arrays, but maybe using an array is wrong in the first place. Perl has a data type specialized for fast lookups, the hash (denoted by a % in front of the variable name). A lookup of an element in a hash is very fast, while grep and the likes have to go through the whole array, which is slower.

There are some drawbacks to hashes as well, first, they require you to change your code and second and more importantly, a hash dosen't preserve the order of elements - you can't get the elements back from the hash in the order you put them into the hash.

If the above drawbacks are no problem with you, you might want to use the following code : 

  #!/usr/bin/perl -w
  use strict;

  my %elements;
  my $element = "foo";

  # Fill up our hash a bit
  foreach ("bla", "blubb", "foo", "bah") {
    $elements{$_} = 1;
  };

  # now check if $element is in our hash :
  print "Found '$element'\n" if (exists $elements{$element});
  print "D'oh - '$element' not found\n" unless (exists $elements{$elem
+ent});

  # You can still get to all elements in %elements :
  foreach (keys %elements) {
    # but they are in some weird order ...
    print "$_\n";
  };

[download]

In reply to Re: How to find out if X is an element in an array? by Corion
in thread How to find out if X is an element in an array? by juahonen

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.