The grep command can do the kinds of things you're looking to do.

#!/usr/bin/perl
use warnings;
use strict;

my @isbn = ();
my %hash = ();
for ( 0 .. 100) {
   $isbn[$_] = &gen_isbn_13; 
}
push @isbn, "9780523456789";
push @isbn, "9780523412345";

while(my $pattern = <DATA>) {
    chomp($pattern);
    print "Testing pattern = $pattern\n";
    $hash{$pattern} = &isbn_exists( $pattern, \@isbn );
    print "Matches found! ISBN = $_ \n" for ( @{$hash{$pattern}} );
}

sub isbn_exists {
    my $pattern = shift;
    my $isbn_arrayref = shift;
    my @answer = grep { /\Q$pattern\E$/ } @{ $isbn_arrayref };
    return \@answer;
}

sub gen_isbn_13 {
    my $num = "978";
    for ( 1 .. 10 ) {
        my $digit = int(rand(10));
        $num .= $digit;
    }
    return $num
}
__DATA__
12345
97833
97810
97805

[download]
One run of the program looks like:

C:\Code>perl isbncheck.pl
Testing pattern = 12345
Matches found! ISBN = 9780523412345
Testing pattern = 97833
Testing pattern = 97810
Testing pattern = 97805

[download]
Update: More exact match to original pattern

In reply to Re: Possible to use an expression as the hash key with exists? by dwm042
in thread Possible to use an expression as the hash key with exists? by wenD

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.