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sub print_array {
  my $array = shift;
  print "( ";
  foreach $item (@{$array}) {
    print "$item , ";
  }
  print ")\n";
}

my @array; # initialize
my $array_ref = @array;
print_array( $array_ref);

The developer mistakenly left out the \ indicator when initializing $array_ref. Consequently, instead of a reference to the array, it contains the number of elements in the array. When passed to the print_array() subroutine, this program prints an empty array.

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my $array_ref = \@array;
print_array( $array_ref);

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my @array; # initialize
my $cardinality = @array;
print "The array has $cardinality elements\n";

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my $cardinality = scalar( @array);
print "The array has $cardinality elements\n";

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my $cardinality = $#array + 1;
print "The array has $cardinality elements\n";

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Automated Detection

Bibliography

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[Beattie

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]
[CPAN]	Elliot Shank, Perl-Critic-1.116, ProhibitBooleanGrep
[Conway 2005]	"Lists," p. 71
[Wall 2011]	perlfunc

 

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Image Added Image Added Image Added|http://search.cpan.org/~elliotjs/Perl-Critic-1.116/]. [ProhibitBooleanGrep|http://search.cpan.org/dist/Perl-Critic/lib/Perl/Critic/Policy/BuiltinFunctions/ProhibitBooleanGrep.pm]. \[[Conway 2005|AA. Bibliography#Conway 2005]\], pg 71 \[[Wall 2011|AA. Bibliography#Manpages]\] [perlfunc|http://perldoc.perl.org/perlfunc.html]Image Removed      02. Expressions      EXP30-PL. Do not use deprecated or obsolete functions