I recommend you use strict and warnings, first of all. If you run with warnings, it says:

defined(@array) is deprecated at ...
        (Maybe you should just omit the defined()?)
0
1
Use of uninitialized value in addition (+) at ...
1
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If I remove the "defined", as suggested, it runs as desired.

Yes, there is a bug and you should file a bug. Be sure to CC the author because not all CPAN authors look at their RT queue.

The issue is from this line in the source:

my $target = shift or Carp::croak "No target in member/2 ";
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sub member {
    my ($target, @list) = @_;
    Carp::croak "No target in member/2 " if ! @list;
    if (defined $target) {
        for (0 .. $#list) {
            return $_ if $list[$_] eq $target;
        }
        return $NEG;
    }
    else {
        for (0 .. $#item) {
            return $_ if ! defined $item[$_];
        }
        return $NEG;
    }
}
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It would also be nice if the documentation explicitly reminded the user that since it returns the index (first item = 0), member() should not be used as a boolean.

With regards to your original question - see Getting Matching Items From An Array.

Solution using grep:

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

sub member {
    my $item = shift;
    my @list = @_;
    if (grep {$_ eq $item} @list) {
        return 1;
    }
    else {
        return 0;
    }
}

my @x = (0,1,3);
print member(2,@x),"\n"; # not in list 
print member(0,@x),"\n"; # 1st item in list
print member(2,@x),"\n"; # not in list, again
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Solution using the any function in List::MoreUtils:

#!/usr/bin/env perl
use warnings;
use strict;
use List::MoreUtils qw(any);

sub member {
   my $item = shift;
   my @list = @_;
   return (any {$_ eq $item} @list) + 0;
}

my @x = (0,1,3);
print member(2,@x),"\n"; # not in list 
print member(0,@x),"\n"; # 1st item in list
print member(2,@x),"\n"; # not in list, again
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Both print out:

0
1
0
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Use of "defined" on aggregates (hashes and arrays) is deprecated. It used to report whether memory for that aggregate has ever been allocated. This behavior may disappear in future versions of Perl. You should instead use a simple test for size:

Since you don't actually need an array of results, you might want to do something like this instead:

   my $found;
   ($found) = grep ...;
   if (defined $found) {
      return $found + 1;
   }
   else {
      return 0;
   }
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Brother Monks,


I now understand why the sub failed and have used your ideas to create a correctly working function.

I also submitted a bug report on List::Member at cpan.org.

Thanks!
Johanus