Here are two other potential solutions.

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
[download]

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
[download]

Both print out:

0
1
0
[download]