imho, the ternary (?:) operator isn't really meant to perform side effects. It was designed to select from two separate values:

$x = (1 == 1)
  ? 'true'
  : 'false'

[download]

'true' is put into $x if 1==1, and 'false' otherwise. Here's a way that does what you need, still using the ternary operator:

#!/usr/bin/perl

use warnings;
use strict;

use List::Util qw (first);

my @a = qw( 1 2 3 4 5 );
my @b = qw( 9 8 2 1 5 );

my @z;

for my $elem ( @a ){
    my $result = ( first { $elem == $_ } @b )
        ? '+'
        : '-';

    push @z, $result;
}

print @z;

[download]

Output:

++--+

Edit: Changed from using alpha to using numeric as to not confuse the OP with 'eq'.

Update: Please see this post by Anomalous Monk as to why my choice of using first() from List::Util should be replaced with any() from List::MoreUtils. It's a drop-in replacement in fact.

In reply to Re: Failed array attemp by stevieb
in thread Failed array attemp by Anonymous Monk

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