use strict;
#use warnings;

for my $s ( qw( nob bob cob bob dob ) )
{
    my $name = $1 if $s =~ /(bob)/;
    warn $name || 'undef';
}

##</code><code>##

undef at - line 7.
bob at - line 7.
undef at - line 7.
bob at - line 7.
undef at - line 7.