Re^2: How to use a negative backreference in regex?

[larryk]

in reply to Re: How to use a negative backreference in regex?
in thread How to use a negative backreference in regex?

thanks - it's been a while :)

I eventually ended up with the following:

my $unique = qr/^(.)(?!\1)
                 (.)(?!\1|\2)
                 (.)(?!\1|\2|\3)
                  .$/x;