Re^3: Regex to match ascending sequence

[Laurent_R]

$c //= $d;

is just syntactic sugar for various constructs such as:

$c = defined $c ? $c : $d;

or

$c = $d unless defined $c;

Update: I've just quickly tried on an old VMS platform with Perl 5.8.6 with this regex definition:

 $regex = qr# (\d) (??{ my $c = $1 unless defined $c; ++$c })+ #x;

it still does not seem to work.