my $string = "RYOURPOSTBROKEN";

print("input:     $string\n");
print("expecting: R YOURPOSTBR OK EN\n");
print("\n");

{  #  mwah (split)
   my $re = qr/(?<=[KR])(?!P)/;
   my @arr = split $re, $string;
   print("split $re: @arr\n");
}

{  # tachyon-II (re)
   my $re = qr/(.*?[KR])(?!P)/s;
   my @arr = $string =~ /$re/g;
   print("$re: @arr\n");
}

{  # mwah (re)
   my $re = qr/[^KR]+.(?!P)/s;
   my @arr = $string =~ /$re/g;
   print("$re: @arr\n");
}
[download]

input:     RYOURPOSTBROKEN
expecting: R YOURPOSTBR OK EN

split (?-xism:(?<=[KR])(?!P)): R YOURPOSTBR OK EN
(?s-xim:(.*?[KR])(?!P)): R YOURPOSTBR OK
(?s-xim:[^KR]+.(?!P)): YOU POSTBR OK EN
(?s-xim:[^KR]*.(?!P)): R YOU POSTBR OK EN
[download]

Oh well, I made a mistake (better really test the code next time).

I couldn't come up with a solution dropping the .*?, so Tachyon-II's solution only needs a slight modification ...

...
my @arr = $string =~ / .*? [KR] (?!P)  | [^KR]+$ /gx;
...
[download]

... for getting the strings tail.

Thanks for checking this!

Regards

mwa

That'll learn me ;-) Testing OPs code and not my own! Thanks for fixing it and pointing out you don't need the ( ).

cheers