On 24/08/2011 15:54, Ramprasad Prasad wrote:
Assume I have to find the first unique character in a string $string = "abtable"; # t is the first unique string I tried using a negative backtrace lookup to get the answer in a single regex ... But something is missing. /(.).(?!\1)/&& print $1; it seems fine ... But doesn't work
Your regex matches any two characters that are not followed by the first of those two characters. So it finds 'ab' and sees that 't' follows, which is not the same as 'a' so a match has been found. You mean to match any single character that is not followed by a string containing itself. Like this use strict; use warnings; my $string = "abtable"; print $1 if $string =~ /(.)(?!.*\1)/; __END__ Output is 't'. HTH, Rob -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
