On Aug 22, Michel Blanc said:
>Jeff 'japhy/Marillion' Pinyan a écrit :
>>
>
>> I think you mean "if a letter has already matched, it CAN'T repeat again
>> in the string" -- meaning, each character must be unique.
>
>Yes, that's right.
>
>> It's not a simple task without a complex regex assertion, (??{ ... }).
>>
>> I can provide a solution, but I cannot guarantee it will be easy to
>> understand once explained.
>
>I already spend a lot of energy on your JAPHs :)
>Thank you for spending time on this.
>When you'll send me your solution, I'll come back and tell you if I
>understand what you did !
Someone else has already shown the general approach for ensuring a
unique-character string:
sub unique_characters {
$_[0] =~ /(.).*?\1/s ? 0 : 1
}
We can extrapolate upon this idea and test afterward that the string
doesn't contain any unwanted characters:
sub unique_char_set {
my ($str, $chars) = @_;
return 0 if $str =~ /[^\Q$chars\E]/;
return !($str =~ /(.).*?\1/s);
}
This returns false if there is an invalid character, or if there is a
doubled character. Otherwise, it returns true.
You can do this using the (??{ ... }) assertion, like I suggested. It is
more complex, and I'm not sure how it compares speed-wise. And, when I
think of it, it is totally improper.
--
Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/
** Look for "Regular Expressions in Perl" published by Manning, in 2002 **
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