In article <[EMAIL PROTECTED]>, John W. Krahn wrote:
> Kevin Pfeiffer wrote:
>>
>> In article <[EMAIL PROTECTED]>, John W. Krahn wrote:
>>
>> > my $string1 = 'C:\Program files\directory1\directory2\directory3';
>> > my $string2 = 'C:\Program files\directory1\dir2\dir3';
>> >
>> > ( my $nulls = $string1 ^ $string2 ) =~ s/^(\0+).*/$1/s;
>> >
>> > ( my $string3 = substr $string1, 0, length $nulls ) =~ s/[^\\]*$//;
>>
>> Wish I understood how that works...
>
> ^ is the exclusive or (xor) operator. If you xor two different numbers
> you will get a non-zero number and if you xor two identical numbers you
> will get zero. Xor on strings xors each character in the two strings so
> that characters that are the same in both strings will become "\0"
> (ASCII NUL). The substitution removes everything after the leading NULs
> so you are left with a string of NULs the length of which is the number
> of characters at the beginning of the first two strings that are
> identical. In the example above, that puts a string of 31 "\0"
> characters in the variable $nulls.
>
> The 31 character string at the beginning of $string1 (or $string2, it
> doesn't matter which) is assigned to $string3 ('C:\Program
> files\directory1\dir') and any non-'\' character is removed from the end
> so that $string3 finally contains 'C:\Program files\directory1\'.
Thanks!
>> Here's my novice version (but I'm guessing the better/portable way is to
>> use File::Spec?)...
>>
>> my @array1 = split /\\/, $string1;
>> my @array2 = split /\\/, $string2;
>> my @diff;
>
> my $length = @array1 < @array2 ? @array1 : @array2;
I had this in and removed it at the last minute, deciding that it wasn't
necessary (but forgot to change the next line in my already copied-in
version)...
>> for (0 .. $length) {
>> last if ($array1[$_] ne $array2[$_]); # avoid trailing /
>> push @diff, "\\" if @diff;
>> push @diff, $array1[$_];
[...]
--
Kevin Pfeiffer
International University Bremen
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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