So building something like this in 1 regex:
"zzz <> ttt> ab" - matches
"z ab <tt> xx" - matches
"zzz ab <>ab> tt" - doesn't match
"ab <a x> <ab>" - doesn't match
That took me a while to work out but it can be done:
#!/usr/local/bin/perl
use strict;
use warnings;
my @data;
$data[0] = "zzz <> ttt> ab";
$data[1] = "z ab <tt> xx";
$data[2] = "zzz ab <>ab> tt";
$data[3] = "ab <a x> <ab>";
foreach my $line ( @data ) {
if ( $line !~ m#(?(?=<.*?ab.*?>)((?<!<).*?ab.*?(?!>))|0)# ) {
print $line . "\n";
}
}
To explain it a little:
(? #if
(?=<.*?ab.*?>) #matches then match
((.*?>)((?<!<).*?ab.*?(?!>)) #else there is no match
|0)
This will match the two lines you do not want so we use != to match the
other two. I am sure you could also put this into a positive formusing =~
but I couldn't be arsed with my manager looking over my sholder wondering
why his report isn't finished :-)
Regards,
Rob
On Mon, Jul 21, 2008 at 12:36 PM, Octavian Rasnita <[EMAIL PROTECTED]>
wrote:
> From: "Rob Coops" <[EMAIL PROTECTED]>
> > You could simply say this:
> > if ( ! m/ab/ ) {
> > #make the world go round
> > }
> > Or assuming you are looping thru a list you could say something like:
> > foreach my $item ( @list ) {
> > next if ( $item =~ m/ab/ );
> > #make the world go round
> > }
>
> I also had this problem some time ago but I couldn't find a solution for
> it.
> I wanted to test something like:
>
> Match only if the string contains somewhere a "ab" in it but it doesn't
> contain "ab" between < and >.
>
> For example:
>
> "zzz <> ttt> ab" - matches
> "z ab <tt> xx" - matches
> "zzz ab <>ab> tt" - doesn't match
> "ab <a x> <ab>" - doesn't match
>
> I've done it by using 2 regular expressions, but I was searching for a
> solution for doing using only a single regular expression.
> Is it possible to test the existence of a string and the non-existence of
> another string using a single regular expression?
>
> I've tried using (?=...) and (?!...) but these 2 expressions can be used
> only if I know where in the string I want a certain string to appear or not
> to appear.
>
> Octavian
>
>
