On Wed, Nov 18, 2009 at 5:05 PM, Thomas Bätzler <t.baetz...@bringe.com>wrote:
> Hi,
>
> Dermot <paik...@googlemail.com> suggested:
> > 2009/11/17 mangled...@yahoo.com <mangled...@yahoo.com>:
>
> > > Can anyone tell me hoq to write a regular expression which matches
> > > anything _except_ a litteral string ?
> > >
> > > For instance, I want to match any line which does not begin with
> > > Nomatch. So in the following :
>
>
> > You would negate the pattern. Something like this:
> >
> > #!/usr/bin/perl
> >
> >
> > use strict;
> > use warnings;
> >
> > while (<DATA>) {
> > print if ! /^Nomatch/;
> > }
> >
> > __DATA__
> > Line1 xxxx
> > Line2 yyyy
> > Nomatch zzzz
> > Line3 aaaa
> > Line 4 bbbb
>
> One could also use a zero-with negative look-ahead assertion:
>
> #!/usr/bin/perl -w
>
> use strict;
>
> while( my $line = <DATA> ){
> if( $line =~ m/^(?!Nomatch)/ ){
> print "match: $line";
> }
> }
>
> __DATA__
> Line1 xxxx
> Line2 yyyy
> Nomatch zzzz
> Line3 aaaa
> Line 4 bbbb
>
> Cheers,
> Thomas
>
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>
>
Look ahead notation works only on relatively recent versions of Perl, if
your environment contains things like HP-UX that ships with a decades old
version of Perl 5.005 I believe it is (depending on the version of HP-UX of
course) you might get in trouble.
I would therefore not use it or make the script explicitly require 5.6 or
higher just in case.
Regards,
Rob
