Regular expressions question

Hi,

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 :

Line1 xxxx
Line2 yyyy
Nomatch zzzz
Line3 aaaa
Line 4 bbbb

I would match every line except the one containing "Nomatch zzzz"

Many thanks,

David

2009/11/17 mangled_us@yahoo.com <mangled_us@yahoo.com>:

Hello,




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
~

Output:
Line1 xxxx
Line2 yyyy
Line3 aaaa
Line 4 bbbb

see
perldoc perlop #Logical-Not
and
perldoc perlsyn
and of course
perldoc perlrequick


HTH,
Dp.

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On Wed, Nov 18, 2009 at 5:05 PM, Thomas B=C3=A4tzler <t.baetzler@bringe.com=

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

--000e0cdfcdd6b1f82e0478a78389--

Hi,

Dermot <paikkos@googlemail.com> suggested:




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