Regex matching multiple negative lookahead

问题:

I'm trying to match a string (using a Perl regex) only if it doesn't start with "abc:" or "defg:", but I can't seem to find out how. I've tried something like

^(?:(?!abc:)|(?!defg:))

回答1:

Lookahead (?=foo), (?!foo) and lookbehind (?<=), (?<!) do not consume any characters.

You can:

^(?!abc:)(?!defg:).*

or

^(?!defg:)(?!abc:).*

The order does not make a difference.

回答2:

Try doing this :

^(?!(?:abc|defg):)

回答3:

… or could have dropped the alternation from the original expression:

^(?:(?!abc:)(?!defg:))

回答4:

This will do the task :

^(?!(defg|abc):).*

回答5:

^(?:(?!abc:|defg:).)*$

Try this.See demo.

http://regex101.com/r/hQ9xT1/18

回答6:

Could you please try this:

use strict;
use warnings;
use Cwd;

while(<DATA>)
{
    my $line=$_;
    print $line unless($line=~m/^(abc|defg*)/m);
}

__DATA__
ebc this is testing ebc
dbc this is testing dbc
defg this is testing defg
abc this is testing abc
defg this is testing defg

回答7:

^(?!abc:|defg:)\s*\w+

use this regex. this will avoid line start with "abc:" and "defg:" as you want.