Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things
 
PerlMonks  

Re^3: regex: negative lookahead

by kennethk (Monsignor)
on Dec 05, 2011 at 16:38 UTC ( #941894=note: print w/ replies, xml ) Need Help??


in reply to Re^2: regex: negative lookahead
in thread regex: negative lookahead

The difference is a lookahead versus a lookbehind. If you ignore the lookahead/lookbehind because they are zero width (don't consume characters), you would expect /^($start(\w+(,\s)?)+)$/ to grab an entire string between start and finish. When you get to the part of the regular expression where you have your assertion, the cursor is here:

log4j.rootLogger=INFO, FILE, SYSLOG ^
If you look ahead of this position, there is nothing, which clearly passes the negative lookahead check. The offending string is behind your position, thus you need a negative lookbehind.


Comment on Re^3: regex: negative lookahead
Select or Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://941894]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others surveying the Monastery: (7)
As of 2014-08-23 03:13 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The best computer themed movie is:











    Results (171 votes), past polls