Re^2: Match zero times in regex

Lookbehind was by first thought, but it doesn't work unless one changes what is currently allowed.

from: 'permit ip host 10.11.1.1 192.168.100.0 0.0.0.255'
IP pair: '192.168.100.0' '0.0.0.255'
from: 'permit ip host  10.11.1.1 192.168.100.0 0.0.0.255'
IP pair: '10.11.1.1' '192.168.100.0'
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Comment on Re^2: Match zero times in regex Download Code

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Re^3: Match zero times in regex by AnomalousMonk (Archbishop) on Dec 13, 2011 at 05:02 UTC
From the OP: ... if the entry is `permit ip``host 10.11.1.1` `192.168.100.0 0.0.0.255` I want to pull out `192.168.100.0 0.0.0.255` but if the entry is `permit ip``10.11.1.0` `0.0.0.255 192.168.100.0 0.0.0.255` I want to pull out `10.11.1.0` `0.0.0.255` `192.168.100.0 0.0.0.255` I don't see how an IP (10.11.1.1 in the example) after 'host' is ever desired to be captured. Am I missing something (wouldn't be the first time)?	[reply] [d/l] [select]
Re^4: Match zero times in regex by ikegami (Patriarch) on Dec 17, 2011 at 09:20 UTC
I don't see how an IP (10.11.1.1 in the example) after 'host' is ever desired to be captured. Exactly, yet I showed that your code does capture it.	[reply]
Re^5: Match zero times in regex by AnomalousMonk (Archbishop) on Dec 17, 2011 at 21:13 UTC
Am I missing something ...? I went back and tried the exact strings of your counter-example (at first, I thought you were (mis-)quoting something, but couldn't figure out what it was) and I finally see your point: if there are two or more whitespaces between 'host' and the immediately following IP, then that IP will not be excluded because there is a position in the string that is followed by one or more whitespaces and is preceded by something that is not 'host', i.e., by one or more whitespaces. OK, got it at last!	[reply]