Say you have an IP address: 74.125.45.100 so its A.B.C.D
Is there a way to use RegEx to get A,B,C separately?
From the above your regex parser should return parameters 1, 2, 3 and 4 which can then be processed separately.
Lazarus
2009-07-07 15:27:28
Note this won't validate an IP address (it'd accept 111111111111.1.000000000000.1234567890) but you didn't ask for that so it's probably okay!
butterchicken
2009-07-07 15:27:49
Each bracketed section '()' returns a value from the regex
Lazarus
2009-07-07 15:28:05
/([012]\d{,2})\.([012]\d{,2})\.([012]\d{,2})\.([012]\d{,2})/ ?
Lazarus
2009-07-07 15:29:27
The question only asked to extract the values, not to validate the syntax. :)
David Dorward
2009-07-07 16:03:17
+5
A:
([0-9]+).([0-9]+).([0-9]+).([0-9]+)
...should do it. It's no validating regex though, allows numbers beyond 255 for each part.
Here's a crazy validating one:
\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b
Credit to last regex goes to RegexBuddy makers.
Skurmedel
2009-07-07 15:26:41
So maybe ([0-9][0-9][0-9]).([0-9][0-9][0-9]).([0-9][0-9][0-9]).([0-9][0-9][0-9])\ :)
amischiefr
2009-07-07 15:28:12
@amischiefr, that would accept 000-999, while the one Skurmedel provided only accepts 000-255, the later being a correctly formatted ip address.
Simon Svensson
2009-07-07 15:56:36
+6
A:
Something very simple yet ugly would work.. giving you four groups one for each octet.
(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})
Quintin Robinson
2009-07-07 15:26:52
+9
A:
If it is just to extract the numbers from the IP and not to validate the IP address then you could just do:
[0-9]
However, I think a simple String.Split(".") would be an easier option.
James
2009-07-07 15:26:55
+1 for suggesting String.Split, because using a regex for this is silly, unless you're trying to *find* an ip address in a longer string.
Brian
2009-07-07 15:33:57
+1 for String.Split, it sounds like a lot healthier solution that building a state machine (which regex is).
Simon Svensson
2009-07-07 15:57:14
It's definately easier, the only caveat would be if the IPs appear at arbitrary positions in a text body.
Skurmedel
2009-07-07 16:05:17
A:
While others have pointed out various good regexps; May I ask why you absolutely must use regular expressions for that? It will be slow and error-prone. Most platforms do have integrated IP address functionality, or provide a way to call to inet_aton.
phihag
2009-07-07 15:42:44
+1
A:
In case someone needs a validating RegEx for (all possible) IPv4 addresses:
([^\d.]|^)([01]{0,1}\d{1,2}|2[0-5][0-5])[.]([01]{0,1}\d{1,2}|2[0-5][0-5])[.]([01]{0,1}\d{1,2}|2[0-5][0-5])[.]([01]{0,1}\d{1,2}|2[0-5][0-5])([^\d]|$)
The IP is contained in 2nd, 3rd and 4th parameters. 1st and last are not used. Those are necessary otherwise a wrong IP like:
999.1.2.3
would be catched as "99.1.2.3". I am not sure if you want to allow IP ending with a dot, e.g.
1.2.3.4.
If not, change the last part to ([^\d.]|$). I do not allow any dots in front of it though.
I still think this RegEx is a messed monster :) and a better solution would be to validate by hand using a function.
Howdy
2009-07-09 13:06:20