Solved

How to extract an IP using "word boundary"

Posted on 2015-02-10
5
104 Views
Last Modified: 2015-02-10
Hi, I have a very simple regex to find IP addresses in this format: 3.123.210.211

\d.\d\d\d.\d\d\d.\d\d\d

When presented with a string that contains something like 135.231.351.209, it will capture 5.231.351.209, but i don't want it to. I only want it to capture the IP's that come in the form x.xxx.xxx.xxx. I had a look at the "word boundary" option (\b) and it seems like it's what I need, but I'm foggy on the usage of it. Could anyone shed some light please?

Thanks
   Shawn
0
Comment
Question by:shawn857
  • 3
  • 2
5 Comments
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 40602186
I could have sworn I'd previously answered a question similar to this, but I can't find it now...  oh well  = )

You can actually match valid IP address ranges with regex. The following will do this:

\b(25[0-5]|2[0-4]\d|1\d\d|\d?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|\d?\d)){3}\b

Open in new window

0
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 40602188
P.S.

On second glance, based on what is in your question, you probably just need to add the word boundary token ( \b ):

\b\d.\d\d\d.\d\d\d.\d\d\d\b

Open in new window

0
 

Author Comment

by:shawn857
ID: 40602208
Thanks Kaufmed... so do I need a "\b" at the start of my regex and another "\b" at the end to do what I want? Doesn't this activate the "word boundary" capabilities at the beginning *and* the end? if I only want to have "word boundary" activated for the beginning, then I would just put a "\b" at the start of my regex? Or do I always have to have a "\b" on the end? I'm still a little confused about its usage.

Thanks
   Shawn
0
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 500 total points
ID: 40602215
You don't have to have it at the end, but without it there is the possibility that you might match something more than you want. For example, if you had the following blurb:

This is a test of a paragraph that has a bunch of octets, like 1.234.567.890.123, but the octets don't represent an IP address.

Then a regex like "\b\d.\d\d\d.\d\d\d.\d\d\d" would match:

1.234.567.890

If you're sure you won't have anything like this in your text, then you don't need the trailing word boundary. It shouldn't hurt having it in there.
0
 

Author Closing Comment

by:shawn857
ID: 40602431
Thanks you Kaufmed, I now have this working perfectly.

Cheers
   Shawn
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
regex replace up to char or end of line 5 71
Using SELECT with Expression.Lambda 13 90
Regular expression that only finds last instance 1 77
PowerShell Regular Expression 2 58
I have been reconstructing a PHP-based application that has grown into a full blown interface system over the last ten years by a developer that has now gone into business for himself building websites. I am not incredibly fond of writing PHP code o…
Do you hate spam? I do, and I am willing to bet you do as well. I often wonder, though, "if people hate spam so much, why do they still post their email addresses on the web?" I'm not talking about a plain-text posting here. I am referring to the fa…
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…

680 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question