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Regexp to normalise (pad with zeroes) IP addresses

Answer 1

+1 A:

Spit on ".", pad, join. No regex needed. Regex would not provide any benefit, even.

JavaScript, for example:

var ip = "110.12.23.40";

ip = ip.split(".").map( function(i) {
  return ("00"+i).slice(-3);
}).join(".");

alert(ip);  // 110.012.023.040

Tomalak 2010-07-28 06:22:03

Erm - where in my post or tags does it say I can run jQuery? Or is your post a textpad snippet I do not know about?I am in an editor with 1.5 million lines and need to run a regex.I can do this in JS just fine if I could run JS in my editor.

mplungjan 2010-07-28 07:02:04

@mplungjan: Erm - where in my answer do I say that this code would be jQuery? It says JavaScript, and that's what it is. There are methods to manipulate text files outside of an editor, and I think this is one case where it would be beneficial to do so.

Tomalak 2010-07-28 07:12:50

Thanks for your comment and sorry for the erm - just a little tired of what I see as unrelated answers to my questions at SO so far. I need a regex in my editor. I use JS daily. can also write a JAVA or REXX program that reads through the file and pads the ip addresses. But that is not what I want or need right now.PS: Your "map" is not average JS, but JS 1.6. Very clever and useful in other contexts

mplungjan 2010-07-28 07:47:37

@mplungjan: My JavaScript was to illustrate a point, only. I could have used another language. You cannot easily use regex for this since a) regex *finds*, it does not replace; b) finding the correct spots to insert zeros can be difficult in the context of a huge log file and c) this will always be a multi-step operation, to do it correctly it would require 8 search-and-replace steps (4 bytes separatetly, "0" and "00" prefixes separately). What I'm saying is this: Use a programming language to process your text file. Regex-find IPs, replace using something equivalent to my code.

Tomalak 2010-07-28 07:58:21

I see what you are saying, but as I mentioned, I can replace captured strings. If the captured input is [0-9]{1} my replace is 00\1 if [0-9]{2} it is 0\1 and if [0-9]{3} it is \1Since I can do it one at a time, I was sure someone could come up with a compound regex like this single replace ([0-9]{1})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3}) -> 00\1.\2.\3.\4So I guess I can do it in 4 regex now.

mplungjan 2010-07-28 08:20:39

more than 4 actually

mplungjan 2010-07-28 08:27:45

@mplungjan: Yes, eight, as I said. You need to capture and replace these cases separately: `"x.*.*.*"`, `"xx.*.*.*"`, `"*.x.*.*"`, `"*.xx.*.*"`, `"*.*.x.*"`, `"*.*.xx.*"`, `"*.*.*.x"`, `"*.*.*.xx"`. Not replacing complete IP-address-like structures will leave you with leading zeros in dates, times and other data. It's not impossible to do in a text editor, but a lot more hassle than it's worth. (And as far as efficiency goes: This way you would need to go over the entire file eight times - but with a small helper program only once.)

Tomalak 2010-07-28 08:36:07

It was actually not a huge thing, 8 times enter and I had the ^ making sure it was only the first part of the line.It took less than what I spent on this question ;) Also I had to sort and remove crap requests something textpad is very good helping your eyes with and programming languages not...Thanks for your input - At least I learned about map()

mplungjan 2010-07-28 11:30:00

Answer 2

+1 A:

Ok, I decided to do it in more than one go. I post it here for future reference or in case someone comes up with a single regex

Note there is a trailing space on each find and each replace

^([0-9]{1})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3}) -> 00\1.\2.\3.\4 
^([0-9]{2})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3}) -> 0\1.\2.\3.\4 

^([0-9]{3})\.([0-9]{1})\.([0-9]{1,3})\.([0-9]{1,3}) -> \1.00\2.\3.\4 
^([0-9]{3})\.([0-9]{2})\.([0-9]{1,3})\.([0-9]{1,3}) -> \1.0\2.\3.\4 

^([0-9]{3})\.([0-9]{3})\.([0-9]{1})\.([0-9]{1,3}) -> \1.\2.00\3.\4 
^([0-9]{3})\.([0-9]{3})\.([0-9]{2})\.([0-9]{1,3}) -> \1.\2.0\3.\4 

^([0-9]{3})\.([0-9]{3})\.([0-9]{3})\.([0-9]{1}) -> \1.\2.\3.00\4 
^([0-9]{3})\.([0-9]{3})\.([0-9]{3})\.([0-9]{2}) -> \1.\2.\3.0\4

Textpad syntax:

^\([0-9]\{1\}\)\.\([0-9]\{1,3\}\)\.\([0-9]\{1,3\}\)\.\([0-9]\{1,3\}\) -> 00\1.\2.\3.\4 
^\([0-9]\{2\}\)\.\([0-9]\{1,3\}\)\.\([0-9]\{1,3\}\)\.\([0-9]\{1,3\}\) -> 0\1.\2.\3.\4 

^\([0-9]\{3\}\)\.\([0-9]\{1\}\)\.\([0-9]\{1,3\}\)\.\([0-9]\{1,3\}\) -> \1.00\2.\3.\4 
^\([0-9]\{3\}\)\.\([0-9]\{2\}\)\.\([0-9]\{1,3\}\)\.\([0-9]\{1,3\}\) -> \1.0\2.\3.\4 

^\([0-9]\{3\}\)\.\([0-9]\{3\}\)\.\([0-9]\{1\}\)\.\([0-9]\{1,3\}\) -> \1.\2.00\3.\4 
^\([0-9]\{3\}\)\.\([0-9]\{3\}\)\.\([0-9]\{2\}\)\.\([0-9]\{1,3\}\) -> \1.\2.0\3.\4 

^\([0-9]\{3\}\)\.\([0-9]\{3\}\)\.\([0-9]\{3\}\)\.\([0-9]\{1\}\) -> \1.\2.\3.00\4 
^\([0-9]\{3\}\)\.\([0-9]\{3\}\)\.\([0-9]\{3\}\)\.\([0-9]\{2\}\) -> \1.\2.\3.0\4

mplungjan 2010-07-28 08:36:27

Why are you escaping all parentheses and curly braces? Is this textpad thing?

Kobi 2010-07-28 08:40:44

"in case someone comes up with a single regex" -> Nobody will, because this is impossible. And yes, I use that word rarely and if at all, then without exaggeration.

Tomalak 2010-07-28 08:59:17

@Kobi: Agreed, the backslashes should be removed. They have nothing to do with the shown regexes.

Tomalak 2010-07-28 09:00:21

Yes it is a textpad thing.

mplungjan 2010-07-28 09:09:13

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Regexp to normalise (pad with zeroes) IP addresses

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