lookbehind

In the "Advanced Regular Expresssion" chapter in Mastering Perl , I have a broken example for which I can't figure out a nice fix. The example is perhaps trying to be too clever for its own good, but maybe someone can fix it for me. There could be a free copy of the book in it for working fixes. :) In the section talking about lookarounds, I wanted to use a negative lookbehind to implement a commifying routine for numbers with fractional portions. The point was to use a negative lookbehind because that was the topic. I stupidly did this: $_ = '$1234.5678'; s/(?<!\.\d)(?<=\d)(?=(?:\d\d\d)+\b)/,

I have the following CSS markup. .previous-container{ float:left; } .primary-commands { float:right; } Using the regex syntax search (?<=[\s,;])([a-zA-Z\-]+): it highlights the CSS property name as expected, however, upon clicking replace nothing is replaced. I have tried using group token syntax in replace line e.g. $[nth group] and any plain literal string replacement. No matter my attempts it will not replace the matched string with anything. I am using notepad++ version 6.7.5. Perhaps there is something obvious I am missing here? Based on comments to the original question here are some

I'm trying to retrieve the category part this string " property_id=516&category=featured-properties ", so the result should be "featured-properties", and I came up with a regular expression and tested it on this website http://gskinner.com/RegExr/ , and it worked as expected, but when I added the regular expression to my javascript code, I had a "Invalid regular expression" error, can anyone tell me what is messing up this code? Thanks! var url = "property_id=516&category=featured-properties" var urlRE = url.match('(?<=(category=))[a-z-]+'); alert(urlRE[0]); ajm Positive lookbehinds (your ?<=

Im trying to do something fairly simple with regular expression in python... thats what i thought at least. What i want to do is matching words from a string if its preceded and followed by a whitespace. If its at the beginning of the string there is no whitespace required before - if its at the end, dont't search for whitespace either. Example: "WordA WordB WordC-WordD WordE" I want to match WordA WordB WordE . I only came up with overcomplicated way of doing this... (?<=(?<=^)|(?<=\s))\w+(?=(?=\s)|(?=$)) It seems to me there has to be a simple way for such a simple problem.... I figured i

I have this pattern written ^.*\.(?!jpg$|png$).+$ However there is a problem - this pattern matches file.name.jpg (2 dots) It works correctly (does not match) on filename.jpg. I am trying to figure out how to make it not match ANY .jpg files even if the file's name has 2 or more dots in it. I tried using a look behind but python complains about not using a fixed width (which I'm not exactly sure what that means, but the file name will be variable length.) This should work: ^.*\.(?!jpg$|png$)[^.]+$ Use os.path 's nifty functions to properly split up the filepath into components for easier