lookahead

Just a simple regex I don't know how to write. The regex has to make sure a string matches all 3 words. I see how to make it match any of the 3: /advancedbrain|com_ixxocart|p\=completed/ but I need to make sure that all 3 words are present in the string. Here are the words advancebrain com_ixxocart p=completed Use lookahead assertions : ^(?=.*advancebrain)(?=.*com_ixxochart)(?=.*p=completed) will match if all three terms are present. You might want to add \b work boundaries around your search terms to ensure that they are matched as complete words and not substrings of other words (like

Task: - given: a list of images filenames - todo: create a new list with filenames not containing the word "thumb" - i.e. only target the non-thumbnail images (with PIL - Python Imaging Library). I've tried r".*(?!thumb).*" but it failed. I've found the solution (here on stackoverflow) to prepend a ^ to the regex and to put the .* into the negative lookahead: r"^(?!.*thumb).*" and this now works. The thing is, I would like to understand why my first solution did not work but I don't. Since regexes are complicated enough, I would really like to understand them. What I do understand is that the

Is it possible to do string negation in regular expressions? I need to match all strings that do not contain the string ".." . I know you can use ^[^\.]*$ to match all strings that do not contain "." but I need to match more than one character. I know I could simply match a string containing ".." and then negate the return value of the match to achieve the same result but I just wondered if it was possible. You can use negative lookaheads: ^(?!.*\.\.).*$ That causes the expression to not match if it can find a sequence of two periods anywhere in the string. ^(?:(?!\.\.).)*$ will only match if

I'm using the Asp.net change password control in my application and all seems to be find and dandy until a user tells me she has a problem meeting the strength requirements when changing her password. Looking into this, she is using IE 7 and no matter what she puts in, the validation fails (and ONLY in IE 7. Firefox, IE 8, Chrome etc. all work as expected). Here is the regex i'm using: ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*\s).{5,15}$ I've tried out a few others that I've found throughout this site and others that folks seem to be using with no issues and I come across the same problem. It seems

I'm trying re.split to get BCF#, BTS# and LAC, CI from logfile with the header and regular structure inside: ================================================================================== RADIO NETWORK CONFIGURATION IN BSC: E P B F T R C D-CHANNEL BUSY AD OP R ET- BCCH/CBCH/ R E S O&M LINK HR FR LAC CI HOP ST STATE FREQ T PCM ERACH X F U NAME ST /GP ===================== == ====== ==== == ==== =========== = = == ===== == === === BCF-0010 FLEXI MULTI U WO 2 LM10 WO 10090 31335 BTS-0010 U WO 0 0 KHAKHAATT070D BB/- 7 TRX-001 U WO 779 0 1348 MBCCH+CBCH P 0 TRX-002 U WO 659 0 1348 1 TRX-003 U

Since I started writing this question, I think I figured out the answers to every question I had, but I thought I'd post anyway, as it might be useful to others and more clarification might be helpful. I was trying to use a regular expression with lookahead with the javascript function split. For some reason it was not splitting the string even though it finds a match when I call match. I originally thought the problem was from using lookahead in my regular expression. Here is a simplified example: Doesn't work: "aaaaBaaaa".split("(?=B)."); Works: "aaaaBaaaa".match("(?=B)."); It appears the