Are there any tools out there that will build a generic regular expression for me if it's given a specific string as input?
At the moment I"ll settle for an actual regex instead of a tool.
Note that in my case I can use HOST in angle brackets to represent the IP address in the regex. My goal is to build a regex for the tool called "fail2ban".
Lets say my string is
[2012-11-06 22:52:40] NOTICE[4339] chan_sip.c: Registration from '"202"' failed for '111.111.11.1:9546' - Wrong password
(It looks like this forum is apparently stripping out symbols and/or otherwise messing with my string so I'll use the following conventions so you can see what it's supposed to say:
DQ to represent a DOUBLE QUOTE "
LAB to represent a LEFT ANGLE BRACKET <
RAB to represent a RIGHT ANGLE BRACKET >
AT to represent an at sign #
)
Using the above conventions:
[2012-11-06 22:52:40] NOTICE[4339] chan_sip.c: Registration from 'DQ 202 DQ LAB sip:202 AT emailAddress RAB' failed for '111.111.11.1:9546' - Wrong password
Note that I have added spaces between symbols to increase readability. They are not part of the original string.
I have tried NOTICE.* .: Registration from '.' failed for ':.*' - Wrong password
and:
NOTICE.* .: Registration from '\".\"' failed for ':.*' - Wrong password
What is the proper regex please?
Thank you in advance
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sidenote: If none already exist, it sure would be nice if someone could build a tool to automate building a regular expression given a particular string.
Here's what I'm thinking.
The string could be easily parsed by the following C library functions isalphanum(c), isalpha(c), isdigit(c), ispunct(c), isspace(c).
The hard part is building a regular expression generator.
Try
NOTICE.+: Registration from '.+' failed for '.+' - Wrong password
The tool I used to flesh that out was RegExr.
EDIT:
I Googled for "regex generator" and came across this result. That is probably what you are looking for (self: adds link to bookmarks)
Related
In using the Page Object gem, I'm trying to pull text from a page to verify error messages. One of these error messages contains double-quotes, but when the page object pulls the text from the page, it pulls some other characters.
expected ["Please select a category other than the Default â?oEMSâ?? before saving."]
to include "Please select a category other than the Default \"EMS\" before saving."
(RSpec::Expectations::ExpectationNotMetError)
I'm not quite sure how to escape these - I'm not sure where I could use Regexs and be able to escape these odd characters.
Honestly you are over complicating your validation.
I would recommend simplifying what you are trying to do, start by asking yourself: Is the part in quotes a critical part of your validation?
If it is, isolate it by doing a String.contains("EMS")
If it is not, then you are probably doing too much work, only check for exactly what you need in validation:
String.beginsWith("Please select a category other than the Default")
With respect to the actual issue you are having, on a technical level you have an encoding issue. Encode your result string with utf-8 before you pass it to your validation and you will be fine.
Good luck
It's pretty likely that somewhere along the line encoded the string improperly. (A tipoff is the accented characters followed by ?.) It seems pretty likely that the quotes were converted to "smart quotes" somewhere. This table compares Window-1252 to UTF-8:
Code Point Characters UTF-8 Bytes
Unicode Windows
1252 Expected Actual
------ ---- - --- -----------
U+201C 0x93 “ “ %E2 %80 %9C
U+201D 0x94 ” †%E2 %80 %9D
What you'll want to do is spot check various places in the code to find the first place the string is encoded in something other than UTF-8:
puts error_str.encoding
(For clarity, error_str is the variable that holds the string you are testing. I'm using puts, but you might want have another way to log diagnostic messages.)
Once you find the string that's not encoded UTF-8, you can convert it:
error_str.encode('UTF-8')
Or, if the string is hardcoded somewhere, just replace the string.
For more debugging advice, see: 3 Steps to Fix Encoding Problems in Ruby and How to Get From They’re to They’re.
I am trying to grasp the concept of Regular Expressions but seem to be missing something.
I want to ensure that someone enters a string that ends with .wav in a field. Should be a pretty simple Regular Expression.
I've tried this...
[RegularExpression(#"$.wav")]
but seem to be incorrect. Any help is appreciated. Thanks!
$ is the anchor for the end of the string, so $.wav doesn't make any sense. You can't have any characters after the end of the string. Also, . has a special meaning for regex (it just means 'any character') so you need to escape it.
Try writing
\.wav$
If that doesn't work, try
.*\.wav$
(It depends on if the RegularExpression attribute wants to match the whole string, or just a part of it. .* means 'any character, 0 or more times')
Another thing you should consider is what to do with extra whitespace in the field. Users have a terrible habit of adding extra white space in inputs - its why various .Trim() functions are so important. Here, RegularExpressionAttribute might be evaluated before you can trim the input, so you might want to write this:
.*\.wav[\s]*$
The [\s]* section means 'any whitespace character (tabs, space, linebreak, etc) 0 or more times'.
You should read a tutorial on regex. It's not so hard to understand for simple problems like this. When I was learning I found this site pretty handy: http://www.regular-expressions.info/
Has anyone in this forum attempted to solve the ACM programming problem http://acm.mipt.ru/judge/problems.pl?browse=yes&problem=024? It is one of the simpler problems in ACM MIPT and the goal is to evaluate an expression consisting of +, -, * and parentheses. Despite the apparent simplicity, I haven't been able to get my solution accepted, apparently because one of the test case expressions has an operator not stated in the problem. I even added support for division ('/') but that too didn't help. Any idea on what other operator needs to be supported? FYI, my program removes all whitespaces from the input before processing so that spaces shouldn't be a problem. Anything not stated in the problem but needs to be taken care of?
You're being bitten by ruby's handling of strings and characters.
curr_ch = #input[i]
gives you an integer, for the input you get, the ASCII code of the character at index i of the input.
curr_ch == '('
for example compares that integer to the string "(", of course that fails. Also the regex matches fail because you pass them an integer where a string is expected.
Replacing all occurrences of some_var = #input[some_index] with some_var = #input[some_index...some_index+1] gives me a programme that seems to work (it works on a few test inputs I gave it). Probably someone who actually knows the quirks of ruby can give you a better fix.
I'm having a problem getting my RegEx to work with my Ruby script.
Here is what I'm trying to match:
http://my.test.website.com/{GUID}/{GUID}/
Here is the RegEx that I've tested and should be matching the string as shown above:
/([-a-zA-Z0-9#:%_\+.~#?&\/\/=]{2,256}\.[a-z]{2,4}\b(\/[-a-zA-Z0-9#:%_\+.~#?&\/\/=]*)([\/\/[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\/\/[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\/\/])*?\/)/
3 capturing groups:
group 1: ([-a-zA-Z0-9#:%_\+.~#?&\/\/=]{2,256}\.[a-z]{2,4}\b(\/[-a-zA-Z0-9#:%_\+.~#?&\/\/=]*)([\/\/[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\/\/[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\/\/])*?\/)
group 2: (\/[-a-zA-Z0-9#:%_\+.~#?&\/\/=]*)
group 3: ([\/\/[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\/\/[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\/\/])
Ruby is giving me an error when trying to validate a match against this regex:
empty range in char class: (My RegEx goes here) (SyntaxError)
I appreciate any thoughts or suggestions on this.
You could simplify things a bit by using URI to deal parsing the URL, \h in the regex, and scan to pull out the GUIDs:
uri = URI.parse(your_url)
path = uri.path
guids = path.scan(/\h{8}-\h{4}-\h{4}-\h{4}-\h{12}/)
If you need any of the non-path components of the URL the you can easily pull them out of uri.
You might need to tighten things up a bit depending on your data or it might be sufficient to check that guids has two elements.
You have several errors in your RegEx. I am very sleepy now, so I'll just give you a hint instead of a solution:
...[\/\/[0-9a-fA-F]....
the first [ does not belong there. Also, having \/\/ inside [] is unnecessary - you only need each character once inside []. Also,
...[-a-zA-Z0-9#:%_\+.~#?&\/\/=]{2,256}...
is greedy, and includes a period - indeed, includes all chars (AFAICS) that can come after it, effectively swallowing the whole string (when you get rid of other bugs). Consider {2,256}? instead.
can any body tell me how to use regex for negation of string?
I wanna find all line that start with public class and then any thing except first,second and finally any thing else.
for example in the result i expect to see public class base but not public class myfirst:base
can any body help me please??
Use a negative lookahead:
public\s+class\s+(?!first|second).+
If Peter is correct and you're using Visual Studio's Find feature, this should work:
^:b*public:b+class:b+~(first|second):i.*$
:b matches a space or tab
~(...) is how VS does a negative lookahead
:i matches a C/C++ identifier
The rest is standard regex syntax:
^ for beginning of line
$ for end of line
. for any character
* for zero or more
+ for one or more
| for alternation
Both the other two answers come close, but probably fail for different reasons.
public\s+class\s+(?:(?!first|second).)+
Note how there is a (non-capturing) group around the negative lookahead, to ensure it applies to more than just the first position.
And that group is less restrictive - since . excludes newline, it's using that instead of \S, and the $ is not necessary - this will exclude the specified words and match others.
No slashes wrapping the expression since those aren't required in everything and may confuse people that have only encountered string-based regex use.
If this still fails, post the exact content that is wrongly matched or missed, and what language/ide you are using.
Update:
Turns out you're using Visual Studio, which has it's own special regex implementation, for some unfathomable reason. So, you'll be wanting to try this instead:
public:b+class:b+~(first|second)+$
I have no way of testing that - if it doesn't work, try dropping the $, but otherwise you'll have to find a VS user. Or better still, the VS engineer(s) responsible for this stupid non-standard regex.
Here is something that should work for you
/public\sclass\s(?:[^fs\s]+|(?!first|second)\S)+(?=\s|$)/
The second look a head could be changed to a $(end of line) or another anchor that works for your particular use case, like maybe a '{'
Edit: Try changing the last part to:
(?=\s|$)