Ok, here again.
I'll promise to study deeply the regular expression soon :P
Language: PhP
Problem:
Match if some badword exist inside a string and do something.
The word must be not included inside a "greater word". I mean if i'll search for "rob" (sorry Rob, i'm not thinking you're a badword), the word "problem have to pass without check.
I'd googled around but found nothing good for me. So, I thought something like this:
If i match the word with after and before any character of the following:
.
,
;
:
!
?
(
)
+
-
[whitespace]
I can simulate a check against single word inside a string.
Finally the Questions:
There's a better way to do it?
If not, which will be the correct regexp to consider [all_that_char]word[all_that_char]?
Thanks in advance to anyone would help!
Maybe this is a very stupid question but today is one of that day when move our neurons causes an incredible headache :|
Look up \b (word boundary):
Matches at the position between a word
character (anything matched by \w) and
a non-word character (anything matched
by [^\w] or \W) as well as at the
start and/or end of the string if the
first and/or last characters in the
string are word characters.
(http://www.regular-expressions.info/reference.html)
So: \brob\b matches rob, but not problem.
You can use \b, see Whole word bounderies.
Related
I am looking for a pattern that matches everything until the first occurrence of a specific character, say a ";" - a semicolon.
I wrote this:
/^(.*);/
But it actually matches everything (including the semicolon) until the last occurrence of a semicolon.
You need
/^[^;]*/
The [^;] is a character class, it matches everything but a semicolon.
^ (start of line anchor) is added to the beginning of the regex so only the first match on each line is captured. This may or may not be required, depending on whether possible subsequent matches are desired.
To cite the perlre manpage:
You can specify a character class, by enclosing a list of characters in [] , which will match any character from the list. If the first character after the "[" is "^", the class matches any character not in the list.
This should work in most regex dialects.
Would;
/^(.*?);/
work?
The ? is a lazy operator, so the regex grabs as little as possible before matching the ;.
/^[^;]*/
The [^;] says match anything except a semicolon. The square brackets are a set matching operator, it's essentially, match any character in this set of characters, the ^ at the start makes it an inverse match, so match anything not in this set.
None of the proposed answers did work for me. (e.g. in notepad++)
But
^.*?(?=\;)
did.
Try /[^;]*/
Google regex character classes for details.
sample text:
"this is a test sentence; to prove this regex; that is g;iven below"
If for example we have the sample text above, the regex /(.*?\;)/ will give you everything until the first occurence of semicolon (;), including the semicolon: "this is a test sentence;"
Try /[^;]*/
That's a negating character class.
This was very helpful for me as I was trying to figure out how to match all the characters in an xml tag including attributes. I was running into the "matches everything to the end" problem with:
/<simpleChoice.*>/
but was able to resolve the issue with:
/<simpleChoice[^>]*>/
after reading this post. Thanks all.
this is not a regex solution, but something simple enough for your problem description. Just split your string and get the first item from your array.
$str = "match everything until first ; blah ; blah end ";
$s = explode(";",$str,2);
print $s[0];
output
$ php test.php
match everything until first
This will match up to the first occurrence only in each string and will ignore subsequent occurrences.
/^([^;]*);*/
"/^([^\/]*)\/$/" worked for me, to get only top "folders" from an array like:
a/ <- this
a/b/
c/ <- this
c/d/
/d/e/
f/ <- this
Really kinda sad that no one has given you the correct answer....
In regex, ? makes it non greedy. By default regex will match as much as it can (greedy)
Simply add a ? and it will be non-greedy and match as little as possible!
Good luck, hope that helps.
This works for getting the content from the beginning of a line till the first word,
/^.*?([^\s]+)/gm
I faced a similar problem including all the characters until the first comma after the word entity_id. The solution that worked was this in Bigquery:
SELECT regexp_extract(line_items,r'entity_id*[^,]*')
I am stuck trying to create a regex that will allow for letters, numbers, and the following chars: _ - ! ? . ,
Here is what I have so far:
/^[-\'a-zA-Z0-9_!\?,.\s]+$/ //not escaping the ?
and this version too:
/^[-\'a-zA-Z0-9_!\?,.\s]+$/ //attempting to escape the ?
Neither of these seem to be able to match the following:
"Oh why, oh why is this regex not working! It's getting pretty frustrating? Frustrating - that is to say the least. Hey look, an underscore_ I wonder if it will match this time around?"
Can somebody point out what I am doing wrong? I must point out that my script takes the user input (the paragraph in quotes in this case) and strips all white space so actual input has no white space.
Thanks!
UPDATE:
Thanks to Lix's advice, this is what I have so far:
/^[-\'a-zA-Z0-9_!\?,\.\s]+$/
However, it's still not working??
UPDATE2
Ok, based on input this is what's happening.
User inputs string, then I run the string through following functions:
$comment = preg_replace('/\s+/', '',
htmlspecialchars(strip_tags(trim($user_comment_orig))));
So in the end, user input is just a long string of chars without any spaces. Then that string of chars is run using:
preg_match("#^[-_!?.,a-zA-Z0-9]+$#",$comment)
What could possibly be causing trouble here?
FINAL UPDATE:
Ended up using this regex:
"#[-'A-Z0-9_?!,.]+#i"
Thanks all! lol, ya'll are going to kill me once you find out where my mistake was!
Ok, so I had this piece of code:
if(!preg_match($pattern,$comment) || strlen($comment) < 2 || strlen($comment) > 60){
GEEZ!!! I never bothered to look at the strlen part of the code. Of course it was going to fail every time...I only allowed 60 chars!!!!
When in doubt, it's always safe to escape non alphanumeric characters in a class for matching, so the following is fine:
/^[\-\'a-zA-Z0-9\_\!\?\,\.\s]+$/
When run through a regular expression tester, this finds a match with your target just fine, so I would suggest you may have a problem elsewhere if that doesn't take care of everything.
I assume you're not including the quotes you used around the target when actually trying for a match? Since you didn't build double quote matching in...
Can somebody point out what I am doing wrong? I must point out that my script takes the user input (the paragraph in quotes in this case) and strips all white space so actual input has no white space.
in which case you don't need the \s if it's working correctly.
I got the following code to work as expected to (running php5):
<?php
$pattern = "#[-'A-Z0-9_?!,.\s]+#i";
$string = "Oh why, oh why is this regex not working! It's getting pretty frustrating? Frustrating - that is to say the least. Hey look, an underscore_ I wonder if it will match this time around?";
$results = array();
preg_match($pattern, $string, $results);
echo '<pre>';
print_r($results);
echo '</pre>';
?>
The output from print_r($results) was as following:
Array
(
[0] => Oh why, oh why is this regex not working! It's getting pretty frustrating? Frustrating - that is to say the least. Hey look, an underscore_ I wonder if it will match this time around?
)
Tested on http://writecodeonline.com/php/.
It's not necessary to escape most characters inside []. However, \s will not do what you want inside the expression. You have two options: either manually expand (/^[-\'a-zA-Z0-9_!?,. \t\n\r]+$/) or use alternation (/^(?:[-\'a-zA-Z0-9_!?,.]|\s)+$/).
Note that I left the \ before the ' because I'm assuming you're putting this in a PHP string and I wouldn't want to suggest a syntax error.
The only characters with a special meaning within a character class are:
the dash (since it can be used as a delimiter for ranges), except if it is used at the beginning (since in this case it is no part of any range),
the closing bracket,
the backslash.
In "pure regex parlance", your character class can be written as:
[-_!?.,a-zA-Z0-9\s]
Now, you need to escape whatever needs to be escaped according to your language and how strings are written. Given that this is PHP, you can take the above sample as is. Note that \s is interpreted in character classes as well, so this will match anything which is matched by \s outside of a character class.
While some manuals recommend using escapes for safety, knowing the general regex rules for character classes and applying them leads to shorter and easier to read results ;)
I'm building this regex with a positive look ahead in it. Basically it must select all text in the line up to last period that precedes a ":" and add a "|" to the end to delimit it. Some sample text below. I am testing this in gskinner and editpadpro which has full grep regex support apparently so if I could get the answers in that for I'd appreciate it.
The regex below works to a degree but I am unsure if it is correct. Also it falls down if the text contains brackets.
Finally I would like to add another ignore rule like the one that ignores but includes "Co." in the selection. This second ignore rule would ignore but include periods that have a single Capital letter before them. Sample text below too. Thanks for all the help.
^(?:[^|]+\|){3}(.*?)[^(?:Co)]\.(?=[^:]*?\:)
121| Ryan, T.N. |2001. |I like regex. But does it like me (2) 2: 615-631.
122| O' Toole, H.Y. |2004. |(Note on the regex). Pages 90-91 In: Ryan, A. & Toole, B.L. (Editors) Guide to the regex functionality in php. Timmy, Tommy& Stewie, Quohog. * Produced for Family Guy in Quohog.
I don't think I understand what you want to do. But this part [^(?:Co)] is definitely not correct.
With the square brackets you are creating a character class, because of the ^ it is a negated class. That means at this place you don't want to match one of those characters (?:Co), in other words it will match any other character than "?)(:Co".
Update:
I don't think its possible. How should I distinguish between L. Co. or something similar and the end of the sentence?
But I found another error in your regex. The last part (?=[^:]*?\:) should be (?=[^.]*?\:) if you want to match the last dot before the : with your expression it will match on the first dot.
See it here on Regexr
This seems to do what you want.
(.*\.)(?=[^:]*?:)
It quite simply matches all text up to the last full stop that occurs before the colon.
I'm trying to pull a word out of an email subject line to use as a category for attached email. Preg_match works great as long as it's not just a single word (which is what I'd like to do anyway). If there is only one word in the subject line, I just get an empty array. I've tried to treat $matches as just a variable in that case, but that doesn't work either. Can anyone tell me if preg_match will work on a single word, or what the better way to do this would be?
Thanks very much
Assuming \b(?:word1|word2|word3)\b
The reason it wont match "word1" is because you included a word separator, the \b.
What you can do is just simply always inject the word separator:
preg_match("\b(?:word1|word2|word3)\b", "." . $subject . ".", $matches);
Crude but effective.
preg_match will work on a string one character long. I think that the issue here is probably your regex. My guess is that you're testing for whitespace and because it isn't finding any it says that there is no match. Try appending '^([^\s]*)$|' to your regex and I wager it will start picking up those one word values. ([^\s] means give me anything which has no spaces in it, | means 'or'. By adding it to the front of your regex, it will include things without whitespace or whatever you already had)
I'm trying to find the correct Regular Expression to match all RT scenarios on Twitter (can't wait to Twitter's new retweet API).
The way I see it, RT's can be at the beginning, middle, or end of the string returned from Twitter.
So, I need something at the beginning and end of this Regular Expression:
([Rr])([Tt])
No matter what I try, I cannot match all scenarios in one Regular Expression. I tried
[^|\s+]
to match the scenario where the RT will appear either at the beginning of the string or after one or more whitespace characters, but it didn't work the same for the end of the string or RT. I tried
[\s+|$]
to match a case when the RT appear either in the end of the string or there's one or more whitespace characters following it, same as with the 'pre' -- it didn't work.
Can someone please explain what am I doing wrong here? Any help or suggestions will be highly appreciated (as always :) )
You'll probably be happiest with something like:
/\brt\b/i
Which will find isolated instances of RT (that is, surrounded by word-boundaries), and use the /i modifier at the end of the regex to make it case-insensitive.
You want the word boundaries so that you don't end up thinking random tweets containing words like "Art" and "Quartz" are actually retweets. Even then, it's going to have false positives.
By default, a regular expression can (and will) match anywhere inside a string, so you don't need to account for what may precede or follow your match if indeed you don't care what it is or if it is present.
if(preg_match('/\brt\s*#(\w+)/i', $tweet, $match))
echo 'Somebody retweeted ' . $match[1] . "\n";