I am trying to find a php preg_match that can match
test1 test2[...] but not test1 test2 [...]
and return test2(...) as the output as $match.
I tried
preg_match('/^[a-zA-Z0-9][\[](.*)[\]]$/i',"test1 test2[...]", $matches);
But it matches both cases and return the full sentence.
Any help appreciated.
preg_match('/([a-zA-Z0-9]+[\[][^\]]+[\]])$/i',"test1 test2[...]", $matches);
notice the + after [a-zA-Z0-9] it says one or more alpha numeric character
the ( and ) around the whole expression would permit you to catch the whole expression.
Since your content is around [] I have changed .* to [^\]] since the regular expression are greedy in case of test2[.....] test3[sadsdasdasdad] it would capture until the end since there is a ].
Also please note since you are using the $ it will match always things in the end, I am not really sure if it's what you intend to do.
You can see this for reference.
Related
I'm writing a simple quiz engine in PHP and supply the question text in this format
question|correct/feedback|wrong/feedback|wrong/feedback
There can be as many wrong/feedback options as necessary. I want to use preg_match to return the results so I can display them. For instance:
q|aaa/aaa|bbb/bbb|ccc/ccc
...should return...
array(
0 => q|aaa/aaa|bbb/bbb|ccc/ccc
1 => q
2 => aaa/aaa
3 => bbb/bbb
4 => ccc/ccc
)
So, far I've got this regular expression which matches the question and the correct/feedback combination...
([^\|]+)\|([^\/]+\/[^\|$]+)
...but I have no idea how to match the remaining wrong/feedback strings
You can also use the "glue" feature in your pattern with preg_match_all, this way it's possible to check if the syntax is correct and to extract each part at the same time.
The glue feature ensures that each match follows immediately the previous match without gap. To do that I use the A global modifier (Anchored to the start of the string or the next position after the previous match).
$s = 'q|aaa/aaa|bbb/bbb|ccc/ccc';
$pat = '~ (?!\A) \| \K [^|/]+ / [^|/]+ (?: \z (*:END) )? | \A [^|/]+ ~Ax';
if ( preg_match_all($pat, $s, $m) && isset($m['MARK']) ) {
$result = $m[0];
print_r($result);
}
I use also a marker (*:END) to be sure that the end of the string is well reached despite of the pattern constraints. If this marker exists in the matches array, it's a proof that the syntax is correct. Advantage: you have to parse the string only once (you don't even need to check the whole string syntax in a lookahead assertion anchored at the start of the string).
demo
If you want the whole question as first item in the result array, just write:
$result = array_merge([$s], $m[0]);
So, after the advice, I've decided to use preg_match to check the syntax and then explode to split the string.
This regex seems to match the string format up until any mismatch occurs.
^[^\|/]+(?:\|[^\|/]+/[^\|/]+)+
If I check that the length of the match is the same as the original string I think this will tell me the syntax is correct. Does this sound feasible?
My PHP version is PHP 7.2.24-0ubuntu0.18.04.7 (cli). However it looks like this problem occurs with all versions I've tested.
I've encountered a very weird bug when using preg_match. Anyone know a fix?
The first section of code here works, the second one doesn't. But the regex itself is valid. For some reason the something_happened word is causing it to fail.
$one = ' (branch|leaf)';
echo "ONE:\n";
preg_match('/(?:\( ?)?((?:(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+(?: ?\| ?(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+)(?: ?\))?/', $one, $matches, PREG_OFFSET_CAPTURE);
print_r($matches); // this works
$two = 'something_happened (branch|leaf)';
echo "\nTWO:\n";
preg_match('/(?:\( ?)?((?:(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+(?: ?\| ?(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+)(?: ?\))?/', $two, $matches2, PREG_OFFSET_CAPTURE);
print_r($matches2); // this doesn't work
It seems somehow related to the word something_happened. If I change this word it works.
The regex is matching 2 or more type names separated by | that may or may not be surrounded in (), and each type name may or may not be preceded by any number of [] (or [some number] or [!some number]) and *.
Try it and see for yourself! Please let me know if you know how to fix it!
The problem lies in the (?:(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+ group: the + quantifier quantifies a group with many subsequent optional patterns, and that creates too many options to match a string before the subsequent patterns.
In PHP, you can workaround the problem by using either
Possessive quantifier:
'/(?:\(\ ?)?((?:(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)++(?:\ ?\|\ ?(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+)(?:\ ?\))?/'
Note the ++ at the end of the group mentioned.
2. Atomic group:
'/(?:\(\ ?)?((?>(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+(?:\ ?\|\ ?(?:\**\[(?:!?\d+)?\])*\**[A-Za-z_]\w*)+)(?:\ ?\))?/'
See this regex demo. Note the (?>...) syntax.
Also, note how the regex is formatted here, it is very convenient to use the x (extended) flag to break the regex into several lines, format it, so that it could be easier to track down the issue. It is required to escape all literal whitespace and # chars, but it is a minor inconvenience when it comes to debugging long patterns like this.
I want to implement non greedy match using .*? pattern. However, I came across one sample string which shows, that non greedy match does not work. This is the code and the sample string:
preg_match_all('/\<w:t.*?\>\<w:p\>/', '<w:t xml:space="preserve"></w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t xml:space="preserve">Text 1 </w:t></w:r><w:r><w:rPr><w:b/><w:u w:val="single"/><w:color w:val="ff0000"/></w:rPr><w:t xml:space="preserve"></w:t></w:r><w:r><w:rPr><w:b/><w:u w:val="single"/><w:color w:val="ff0000"/><w:i/></w:rPr><w:t xml:space="preserve">Text 2</w:t></w:r><w:r><w:t xml:space="preserve"></w:t></w:r><w:r><w:t xml:space="preserve"></w:t></w:r><w:r><w:t xml:space="preserve"></w:t></w:r></w:p></w:t></w:r></w:p><w:p w:rsidRDefault="004D3323" w:rsidP="003F03B1"><w:r><w:t><w:p>', $match);
But if I print_r the $match variable, I see that this pattern matches the whole string. However, what I want is to match only such strings as:
"<w:t><w:p>" and "<w:t any text may go here><w:p>"
So, what I did wrong and how can I fix it? Thanks!
Use this regex instead:
<w:t[^>]*><w:p>
[^>]* allows all characters except >
see https://regex101.com/r/nuMzTk/1
I've got some issues understanding this regex.
I tried doing a pattern but does not work like intended.
What I want is [A-Za-z]{2,3}[0-9]{2,30}
That is 2-3 letters in the beginning and 2-30 numbers after that
FA1321321
BFA18098097
I want to use it to validate an input field but can't figure out how the regex should look like.
Can any one that can help me out even explain a bit about it?
Your regex is correct - just make sure to surround it with / in PHP, and perhaps ^, $ if you want it to strictly match the entire string (no extra characters before/after).
$pattern = "/^[A-Za-z]{2,3}[0-9]{2,30}$/"
$found = preg_match($pattern, $your_str);
From the PHP documentation:
preg_match() returns 1 if the pattern matches given subject, 0 if it does not, or FALSE if an error occurred.
I found a regex pattern for PHP that does the exact OPPOSITE of what I'm needing, and I'm wondering how I can reverse it?
Let's say I have the following text: Item_154 ($12)
This pattern /\((.*?)\)/ gets what's inside the parenthesis, but I need to get "Item_154" and cut out what's in parenthesis and the space before the parenthesis.
Anybody know how I can do that?
Regex is above my head apparently...
/^([^( ]*)/
Match everything from the start of the string until the first space or (.
If the item you need to match can have spaces in it, and you only want to get rid of whitespace immediately before the parenthetical, then you can use this instead:
/^([^(]*?)\s*\(/
The following will match anything that looks like text (...) but returns just the text part in the match.
\w+(?=\s*\([^)]*\))
Explanation:
The \w includes alphanumeric and underscore, with + saying match one or more.
The (?= ) group is positive lookahead, saying "confirm this exists but don't match it".
Then we have \s for whitespace, and * saying zero or more.
The \( and \) matches literal ( and ) characters (since its normally a special chat).
The [^)] is anything non-) character, and again * is zero or more.
Hopefully all makes sense?
/(.*)\(.*\)/
What is not in () will now be your 1st match :)
One site that really helped me was http://gskinner.com/RegExr/
It'll let you build a regex and then paste in some sample targets/text to test it against, highlighting matches. All of the possible regex components are listed on the right with (essentially) a tooltip describing the function.
<?php
$string = 'Item_154 ($12)';
$pattern = '/(.*)\(.*?\)/';
preg_match($pattern, $string, $matches);
var_dump($matches[1]);
?>
Should get you Item_154
The following regex works for your string as a replacement if that helps? :-
\s*\(.*?\)
Here's an explanation of what's it doing...
Whitespace, any number of repetitions - \s*
Literal - \(
Any character, any number of repetitions, as few as possible - .*?
Literal - \)
I've found Expresso (http://www.ultrapico.com/) is the best way of learning/working out regular expressions.
HTH
Here is a one-shot to do the whole thing
$text = 'Item_154 ($12)';
$text = preg_replace('/([^\s]*)\s(\()[^)]*(\))/', $1$2$3, $text);
var_dump($text);
//Outputs: Item_154()
Keep in mind that using any PCRE functions involves a fair amount of overhead, so if you are using something like this in a long loop and the text is simple, you could probably do something like this with substr/strpos and then concat the parens on to the end since you know that they should be empty anyway.
That said, if you are looking to learn REGEXs and be productive with them, I would suggest checking out: http://rexv.org
I've found the PCRE tool there to very useful, though it can be quirky in certain ways. In particular, any examples that you work with there should only use single quotes if possible, as it doesn't work with double quotes correctly.
Also, to really get a grip on how to use regexs, I would check out Mastering Regular Expressions by Jeffrey Friedl ISBN-13:978-0596528126
Since you are using PHP, I would try to get the 3rd Edition since it has a section specifically on PHP PCRE. Just make sure to read the first 6 chapters first since they give you the foundation needed to work with the material in that particular chapter. If you see the 2nd Edition on the cheap somewhere, that pretty much the same core material, so it would be a good buy as well.