I have to create regex to match ugly abbreviations and numbers. These can be one of following "formats":
1) [any alphabet char length of 1 char][0-9]
2) [double][whitespace][2-3 length of any alphabet char]
I tried to match double:
preg_match("/^-?(?:\d+|\d*\.\d+)$/", $source, $matches);
But I coldn't get it to select following example: 1.1 AA My test title. What is wrong with my regex and how can I add those others to my regex too?
In your regex you say "start of string, followed by maybe a - followed by at least one digit or followed by 0 or more digits, followed by a dot and followed by at least one digit and followed by the end of string.
So you regex could match for example.. 4.5, -.1 etc. This is exactly what you tell it to do.
You test input string does not match since there are other characters present after the number 1.1 and even if it somehow magically matched your "double" matching regex is wrong.
For a double without scientific notation you usually use this regex :
[-+]?\b[0-9]+(\.[0-9]+)?\b
Now that we have this out of our way we need a whitespace \s and
[2-3 length of alphabet]
Now I have no idea what [2-3 length of alphabet] means but by combining the above you get a regex like this :
[-+]?\b[0-9]+(\.[0-9]+)?\b\s[2-3 length of alphabet]
You can also place anchors ^$ if you want the string to match entirely :
^[-+]?\b[0-9]+(\.[0-9]+)?\b\s[2-3 length of alphabet]$
Feel free to ask if you are stuck! :)
I see multiple issues with your regex:
You try to match the whole string (as a number) by the anchors: ^ at the beginning and $ at the end. If you don't want that, remove those.
The number group is non-catching. It will be checked for matches, but those won't be added to $matches. That's because of the ?: internal options you set in (?:...). Remove ?: to make that group catching.
You place the shorter digit-pattern before the longer one. If you swap the order, the regex engine will look for it first and on success prefer it over the shorter one.
Maybe this already solves your issue:
preg_match("/-?(\d*\.\d+|\d+)/", $source, $matches);
Demo
Related
regarding to this post "https://stackoverflow.com/questions/35413960/regular-expression-match-all-except-first-occurence" I'm wondering how to find the first occurence on a string only if it start's with a specfic character in PHP.
I would like to sanitize phonenumbers. Example bad phone number:
+49+12423#23492#aosd#+dasd
Regex to remove all "+" except first occurence.
\G(?:\A[^\+]*\+)?+[^\+]*\K\+
Problem: it should remove every "+" only if it starts with "+" not if the first occurence-position is greater than 1.
The regex to remove everything except numbers is easy:
[^0-9]*
But I don't know how to combine those two within one regex. I would just use preg_replace() twice.
Of course I would be able to use a workaround like if ($str[0] === '+') {...} but I prefer to learn some new stuff (regex :)
Thanks for helping.
You can use
(?:\G(?!\A)|^\+)[^+]*\K\+
See the regex demo. Details:
(?:\G(?!\A)|^\+) - either the end of the preceding successful match or a + at the start of string
[^+]* - zero or more chars other than +
\K - match reset operator discarding the text matched so far
\+ - a + char.
See the PHP demo:
$re = '/(?:\G(?!\A)|^\+)[^+]*\K\+/m';
$str = '+49+12423#23492#aosd#+dasd';
echo preg_replace($re, '', $str);
// => +4912423#23492#aosd#dasd
You seem to want to combine the two queries:
A regex to remove everything except numbers
A regex to remove all "+" except first occurence
Here is my two cents:
(?:^\+|\d)(*SKIP)(*F)|.
Replace what is matched with nothing. Here is an online demo
(?:^\+|\d) - A non-capture group to match a starting literal plus or any digit in the range from 0-9.
(*SKIP)(*F) - Consume the previous matched characters and fail them in the rest of the matching result.
| - Or:
. - Any single character other than newline.
I'd like to think that this is a slight adaptation of what some consider "The best regex trick ever" where one would first try to match what you don't want, then use an alternation to match what you do want. With the use of the backtracking control verbs (*SKIP)(*F) we reverse the logic. We first match what we do want, exclude it from the results and then match what we don't want.
I need a regular expression to detect the phrase Figure 1.5: in a given string. Also, I intend on using this expression in a PHP preg_replace() function.
Here are some more examples:
...are given. Figure 2.1: shows that...
...are given. Figure 3: shows that...
...are given. Figure 1.16: shows that...
...are given. Figure 0.4 shows that...
...are given. figure 5.1: shows that...
With my limited Regex knowledge, I was able to create this:
/\wFigure \d*\.?\d*/g
But that doesn't even begin to handle all of the permutations that could occur.
I would appreciate any suggestions that you might have.
There are several points here:
You are using \w at the start, perhaps, as a word boundary. In fact, \w matches a letter, digit or _ and actually requires this char to be at the exact location. However, there is no word char before Figure, so you need to either remove \w or replace with \b.
preg_replace replaces all non-overlapping occurrences by default, you do not need the g modifier
\d*\.?\d* is fine here, but since you want to match any digits followed with zero or more occurrences of . and digits you can use a more specific pattern like \d+(?:\.\d+)*.
You can use
preg_replace('/Figure \d+(?:\.\d+)*/', '', $string)
See the regex demo.
Details:
Figure - a string
- a space (replace with \s+ to match any one or more whitespaces, and consider adding u flag after last / if you need to find all Unicode whitespaces)
\d+ - one or more digits
(?:\.\d+)* - zero or more occurrences of . and one or more digits.
I have a piece of data, retrieved from the database and containing information I need. Text is entered in a free form so it's written in many different ways. The only thing I know for sure is that I'm looking for the first number after a given string, but after that certain string (before the number) can be any text as well.
I tried this (where mytoken is the string I know for sure its there) but this doesn't work.
/(mytoken|MYTOKEN)(.*)\d{1}/
/(mytoken|MYTOKEN)[a-zA-Z]+\d{1}/
/(mytoken|MYTOKEN)(.*)[0-9]/
/(mytoken|MYTOKEN)[a-zA-Z]+[0-9]/
Even mytoken can be written in capitals, lowercase or a mix of capitals and lowercase character. Can the expression be case insensitive?
You do not need any lazy matching since you want to match any number of non-digit symbols up to the first digit. It is better done with a \D*:
/(mytoken)(\D*)(\d+)/i
See the regex demo
The pattern details:
(mytoken) - Group 1 matching mytoken (case insensitively, as there is a /i modifier)
(\D*) - Group 2 matching zero or more characters other than a digit
(\d+) - Group 3 matching 1 or more digits.
Note that \D also matches newlines, . needs a DOTALL modifier to match across newlines.
You need to use a lazy quantifier. You can do that by putting a question mark after the star quantifier in the regex: .*?. Otherwise, the numbers will be matched by the dot operator until the last number, which will be matched by \d.
Regex: /(mytoken|MYTOKEN)(.*?)\d/
Regex demo
You can use the opposite:
/(mytoken|MYTOKEN)(\D+)(\d)/
This says: mytoken, followed by anything not a number, followed by a number. The (lazy) dot-star-soup is not always your best bet. The desired number will be in $3 in this example.
I have user-entered text with potentially mistyped "tokens" I'm trying to find using PHP.
A valid "token" is any number of word characters wrapped in percent signs - so %blah% %blah_moreblah%. Basically I'm looking for tokens where the user may have forgotten to put a leading or trailing '%'. I'm also looking for tokens in the valid format - as at this point in my code, all replaceable tokens have already been replaced.
So, the 3 situations I'm looking for are (to borrow regex syntax): %\w+, %\w+%, or \w+%.
In English, what I'm looking for is, "a string that starts with a % and/or ends with a % and contains only word characters'
The regex I have this far is: (%*\w+%*), but you'll notice it matches every single word. I'm stuck on making a match require at least a leading or a trailing %.
Edit: Initially I tried to have all 3 situations found with their own regex. However, I was finding that the regex for finding tokens in the first situation would also find tokens in the second situation, just without the trailing %. For example, /(%\w+)/, when checked against %before %both%, would match %before and %both.
To match tokens enclosed with %, or having % on either side, use
(?=\w*%)%*\w+%*
See another regex demo.
This is your pattern that I added a positive lookahead to. The (?=\w*%) restricts to only such matches where a % appears after a zero or more occurrences of word characters.
Note also that %* will match zero or more percent signs, it may match %%%word%%. If it is not what you need, and if you need to match 1 or 0 %s, just replace the * with ? quantifier.
Try this:
$input_lines = "Hello this is a %string% with %some_words in it just for demo% purposes.";
preg_match_all("/\s[\w_\-]+%\.?|%[\w_\-]+(%|\s|\.)/", $input_lines, $output_array);
That will output this:
array(
0 => %string%
1 => %some_words
2 => demo%
)
Note that this will catch the valid cases, as well as the typos you are looking for.
I am using PHP.
I have a strings like:
example.123.somethingelse
example.1234.somethingelse
example.2015.123.somethingelse
example.2015.1234.somethingelse
and I came up with this regex
/example\.(2015\.|)([0-9]{3,4})\./
What I want to get is "123" or "1234" and it works for these strings. But when the string is
example.2015.A01.somethingelse
the result is "2015".
The way that I see it, after "2015." I have "A" and this should not be matched by the regex, but it is ( and I suppose there is a solid reason for it that I dont understand atm).
How can I fix it ( make the regex match nothing since the last string does not follow the same structure as the others) ?
Your regex is this:
/example\.(2015\.|)([0-9]{3,4})\./
That says
First match "example" followed by a period
Then match either "2015" followed by a period OR nothing at all.
Then match 3 or 4 digits in a row followed by a period
When you have the string example.2015.A01.somethingelse it matches the "example.2015." but then, as you said, the "A" messes it up so it backtracks and matches just "example." (remember the "OR" allowed for nothing to be matched). So it matches "example." followed by NOTHING followed by 3 or 4 numeric digits -- since "2015" is 4 numeric digits it comfortably matches "example.2015".
It's hard to tell from your description, but I think you've just got a mis-placed vertical bar:
/example\.(2015\.)|([0-9]{3,4})\./
That should match EITHER "example.2015." OR numbers like 123 -- but "2015" is still 4 numeric digits in a row, so it will still match. I don't have a clear enough idea of the pattern to figure out how that could be avoided.
Maybe use \d+ and take the first result in the array.
In your regex, you use the following:
(2015\.|)
This allows the regex to match either 2015. or the empty string (zero characters).
When the regex example\.(2015\.|)([0-9]{3,4})\. is applied to the following example:
example.2015.A01.somethingelse
it will to match the literal characters example, and then the empty string with (2015\.|) and then uses ([0-9]{3,4})\. to match the string 2015, which is 4 numerical characters. Thus your expression matches the following:
example.2015.
Looks like you need a possessive quantifier:
/example\.(2015\.)?+([0-9]{3,4})\./
The 2015. is still optional, but once the regex has matched it, it won't give it up, even if that causes the match to fail. I'm assuming the substring you're trying to capture with ([0-9]{3,4}) can never have the value 2015. That is, you won't need to match something like this:
example.2015.somethingelse
If that's not the case, it's going to be much more complicated.
here is one more pattern
example\.(?:2015\.)?\K(\d+)
Demo
or to your specific amount of digits
example\.(?:2015\.)?\K(\d{3,4})