I'm trying to remove / detect phone numbers from messages between users of my marketplace website (think eBay does something similar)
this is the code I'm using:
$string = preg_replace('/([0-9]+[\- ]?[0-9]+)/', '', $string);
BUT... it's too aggressive and it does strip away any number with 2 or more numerals... how can set a limit of say 7 numbers instead?
to be more precise the phone numbers can be any format like
3747657654
374-7657654
374-765-7654
(374)765-7654
etc...(i cannot predict what the users will write depending of their habits)
Try this regular expression :
/([0-9]+[\- ]?[0-9]{6,})/
changed to match your samples:
Regex101
That would depend on the exact requirements as now you have 1 or more numbers followed by an optional - or space followed by 1 or more numbers again.
If you wanted for example at least 2 numbers before the space or - followed by at least 5 numbers, you could use something like:
$string = preg_replace('/([0-9]{2,}[\- ]?[0-9]{5,})/', '', $string);
^^^^ Here you can specify mininimum / maximum
^^^^ Here you can specify mininimum / maximum
You can try something like this:
$string = preg_replace('/(?<![0-9]|[0-9]-)[0-9](?:[- ]?[0-9]){6}(?!-?[0-9])/', '', $string);
The lookarounds are here to avoid numbers with more than 7 digits, but if you want something more specific, you should provide an example string.
It is impossible to determine whether a number of X digits (where X is a valid phone number length) is a phone number or something else without some sort of context intelligence happening. A simple regex can't determine the difference between "call me at 3453456" and "call me when you've flown 3453456 miles".
Therefore trying to catch phone numbers without any formatting (just straight digits) with a regex is hopeless, pure and simple. Attempting to do so is only holding you back from finding a regex that can find formatted/semi-formatted numbers. What you should be going for here is "get the obvious and as many others as possible with minimal false positives...but recognize I can't get them all."
For that I'd recommend this:
/1?[ \-]?\(?([0-9]{3})?\)?[ \-]?([0-9]{3})[ \-]([0-9]{4})/g
It should not get the first three, but get all the rest in this list:
no-match: 3747657654
no-match: 444444444444444
no-match: 7657654
match: 374-765-7654
match: 1-374-765-7654
match: (374)765-7654
match: (374) 765 7654
match: 765-7654
match: 1 (374) 765 7654
match: 1(374)765 7654
Is there a function or a easy way to strip down phone numbers to a specific format?
Input can be a number (mobile, different country codes)
maybe
+4917112345678
+49171/12345678
0049171 12345678
or maybe from another country
004312345678
+44...
Im doing a
$mobile_new = preg_replace("/[^0-9]/","",$mobile);
to kill everything else than a number, because i need it in the format 49171 (without + or 00 at the beginning), but i need to handle if a 00 is inserted first or maybe someone uses +49(0)171 or or inputs a 0171 (needs to be 49171.
so the first numbers ALWAYS need to be countryside without +/00 and without any (0) between.
can someone give me an advice on how to solve this?
You can use
(?:^(?:00|\+|\+\d{2}))|\/|\s|\(\d\)
to match most of your cases and simply replace them with nothing. For example:
$mobile = "+4917112345678";
$mobile_new = preg_replace("/(?:^(?:00|\+|\+\d{2}))|\/|\s|\(\d\)/","",$mobile);
echo $mobile_new;
//output: 4917112345678
regex101 Demo
Explanation:
I'm making use of OR here, matching each of your cases one by one:
(?:^(?:00|\+|\+\d{2})) matches 00, + or + followed by two numbers at the beginning of your string
\/ matches a / anywhere in the string
\s matches a whitspace anywhere in the string (it matches the newline in the regex101 demo, but I suppose you match each number on its own)
\(\d\) matches a number enclosed in brackets anywhere in the string
The only case not covered by this regex is the input format 01712345678, as you can only take a guess what the country specific prefix can be. If you want it to be 49 by default, then simply replace each input starting with a single 0 with the 49:
$mobile = "01712345678";
$mobile_new = preg_replace("/^0/","49",$mobile);
echo $mobile_new;
//output: 491712345678
This pattern (49)\(?([0-9]{3})[\)\s\/]?([0-9]{8}) will split number in three groups:
49 - country code
3 digits - area code
8 digits - number
After match you can construct clean number just concatnating them by \1\2\3.
Demo: https://regex101.com/r/tE5iY3/1
If this not suits you then please explain more precisely what you want with test input and expected output.
I recommend taking a look at LibPhoneNumber by Google and its port for PHP.
It has support for many formats and countries and is well-maintained. Better not to figure this out yourself.
https://github.com/giggsey/libphonenumber-for-php
$phoneUtil = \libphonenumber\PhoneNumberUtil::getInstance();
$usNumberProto = $phoneUtil->parse("+1 650 253 0000", "US");
I am trying to detect with regex, strings that have a pattern of {any_number}{x-}{large|medium|small} for a site with clothing I am building in PHP.
I have managed to match the sizes against a preconfigured set of strings by using:
$searchFor = '7x-large';
$regex = '/\b'.$searchFor.'\b/';
//Basically, it's finding the letters
//surrounded by a word-boundary (the \b bits).
//So, to find the position:
preg_match($regex, $opt_name, $match, PREG_OFFSET_CAPTURE);
I even managed to detect weird sizes like 41 1/2 with regex, but I am not an expert and I am having a hard time on this.
I have come up with
preg_match("/^(?<![\/\d])([xX\-])(large|medium|small)$/", '7x-large', $match);
but it won't work.
Could you pinpoint what I am doing wrong?
It sounds like you also want to match half sizes. You can use something like this:
$theregex = '~(?i)^\d+(?:\.5)?x-(?:large|medium|small)$~';
if (preg_match($theregex, $yourstring,$m)) {
// Yes! It matches!
// the match is $m[0]
}
else { // nah, no luck...
}
Note that the (?i) makes it case-insensitive.
This also assumes you are validating that an entire string conforms to the pattern. If you want to find the pattern as a substring of a larger string, remove the ^ and $ anchors:
$theregex = '~(?i)\d+(?:\.5)?x-(?:large|medium|small)~';
Look at the specification you have and build it up piece by piece. You want "{any_number}{x-}{large|medium|small}".
"{any_number}" would be \d+. This does not allow fractional numbers such as 12.34, but the question does not specify whether they are required.
"{x-}" is a simple string x-
"{large|medium|small}" is a choice between three alternatives large|medium|small.
Joining the pieces together gives \d+x-(large|medium|small). Note the brackets around the alternation, without then the expression would be interpreted as (\d+x-large)|medium|small.
You mention "weird sizes like 41 1/2" but without specifying how "weird" the number to be matched are. You need a precise specification of what you include in "weird" before you can extend the regular expression.
I'm just getting to know regular expressions, but after doing quite a bit of reading (and learning quite a lot), I still have not been able to figure out a good solution to this problem.
Let me be clear, I understand that this particular problem might be better solved not using regular expressions, but for the sake of brevity let me just say that I need to use regular expressions (trust me, I know there are better ways to solve this).
Here's the problem. I'm given a big file, each line of which is exactly 4 characters long.
This is a regex that defines "valid" lines:
"/^[AB][CD][EF][GH]$/m"
In english, each line has either A or B at position 0, either C or D at position 1, either E or F at position 2, and either G or H at position 3. I can assume that each line will be exactly 4 characters long.
What I'm trying to do is given one of those lines, match all other lines that contain 2 or more common characters.
The below example assumes the following:
$line is always a valid format
BigFileOfLines.txt contains only valid lines
Example:
// Matches all other lines in string that share 2 or more characters in common
// with "$line"
function findMatchingLines($line, $subject) {
$regex = "magic regex I'm looking for here";
$matchingLines = array();
preg_match_all($regex, $subject, $matchingLines);
return $matchingLines;
}
// Example Usage
$fileContents = file_get_contents("BigFileOfLines.txt");
$matchingLines = findMatchingLines("ACFG", $fileContents);
/*
* Desired return value (Note: this is an example set, there
* could be more or less than this)
*
* BCEG
* ADFG
* BCFG
* BDFG
*/
One way I know that will work is to have a regex like the following (the following regex would only work for "ACFG":
"/^(?:AC.{2}|.CF.|.{2}FG|A.F.|A.{2}G|.C.G)$/m"
This works alright, performance is acceptable. What bothers me about it though is that I have to generate this based off of $line, where I'd rather have it be ignorant of what the specific parameter is. Also, this solution doesn't scale terrible well if later the code is modified to match say, 3 or more characters, or if the size of each line grows from 4 to 16.
It just feels like there's something remarkably simple that I'm overlooking. Also seems like this could be a duplicate question, but none of the other questions I've looked at really seem to address this particular problem.
Thanks in advance!
Update:
It seems that the norm with Regex answers is for SO users to simply post a regular expression and say "This should work for you."
I think that's kind of a halfway answer. I really want to understand the regular expression, so if you can include in your answer a thorough (within reason) explanation of why that regular expression:
A. Works
B. Is the most efficient (I feel there are a sufficient number of assumptions that can be made about the subject string that a fair amount of optimization can be done).
Of course, if you give an answer that works, and nobody else posts the answer *with* a solution, I'll mark it as the answer :)
Update 2:
Thank you all for the great responses, a lot of helpful information, and a lot of you had valid solutions. I chose the answer I did because after running performance tests, it was the best solution, averaging equal runtimes with the other solutions.
The reasons I favor this answer:
The regular expression given provides excellent scalability for longer lines
The regular expression looks a lot cleaner, and is easier for mere mortals such as myself to interpret.
However, a lot of credit goes to the below answers as well for being very thorough in explaining why their solution is the best. If you've come across this question because it's something you're trying to figure out, please give them all a read, helped me tremendously.
Why don't you just use this regex $regex = "/.*[$line].*[$line].*/m";?
For your example, that translates to $regex = "/.*[ACFG].*[ACFG].*/m";
This is a regex that defines "valid" lines:
/^[A|B]{1}|[C|D]{1}|[E|F]{1}|[G|H]{1}$/m
In english, each line has either A or B at position 0, either C or D
at position 1, either E or F at position 2, and either G or H at
position 3. I can assume that each line will be exactly 4 characters
long.
That's not what that regex means. That regex means that each line has either A or B or a pipe at position 0, C or D or a pipe at position 1, etc; [A|B] means "either 'A' or '|' or 'B'". The '|' only means 'or' outside of character classes.
Also, {1} is a no-op; lacking any quantifier, everything has to appear exactly once. So a correct regex for the above English is this:
/^[AB][CD][EF][GH]$/
or, alternatively:
/^(A|B)(C|D)(E|F)(G|H)$/
That second one has the side effect of capturing the letter in each position, so that the first captured group will tell you whether the first character was A or B, and so on. If you don't want the capturing, you can use non-capture grouping:
/^(?:A|B)(?:C|D)(?:E|F)(?:G|H)$/
But the character-class version is by far the usual way of writing this.
As to your problem, it is ill-suited to regular expressions; by the time you deconstruct the string, stick it back together in the appropriate regex syntax, compile the regex, and do the test, you would probably have been much better off just doing a character-by-character comparison.
I would rewrite your "ACFG" regex thus: /^(?:AC|A.F|A..G|.CF|.C.G|..FG)$/, but that's just appearance; I can't think of a better solution using regex. (Although as Mike Ryan indicated, it would be better still as /^(?:A(?:C|.E|..G))|(?:.C(?:E|.G))|(?:..EG)$/ - but that's still the same solution, just in a more efficiently-processed form.)
You've already answered how to do it with a regex, and noted its shortcomings and inability to scale, so I don't think there's any need to flog the dead horse. Instead, here's a way that'll work without the need for a regex:
function findMatchingLines($line) {
static $file = null;
if( !$file) $file = file("BigFileOfLines.txt");
$search = str_split($line);
foreach($file as $l) {
$test = str_split($l);
$matches = count(array_intersect($search,$test));
if( $matches > 2) // define number of matches required here - optionally make it an argument
return true;
}
// no matches
return false;
}
There are 6 possibilities that at least two characters match out of 4: MM.., M.M., M..M, .MM., .M.M, and ..MM ("M" meaning a match and "." meaning a non-match).
So, you need only to convert your input into a regex that matches any of those possibilities. For an input of ACFG, you would use this:
"/^(AC..|A.F.|A..G|.CF.|.C.G|..FG)$/m"
This, of course, is the conclusion you're already at--so good so far.
The key issue is that Regex isn't a language for comparing two strings, it's a language for comparing a string to a pattern. Thus, either your comparison string must be part of the pattern (which you've already found), or it must be part of the input. The latter method would allow you to use a general-purpose match, but does require you to mangle your input.
function findMatchingLines($line, $subject) {
$regex = "/(?<=^([AB])([CD])([EF])([GH])[.\n]+)"
+ "(\1\2..|\1.\3.|\1..\4|.\2\3.|.\2.\4|..\3\4)/m";
$matchingLines = array();
preg_match_all($regex, $line + "\n" + $subject, $matchingLines);
return $matchingLines;
}
What this function does is pre-pend your input string with the line you want to match against, then uses a pattern that compares each line after the first line (that's the + after [.\n] working) back to the first line's 4 characters.
If you also want to validate those matching lines against the "rules", just replace the . in each pattern to the appropriate character class (\1\2[EF][GH], etc.).
People may be confused by your first regex. You give:
"/^[A|B]{1}|[C|D]{1}|[E|F]{1}|[G|H]{1}$/m"
And then say:
In english, each line has either A or B at position 0, either C or D at position 1, either E or F at position 2, and either G or H at position 3. I can assume that each line will be exactly 4 characters long.
But that's not what that regex means at all.
This is because the | operator has the highest precedence here. So, what that regex really says, in English, is: Either A or | or B in the first position, OR C or | or D in the first position, OR E or | or F in the first position, OR G or '|orH` in the first position.
This is because [A|B] means a character class with one of the three given characters (including the |. And because {1} means one character (it is also completely superfluous and could be dropped), and because the outer | alternate between everything around it. In my English expression above each capitalized OR stands for one of your alternating |'s. (And I started counting positions at 1, not 0 -- I didn't feel like typing the 0th position.)
To get your English description as a regex, you would want:
/^[AB][CD][EF][GH]$/
The regex will go through and check the first position for A or B (in the character class), then check C or D in the next position, etc.
--
EDIT:
You want to test for only two of these four characters matching.
Very Strictly speaking, and picking up from #Mark Reed's answer, the fastest regex (after it's been parsed) is likely to be:
/^(A(C|.E|..G))|(.C(E)|(.G))|(..EG)$/
as compared to:
/^(AC|A.E|A..G|.CE|.C.G|..EG)$/
This is because of how the regex implementation steps through text. You first test if A is in the first position. If that succeeds, then you test the sub-cases. If that fails, then you're done with all those possible cases (or which there are 3). If you don't yet have a match, you then test if C is in the 2nd position. If that succeeds, then you test for the two subcases. And if none of those succeed, you test, `EG in the 3rd and 4th positions.
This regex is specifically created to fail as fast as possible. Listing each case out separately, means to fail, you would have test 6 different cases (each of the six alternatives), instead of 3 cases (at a minimum). And in cases of A not being the first position, you would immediately go to test the 2nd position, without hitting it two more times. Etc.
(Note that I don't know exactly how PHP compiles regex's -- it's possible that they compile to the same internal representation, though I suspect not.)
--
EDIT: On additional point. Fastest regex is a somewhat ambiguous term. Fastest to fail? Fastest to succeed? And given what possible range of sample data of succeeding and failing rows? All of these would have to be clarified to really determine what criteria you mean by fastest.
Here's something that uses Levenshtein distance instead of regex and should be extensible enough for your requirements:
$lines = array_map('rtrim', file('file.txt')); // load file into array removing \n
$common = 2; // number of common characters required
$match = 'ACFG'; // string to match
$matchingLines = array_filter($lines, function ($line) use ($common, $match) {
// error checking here if necessary - $line and $match must be same length
return (levenshtein($line, $match) <= (strlen($line) - $common));
});
var_dump($matchingLines);
I bookmarked the question yesterday in the evening to post an answer today, but seems that I'm a little late ^^ Here is my solution anyways:
/^[^ACFG]*+(?:[ACFG][^ACFG]*+){2}$/m
It looks for two occurrences of one of the ACFG characters surrounded by any other characters. The loop is unrolled and uses possessive quantifiers, to improve performance a bit.
Can be generated using:
function getRegexMatchingNCharactersOfLine($line, $num) {
return "/^[^$line]*+(?:[$line][^$line]*+){$num}$/m";
}
How can you match the following words by PHP, either by regex/globbing/...?
Examples
INNO, heppeh, isi, pekkep, dadad, mum
My attempt would be to make a regex which has 3 parts:
1st match match [a-zA-Z]*
[a-zA-Z]?
rotation of the 1st match // Problem here!
The part 3 is the problem, since I do not know how to rotate the match.
This suggests me that regex is not the best solution here, since it is too very inefficient for long words.
I think regex are a bad solution. I'd do something with the condition like: ($word == strrev($word)).
Regexs are not suitable for finding palindromes of an arbitrary length.
However, if you are trying to find all of the palindromes in a large set of text, you could use regex to find a list of things that might be palindromes, and then filter that list to find the words that actually are palindromes.
For example, you can use a regex to find all words such that the first X characters are the reverse of the last X characters (from some small fixed value of X, like 2 or 3), and then run a secondary filter against all the matches to see if the whole word is in fact a palindrome.
In PHP once you get the string you want to check (by regex or split or whatever) you can just:
if ($string == strrev($string)) // it's a palindrome!
i think this regexp can work
$re = '~([a-z])(.?|(?R))\1~';