PHP regular expression - filter number only [duplicate]

Question

I know this might sound as really dummy question, but I'm trying to ensure that the provided string is of a number / decimal format to use it later on with PHP's number_format() function.

How would I do it - say someone is typing 15:00 into the text field - what regular expression and php function should I use to remove the colon from it and make it only return the valid characters.

preg_match() returns array - so I can't pass the result to number_format() unless I implode() it or something like this.

Your help would be very much appreciated.

123.4.5 or 123:4\5 or abs:4:5 -> what digit do you want in result? — Dmitrij Golubev
– Dmitrij Golubev, Commented Mar 29, 2011 at 15:16

Avatar · Accepted Answer · 2024-03-30 06:53:50Z

166

Using is_numeric or intval is likely the best way to validate a number here, but to answer your question you could try using preg_replace instead. This example removes all non-numeric characters:

$output = preg_replace('/[^0-9]/', '', $string);

edited Mar 30, 2024 at 6:53

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answered Mar 29, 2011 at 14:27

buley

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4 Comments

buley Over a year ago

Just put a "." inside the [brackets]. E.g. '/[^.0-9]/' -- note that if it's outside the brackets it will become a wildcard. And, this will cover 90% of your use case but will also allow any order so edge cases like "123." and ".123" will work. A good idea is to test out your regexes against examples you know should or should not fail. A site like this one works great.

sdlins Over a year ago

Besides the website cited by @buley, another very good one is regex101.com!

user1642018 Over a year ago

i was using intval on big int, and it was giving me max int value which is 2147483647, so this works good for me.,

Tom De Roo Over a year ago

It's nice to know that in the current day and age one can replace [^0-9] with \D

netcoder · Accepted Answer · 2011-03-29 14:27:44Z

47

To remove anything that is not a number:

$output = preg_replace('/[^0-9]/', '', $input);

Explanation:

[0-9] matches any number between 0 and 9 inclusively.
^ negates a [] pattern.
So, [^0-9] matches anything that is not a number, and since we're using preg_replace, they will be replaced by nothing '' (second argument of preg_replace).

answered Mar 29, 2011 at 14:27

netcoder

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Comments

Madjid Boudis · Accepted Answer · 2021-02-20 23:57:27Z

18

This is the right answer

preg_match("/^[0-9]+$/", $yourstr);

This function return TRUE(1) if it matches or FALSE(0) if it doesn't

Quick Explanation :

'^' : means that it should begin with the following ( in our case is a range of digital numbers [0-9] ) ( to avoid cases like ("abdjdf125") )

'+' : means there should be at least one digit

'$' : means after our pattern the string should end ( to avoid cases like ("125abdjdf") )

answered Feb 20, 2021 at 23:57

Madjid Boudis

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SileNT · Accepted Answer · 2011-03-29 14:28:15Z

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You can try that one:

$string = preg_replace('/[^0-9]/', '', $string);

Cheers.

answered Mar 29, 2011 at 14:28

SileNT

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Samuel Terra · Accepted Answer · 2020-03-12 17:48:41Z

4

Another way to get only the numbers in a regex string is as shown below:

$output = preg_replace("/\D+/", "", $input);

answered Mar 12, 2020 at 17:48

Samuel Terra

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2 Comments

kjones Over a year ago

does anyone know where the PHP documentation for the \D special character is? I can only find mention of it in this note: php.net/manual/en/function.preg-replace.php#89364 but would like to find the actual docs for it - thank you

alvaro.canepa Over a year ago

Character d Meaning: Matches a number, equivalent to [0–9]. For example: /d/ or /[0–9]/ matches ‘2’ in “B2 is the suite number.” Character D Meaning: Matches any non-numeric, equivalent to [0-9]. For example: /D/ or /[0-9]/ matches ‘B’ in “B2 is the suite number.” Source: medium.com/@mena.meseha/…

Luke · Accepted Answer · 2012-08-03 23:59:59Z

3

use built in php function is_numeric to check if the value is numeric.

edited Aug 3, 2012 at 23:59

Luke

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answered Mar 29, 2011 at 14:28

Headshota

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3 Comments

user398341 Over a year ago

I'm using is_numeric - but this only return boolean - so if it's not I'm left with no value. The problem I'm facing here is that during testing of the application someone has typed the colon (:) instead of dot (.) as decimal separator - and this has caused an error with number_format()

Dmitrij Golubev Over a year ago

123.4.5 -> what digit will be?

Stack Overflow Over a year ago

is_numeric will return true for -234, -10 and so on.

Kyle Coots · Accepted Answer · 2016-07-31 00:25:02Z

0

You could do something like this if you want only whole numbers.

function make_whole($v){
    $v = floor($v);
    if(is_numeric($v)){
      echo (int)$v;
      // if you want only positive whole numbers
      //echo (int)$v = abs($v);
    }
}

answered Jul 31, 2016 at 0:25

Kyle Coots

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