PHP Regular Expression - Filter Number Only

PHP regular expression - filter number only

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 );

Using regex to filter year of fixed length 0 or 4 digit

Try the following:

^([0-9]{4})?$

^ - start of line

([0-9]{4})? - four numbers, optionally (because of the ?)

$ - end of line

Using preg_match to filter numbers

This one does the job:

^(?:00|\+)\d{3,}[AF]*$

Explanation:

^           : begining of line
  (?:       : start non capture group
    00      : literally 00
    |       : OR
    \+      : + sign
  )         : end group
  \d{3,}    : 3 or more digits
  [AF]*     : 0 or more letters A or F (change * to + if you want at least one letter)
$           : end of line

In action:

$tests = [
    '00123456789123',
    '+123456789AAAAA',
    '00123FFFFFFFFFF',
    '+123AAAAAAFFA',
    'ABCD',
    '123456F',
    '00123B'
];

foreach($tests as $str) {
    if(preg_match('/^(?:00|\+)\d{3,}[AF]*$/', $str)) {
        echo "$str --> Match\n";
    } else {
        echo "$str --> NO match\n";
    }
}

Output:

00123456789123 --> Match
+123456789AAAAA --> Match
00123FFFFFFFFFF --> Match
+123AAAAAAFFA --> Match
ABCD --> NO match
123456F --> NO match
00123B --> NO match

Trying to filter out non-numeric values with regex in php

You have to use \D to replace the non digits

$re = "/\\D/"; 
$str = "76gg7hg67ku6"; 
$subst = ""; 

$result = preg_replace($re, $subst, $str);

Just fyi:

\D match any character that's not a digit [^0-9]
\d match a digit [0-9]

Working demo

Regex: Select number only ID from email subject

you just have to remove the carret (^) which means begining of the line

/\b(4[0-9]{5})\b/

Also to match only 6 digit "words" you have to add \b which means word boundary.

see https://www.phpliveregex.com/p/pfE

PHP - regex to allow letters and numbers only

1. Use PHP's inbuilt ctype_alnum

You dont need to use a regex for this, PHP has an inbuilt function ctype_alnum which will do this for you, and execute faster:

<?php
$strings = array('AbCd1zyZ9', 'foo!#$bar');
foreach ($strings as $testcase) {
    if (ctype_alnum($testcase)) {
        echo "The string $testcase consists of all letters or digits.\n";
    } else {
        echo "The string $testcase does not consist of all letters or digits.\n";
    }
}
?>

2. Alternatively, use a regex

If you desperately want to use a regex, you have a few options.

Firstly:

preg_match('/^[\w]+$/', $string);

\w includes more than alphanumeric (it includes underscore), but includes all
of \d.

Alternatively:

/^[a-zA-Z\d]+$/

Or even just:

/^[^\W_]+$/

String filtering in php with preg_match and regular expression

Yes, the circumflex goes outside the [] to indicate the start of the string, you probably need an asterisk to allow an arbitrary number of characters, and you probably want a $ at the end to indicate the end of the string:

$tv = preg_match('/^[a-z0-9]*$/', $myval);

If you write [^a-z] it means anything else than a-z.

Extract SKU values which may be numeric or alphanumeric and must be 4 to 20 characters long

Until the regex maestros show up, a lazy person such as myself would just do two rounds on this and keep it simple. First, match all strings that are only A-Z, 0-9 (rather than crafting massive no-lists or look-abouts). Then, use preg_grep() with the PREG_GREP_INVERT flag to remove all strings that are A-Z only. Finally, filter for unique matches to eliminate repeat noise.

$str = '-9 Cycles 3 Temperature Levels Steam Sanitizet+ -Sensor Dry | ALSO AVAILABLE (PRICES MAY VARY) |- White - 1258843 - DVE45R6100W {+ Platinum - 1501 525 - DVE45R6100P desirable: 1258843 DVE45R6100W';

$wanted = [];

// First round: Get all A-Z, 0-9 substrings (if any)
if(preg_match_all('~\b[A-Z0-9]{6,24}\b~', $str, $matches)) {

    // Second round: Filter all that are A-Z only
    $wanted = preg_grep('~^[A-Z]+$~', $matches[0], PREG_GREP_INVERT);

    // And remove duplicates:
    $wanted = array_unique($wanted);
}

Result:

array(3) {
    [2] · string(7) "1258843"
    [3] · string(11) "DVE45R6100W"
    [4] · string(11) "DVE45R6100P"
}

Note that I've increased the match length to {6,24} even though you speak of a 4-character match, since your sample string has 4-digit substrings that were not in your "desirable" list.

Edit: I've moved the preg_match_all() into a conditional construct containing the the remaining ops, and set $wanted as an empty array by default. You can conveniently both capture matches and evaluate if matched in one go (rather than e.g. have if(!empty($matches))).

Update: Following @mickmackusa's answer with a more eloquent regex using a lookahead, I was curious over the performance of a "plain" regex with filtering, vs. use of a lookahead. Then, a test case (only 1 iteration at 3v4l to not bomb them, use your own server for more!).

The test case used 100 generated strings with potential matches, run at 5000 iterations using both approaches. Matching results returned are identical. The single-step regex with lookahead took 0.83 sec on average, while the two-step "plain" regex took 0.69 sec on average. It appears that using a lookahead is marginally more costly than the more "blunt" approach.

PHP filter using preg_replace to allow only alphanumerics and some punctuation

$string = ';")<br>kk23?!'; 
$new_string = preg_replace("/[^A-Za-z0-9.!?]/",'',$string);
echo $new_string;

Leaves: letters, numbers, spaces, .!?

---

/* 3 choices. Pick one you like! */
$str = preg_replace("/[^A-Za-z0-9.!? ]/","",$str);
$str = preg_replace("/[^A-Za-z0-9.!?\s]/","",$str);
$str = preg_replace("/[^A-Za-z0-9.!?[:space:]]/","",$str);

---

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