Remove non-numeric characters (excluding periods and commas) from a string (i.e. remove all characters except numbers, commas, and periods)

Question

You could use preg_replace to swap out all non-numeric characters and the comma and period/full stop as follows:

$testString = '12.322,11T';
echo preg_replace('/[^0-9,.]+/', '', $testString);

The pattern can also be expressed as /[^\d,.]+/

I'm surprised there's been no mention of filter_var here for this being such an old question...

PHP has a built in method of doing this using sanitization filters. Specifically, the one to use in this situation is FILTER_SANITIZE_NUMBER_FLOAT with the FILTER_FLAG_ALLOW_FRACTION | FILTER_FLAG_ALLOW_THOUSAND flags. Like so:

$numeric_filtered = filter_var("AR3,373.31", FILTER_SANITIZE_NUMBER_FLOAT,
    FILTER_FLAG_ALLOW_FRACTION | FILTER_FLAG_ALLOW_THOUSAND);
echo $numeric_filtered; // Will print "3,373.31"

It might also be worthwhile to note that because it's built-in to PHP, it's slightly faster than using regex with PHP's current libraries (albeit literally in nanoseconds).

Simplest way to truly remove all non-numeric characters:

echo preg_replace('/\D/', '', $string);

\D represents "any character that is not a decimal digit"

http://php.net/manual/en/regexp.reference.escape.php

You could use filter_var to remove all illegal characters except digits, dot and the comma.

• The FILTER_SANITIZE_NUMBER_FLOAT filter is used to remove all non-numeric character from the string.
• FILTER_FLAG_ALLOW_FRACTION is allowing fraction separator " . "
• The purpose of FILTER_FLAG_ALLOW_THOUSAND to get comma from the string.

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Code

$var1 = '12.322,11T';

echo filter_var($var1, FILTER_SANITIZE_NUMBER_FLOAT, FILTER_FLAG_ALLOW_FRACTION | FILTER_FLAG_ALLOW_THOUSAND);

Output

12.322,11

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To read more about filter_var() and Sanitize filters

If letters are always in the beginning or at the end, you can simply just use trim...no regex needed

$string = trim($string, "a..zA..Z"); // this also take care of lowercase

"AR3,373.31" --> "3,373.31"
"12.322,11T" --> "12.322,11"
"12.322,11"  --> "12.322,11"