PHP/Zend: How to remove all chars from a string and keep only numbers

Question

I want to keep only numbers and remove all characters from a variable.

For example:

input: +012-(34).56.(ASD)+:"{}|78*9
output: 0123456789

Answer 1

This is how to do that generically:

$numbers = preg_replace('/[^0-9]+/', '', '+012-(34).56.(ASD)+:"{}|78*9');
echo $numbers;

Output:

0123456789

Answer 2

With Zend_Filter_Digits

Returns the string $value, removing all but digit characters.

Example with static call through Zend_Filter:

echo Zend_Filter::filterStatic('abc-123-def-456', 'Digits'); // 123456

Example with Digits instance

$digits = new Zend_Filter_Digits;
echo $digits->filter('abc-123-def-456'); // 123456;

---

Internally, the filter will use preg_replace to process the input string. Depending on if the Regex Engine is compiled with UTF8 and Unicode enabled, one of these patterns will be used:

• [^0-9] - Filter if Unicode is disabled
• [^[:digit:]] - Filter for the value with mbstring
• [\p{^N}] - Filter for the value without mbstring

See http://framework.zend.com/svn/framework/standard/trunk/library/Zend/Filter/Digits.php