[PHP] pobierz, plaintext 
<?php
    $testString = "hah23ferf$%$^6443gt*&&%%$";
    echo preg_replace("/[^0-9]/", "", $testString); // Zwróci 236443
?>
[PHP] pobierz, plaintext 

[PHP] pobierz, plaintext 
preg_replace("/[^0-9,.]/", "", $testString);
[PHP] pobierz, plaintext