[Startzero.net]

http://il.php.net/is_numeric

שמה תמצא בטוח,
ואם אתה לא מוצא זה נמצא כאן:

<?php
mynumber = "3" // 3 is a number 
$mynumber = "3.3" // 3.3 is a number 
$mynumber = "-3.3" // -3.3 is a number 
$mynumber = "-0,3" // -0,3 is a number 
$mynumber = "-0,3x" // -0,3x is not a number 

if (preg_match ("/^([0-9.,-]+)$/", $mynumber)) {
     print $mynumber." is a number";
} else {
     print $mynumber." is not a number";
}
?>