PHP Mailer Script Help - Need a quick line or 2 to allow only Numbers...

I have a simple php mailer script that I've been using. It's been pretty good at blocking spam posts, but I'm getting more and more spam. So I need another line of code or 2 to block letters and only allow Numbers + this character "-" for the Phone number input. Currently, I have these lines of code blocking other forms of form spam:

if(strpos($_POST['comments'], 'http://') !== false) die();
if(strpos($_POST['comments'], '<a') !== false) die();
if(strpos($_POST['phone'], 'http://') !== false) die();
if(strpos($_POST['phone'], '<a') !== false) die();

So this needs to be able to submit:

555-555-5555;

But if it contains any letter, it needs to die.

I appreciate any help. If it gets too complex, I'm not opposed to paying someone.

Thanks!

 

if(!preg_match("|^[0-9-]+|",$_POST['phone'])) die();

 

Thanks a ton dazst! Much appreciated!

 

Or you can use the php build in function is_numeric :

if(!is_numeric($something))die('Not Numeric');

Code (markup):

 

Thank you useful information

 

The problem with is_numeric() is that 0X0046ffcc or 2.43578365+E18 are valid numbers as well. Sometimes you dont want that. In that scenario preg_match is the best way to go..

 

if(!preg_match("|^[0-9-]+|",$_POST['phone'])) die();

it's the best