strip out non numbers using php

How can I make this query strip out any extra form inputs that aren't numbers for the $_POST[price] ?

Can I alter the below code or is it better to put something in the form input instead? I just want to make sure they only enter positive numbers, so they can't put . or -

$add = doquery("INSERT INTO {{table}} VALUES ('', '$userrow[id]', '$type', '$item', '$_POST[price]';

Code (markup):

 

Use this PHP code to strip each text except for Numbers:

$numbers=ereg_replace("[^0-9]", "", $string);

PHP:

Thanks,
hope it helps!

 

Thanks, how would I write that in here:

<input type='hidden' name='price' value='$_POST[price]' />

 

$numbers=ereg_replace("[^0-9]", "", $_POST['price']);
echo '<input type="hidden" name="price" value="'.$numbers.'" />';

PHP:

 

Thanks, rep added. I couldn't get it to work in the form like that but I used what you showed me like this:

$goodcleannumbers=ereg_replace("[^0-9]", "", $_POST['price']);
			$add = doquery("INSERT INTO {{table}} VALUES ('', '$userrow[id]', '$type', '$item', '.$goodcleannumbers.',...

Code (markup):

Does that look right, it seems to work?

 

Yes, looks right to me.. have a test