Using preg match in my script

Need help!

[spyder_tek]

Below is a script that passes data to a from with a URL, using for example: [www,site,com...]

<?php 
function getIt($value){ 
 if($_GET[$value]){ 
  return $_GET[$value]; 
 }else{ 
  return ""; 
 } 
}?> 
<input type="text" name="price" value="<?php echo getIt("price")?>"> 
<input type="text" name="title" value="<?php echo getIt("title")?>"> 

I'm still learning PHP, so my question is this...

I want to validate my input using preg_match, (I'm assuming this would be the easiest and most secure method).

How can I modify my script so that preg_match:

ONLY accepts numbers, dollar signs and periods from:

<input type="text" name="price" value="<?php echo getIt("price")?>">

and ONLY accepts values containing letters and numbers from:

<input type="text" name="title" value="<?php echo getIt("title")?>">

Finally, how can I modify my script so that preg_match checks "price" and "title" before passing the data from the URL to my form, and if any invalid characters are found the script stops?

Thanks!

[Psychopsia]

A solution to implement regular expressions could be:

function getIt($key, $regex)
{
if (isset($_GET[$key]) &&!empty($_GET[$key]) && preg_match('#' . $regex . '#is', $_GET[$key]))
{
return trim($_GET[$key]);
}

return false;
}

$price = getIt('price', '[0-9\.\$]+');
$title = getIt('title', '[a-zA-Z0-9]+');

if (getIt('price', '[0-9\.\$]+') === false)
{
// Incorrect value
}

[edited by: Psychopsia at 4:03 am (utc) on Dec. 22, 2006]

[eelixduppy]

Then the patterns would be something like this, although you are going to have to fix your function because you want two different checks, not just one for all variables:

$pattern1 = "/^([\d\.\$])+$/"; //allows for numbers, period, dollar sign

and...

$pattern = "/^([\w])+$/"; //allows for alphanumerics and the underscore

Flag this thread [webmasterworld.com]. :)

The problem with Psychopsia's pattern was that it wasn't making sure that the string ONLY contained those values by not asserting the start and end of the subject using ^ and $ respectively.

[Psychopsia]

not asserting the start and end of the subject using ^ and $ respectively.

Yep, you're right! I forget it

[spyder_tek]

Thank you! You helped steer me in the right direction. ;)