filter/remove metacharacter from a string

[ultra]

Hi,
How can I filter a string by removing characters others than listed below;
a-z,
A-Z,
0-9,
( ) space,
(_) underscore
(-) minus sign

example
'is this $100?' would become 'is this 100'

[Vege]

<?php

$k = "s<>/\email";
$k2 = preg_replace('/[^a-z0-9_-]+/i','', $k);
echo $k2;
?>

Something like this?

[ultra]

exactly... thank you so much