Check for HTML in a $var?

[MtPHP2]

Ok I have a variable which is a form element just submited by a user, who could be malicious. How can I check to see if it contains HTML/JavaScript and other languages? If it does, stop processiong and pull an error. Note I want them to be able to use CSS... Tahnks in advance for any help!

[nnichols]

Use htmlentities() or htmlspecialchars(). If you read the section of the manual relating to these two functions it explains what they do.