PHP Validation

[brendan2b]

I currently have JavaScript functions checking the validation for certain text fields in a form, although with recent browsers you can turn third party scripts off.

I want to check the validation with PHP on the other end, before the information gets processed. Is there anyway to create functions in PHP to check for certain characters or would I need to use already built in string functions to check for length and invalid characters?

Also, I have certain textareas that allows the user to input text, how can i restrict the use of codes other than html? I figured I could check for all the tags such as <?, <script> and <%, and others, but would that really restrict all the code?

Any help would be great, thanks.

[Weedpacket]

You can certainly do server-side validation with PHP (and you certainly should). You can check for the existence or absence of certain characters, check length, check for invalid characters, check they're in the right order; you can do an arbitrary amount of arbitrarily complex checking. There are dozens of string-handling functions that are available.