How To Check A String Has A Valid DATETIME in it?

[eluser]mdavis1982[/eluser]
Hi all...

I'm trying to implement a callback for the validation library that will check whether a string contains a valid DATETIME.

Is there some simple way I'm missing of seeing if the string contains a valid DATETIME? Like a built-in PHP function or something?

Thanks in advance for this... It's probably really simple, but I haven't done any coding for a couple of months so I'm a bit rusty!

Cheers...

Matt