uploaded filenames

[Stooney]

I rarely use regex so I don't know much about em.  Basically I need to take an uploaded file and rename it to only contain alpha numeric characters.  What's the easiest way to replace all non-alpha numeric characters with an underscore?  So...

Jim's Document.txt

 

would become

 

Jim_s_Document.txt

 

The file extension does not need to have characters replaced if it matters.

 

Thanks in advance.

[effigy]

$str = preg_replace('/\W/', '_', $str);

 

\W is shorthand for [^A-Za-z0-9_].