warnings in php4

I have a lot of php scripts developed with php3. I've installed php4 and I get some warnings when I evaluate variables there are not set (are empty). In php3 there was no problem (no warning). If I modify the code by using empty($var) or isset($var) it's ok, but there are lots of such issues. How could I manage this without major changes? __________________________________________________ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/