Listing Declared Variables

Is there an easy way to list the declared variables in a PHP file? I am trying to use the GeoIP PHP script (http://www.maxmind.com) on an existing PHP page. I can use the PHP script on any new pages I create but my existing pages cause the GeoIP include to fail to return any results. I am guessing I have some sort of conflict where I am resetting a variable that GeoIP uses. I just want to quickly compare the defined variables on the GeoIP include with the ones in my existing PHP file with out hunting line by line. Thanks, Dan