Online PHP editor | refs for Nmk0t

<?php //test 1 is defined, but has a value of null. isset will return false, use causes no error. $test1 = null; var_dump($test1); var_dump(isset($test1)); echo "\n----------\n\n"; //test2 is defined with a string value. isset will return true $test2 = "test"; var_dump($test2); var_dump(isset($test2)); echo "\n----------\n\n"; //test3 is not defined, isset returns false and use causes error. var_dump($test3); var_dump(isset($test3));