1. An object with no properties will be deallocate the memory which is allotted while creating the object.

2. The get_class(), get_parent_class() and get_class_methods() are the methods which is used to get the name of the class, base class name which the sub class is extended and list the number of methods in the class respectively, With the case sensitive in manner. The class and method returned was in the lower cased. It may leads to problem with Using the older version. A possible solution is to search for those functions in all your scripts and use strtolower().

3. In PHP5 we can use __construct() as the constructor along with the older style of using the constructor.

4. The ip2long() function is used in the PHP5 version to returns FALSE when an invalid IP address is passed as argument to the function.

5. The include_once() and require_once() first normalize the path of included file hence that including A.php and a.php include the file for the single time. i.e. Standardize the two file and check whether it having the same file name.

6. If there are functions defined in the included file, they can be used in the main file independent if they are before return() or after. If the file is included twice, PHP 5 issues fatal error because functions were already declared, while PHP 4 doesn't complain about it. It is recommended to use include_once() instead of checking if the file was already included and conditionally return inside the included file.

7. PATH_TRANSLATED server variable is no longer set implicitly under Apache2 SAPI in contrast to the situation in PHP 4, where it is set to the same value as the SCRIPT_FILENAME server variable when it is not populated by Apache. This change was made to comply with the CGI specification.

8. The $_SERVER should be along with argc and argv if the configuration of “variables_order” sets to includes "S". If you have specifically configured your system to not create $_SERVER, It will not be their. The change was to always make argc and argv available in the CLI version regardless of the variables_order setting. As in, the CLI version will now always populate the global $argc and $argv variables.

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J.Vijayanand