Difference Between Php4 And Php5 what is the difference PHP4 and PHP5

I didn't understand actual difference between PHP4 and PHP5. So if any master in PHP language please tell me the actual difference between PHP4 and PHP5. And why we are using PHP instead of ASP.NET and ASP.

PHP5 is an upgraded version of PHP4. before you can possible include a file multiple of times on 1 page and you must load all the file libraries when you want to use them regardless if you really need to use them or not. on PHP5, you can put a code that will tell PHP to include a file only if it was not loaded yet by any part of your page and it contains a class that you are going to use.

 

PHP5 is also faster than PHP4 on lots of aspects and gives a lot of improvements on class creations and scope.

 

Class methods and properties now have visibility.

PHP has 3 levels of visibility:

Public is the most visible, making methods accessible to everyone and properties readable and writable by everyone.

Protected makes members accessible to the class itself and any subclasses as well as any parent classes.

Private makes members only available to the class itself.

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Technically, it is bad to use ASP since it is very prone to hijacking and the server that runs it can be easily crashed by using 'buffer overflow' methods. When the server crash there is a small time window where its security can be breached and plant a file that the attacker will use to upload more files.

 

ASP.NET more stable than ASP alone but it also comes with a price. If an attacker manage to bypass the 'strong' (please note of the quotes) security of ASP.NET, the attacker will gain full admin access to your server. This weak implementation is base from the truth that all .NET programs runs default on admin access. This is not a problem when you are working with your desktop but a great problem when you are online serving webpages.

 

When you are serving webpages, no stranger must be able to get admin access to your server since it will mean total trouble. When IIS loads ASP.NET, your IIS may be running on limited access but once ASP.NET runs, it will run at the systems level promoting all access to admin and system level. While the security protection of IIS and .NET was good at protecting you from attackers, it can be easily crashed. This was patched up on some IIS versions and .NET versions but not the ASP.NET implementation.