Difference between Abstract class and Interfaces.

Abstract class:

• Abstract class comes under partial abstraction.
• Abstract classes can maintain abstract methods and non abstract methods.
• In abstract classes, we can create the variables.
• In abstract classes, we can use any access specifier.
• By using 'extends' keyword we can access the abstract class features from derived class.
• Multiple inheritance is not possible.

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Interface:

• Interface comes under fully abstraction.
• Interfaces can maintain only abstract methods.
• In interfaces, we can't create the variables.
• In interface, we can use only public access specifier.
• By using 'implement' keyword we can get interface from derived class.
• By using interfaces multiple inheritance is possible.

List of Online PHP Codepads

Yes, there are some. Looking for a PHP version? I was looking for a PHP 5.1 codepad (run PHP code online for test purposes), but was not able to. I remember there was one, but I have not found it.
Here is the list I came up so far before you need to click through hundreds of search results:

Codepad	PHP Version(s)	Note
writecodeonline.com	PHP 4.4.9	Legacy needs?
codepad.org	PHP 5.2.5	Many languages, good history
ideone.com	PHP 5.2.12 (pl0-gentoo)	Many langauges, good history
freephptest.com	PHP 5.2.17	Not very accessible
coderun.com (ide)	PHP 5.3.1	Not suitable for quick testing
phpcodepad.com	PHP 5.3.2	Not very accessible
codepad.viper-7.com	PHP 5.2, PHP 5.3, PHP 5.4 + trunk	A PHP coders paradise

The History of PHP

PHP is an "HTML-embedded scripting language" primarily used for dynamic Web applications. The first part of this definition means that PHP code can be interspersed with HTML, making it simple to generate dynamic pieces of Web pages on the fly. As a scripting language, PHP code requires the presence of the PHP processor. PHP code is normally run in plain-text scripts that will only run on PHP-enabled computers (conversely programming languages can create standalone binary executable files, a.k.a. programs). PHP takes most of its syntax from C, Java, and Perl. It is an open source technology and runs on most operating systems and with most Web servers.

 

 

 

 

 

 

 

PHP was written in the C programming language by Rasmus Lerdorf in 1994 for use in monitoring his online resume and related personal information. For this reason, PHP originally stood for "Personal Home Page". Lerdorf combined PHP with his own Form Interpreter, releasing the combination publicly as PHP/FI (generally referred to as PHP 2.0) on June 8, 1995.

Two programmers, Zeev Suraski and Andi Gutmans, rebuilt PHP’s core, releasing the updated result as PHP/FI 2 in 1997. The acronym was formally changed to PHP: HyperText Preprocessor, at this time. (This is an example of a recursive acronym: where the acronym itself is in its own definition.) In 1998, PHP 3 was released, which was the first widely used version.

PHP 4 was released in May 2000, with a new core, known as the Zend Engine 1.0. PHP 4 featured improved speed and reliability over PHP 3. In terms of features, PHP 4 added references, the Boolean type, COM support on Windows, output buffering, many new array functions, expanded object-oriented programming, inclusion of the PCRE library, and more. Maintenance releases of PHP 4 are still available, primarily for security updates.