webquest php

7/31/2019 WebQuest PHP

1/16

Programming Language

WebQuestPH P PHP: Hypertext Preprocessor

Submitted to:

Eddie Bouy Palad,

IT Department, SCS, MSU-IIT

Submitted by:

Zachary Albia

Elrey Lorea

Michelle Cepada,

BS IT 3


2/16

2 Programming Language WebQuest

HISTORY

PHP originally stood for Personal Home Page. It began in 1994 as a set ofCommon Gateway Interface

binaries written in the C programming language by the Danish/Greenlandic programmer Rasmus Lerdorf.

He initially created these Personal Home Page Tools to replace a small set of Perl scripts he had been

using to maintain his personal homepage. He combined these binaries with his Form Interpreter to create

PHP/FI (Personal Home Page / Forms Interpreter), which had more functionality. PHP/FI included a

larger implementation for the C programming language and could communicate with databases, enabling

the building of simple, dynamic web applications. He released PHP publicly on June 8, 1995 to accelerate

bug location and improve the code. This release was named PHP version 2 and already had the basic

functionality that PHP has today. This included Perl-like variables, form handling, and the ability to embed

HTML. The syntax was similar to Perl but was more limited, simpler, and less consistent.

PHP 3.0 was the first version that closely resembles PHP as we know it today. It was created by

Andi Gutmans and Zeev Suraski in 1997 as a complete rewrite, after they found PHP/FI 2.0 severely

underpowered for developing an eCommerce application they were working on for a University project.

In an effort to cooperate and start building upon PHP/FI's existing user-base, Andi, Rasmus and Zeev

decided to cooperate and announce PHP 3.0 as the official successor of PHP/FI 2.0, and development of

PHP/FI 2.0 was mostly halted. They rewrote the parser in 1997 and formed the base of PHP 3, changing

the language's name to the recursive initialism PHP: Hypertext Preprocessor.

By the winter of 1998, shortly after PHP 3.0 was officially released, Andi Gutmans and Zeev

Suraski had begun working on a rewrite of PHP's core. The design goals were to improve performance of

complex applications, and improve the modularity of PHP's code base. Such applications were made

possible by PHP 3.0's new features and support for a wide variety of third party databases and APIs, but

PHP 3.0 was not designed to handle such complex applications efficiently. The new engine, dubbed 'Zend

Engine' (comprised of their first names, Zeev and Andi), met these design goals successfully, and was first

introduced in mid 1999. PHP 4.0, based on this engine, and coupled with a wide range of additional new


3/16


features, was officially released in May 2000, almost two years after its predecessor, PHP 3.0. In addition

to the highly improved performance of this version, PHP 4.0 included other key features such as support

for many more Web servers, HTTP sessions, output buffering, more secure ways of handling user input

and several new languages constructs.

Late static binding has been missing from PHP and will be added in version 5.3.On July 13, 2004,

PHP 5 was released, powered by the new Zend Engine II. PHP 5 included new features such as improved

support for object-oriented programming, the PHP Data Objects extension (which defines a lightweight

and consistent interface for accessing databases), and numerous performance enhancements. In 2008,

PHP 5 became the only stable version under development.


4/16


GENEALOGY


5/16


TECHNICAL DETAILS

PHP is a general-purpose scripting language that is especially suited for web development. PHP

generally runs on a web server, taking PHP code as its input and creating web pages as output. It can also

be used for command-line scripting and client-side GUI applications. PHP can be deployed on most web

servers, many operating systems and platforms, and can be used with many relational database

management systems. It is available free of charge, and the PHP Group provides the complete source code

for users to build, customize and extend for their own use.

PHP primarily acts as a filter, taking input from a file or stream containing text and/or PHP

instructions and outputs another stream of data; most commonly the output will be HTML. (PHP 4) the

PHP parser compiles input to produce bytecode for processing by the Zend Engine, giving improved

performance over its interpreter predecessor.

Originally designed to create dynamic web pages, PHP's principal focus is server-side scripting,

and it is similar to other server-side scripting languages that provide dynamic content from a web server

to a client. PHP has also attracted the development of many frameworks that provide building blocks and

a design structure to promote rapid application development (RAD).

PHP as a language is imperative and object-oriented (as of PHP 4.0). PHPs typing discipline is

dynamic and weak, i.e., a variables type can easily be changed throughout runtime and a variable can be

used without first being declared. As shown in the genealogy, the language design of PHP is influenced by

C-based and Perl-based languages.

PHP is dynamically typed. That is, the rules are not as strict with variablesthey do not have to be

declared and they can hold any type of object. Variables are case sensitive and their names are preceded

by a dollar sign ($). The variable name is case-sensitive. Variables names cannot start with a number.

Arrays are heterogeneous, meaning a single array can contain objects of more than one type. Variables are

evaluated inside double quotation marks ("), but not inside single quotation marks ('). Functions and


6/16


other expressions are not evaluated inside double quotes but can be added to strings using periods for

concatenation. A period (.) concatenates strings together. Boolean variables have two possible values

True and False, another form of boolean would be replacing true and false with 1 and 0 (respectively)

but is not a standard of coding. Integers are number variables. They are whole numbers that can be

positive, negative, octal, and hexadecimal.

PHP 5 introduces private and protected member variables; they allow you to define the visibility

of class properties. Private and protected methods are also introduced. PHP 5 also introduces abstract

classes and abstract methods. An abstract method only declares the method's signature and does not

provide an implementation. A class that contains abstract methods needs to be declared an abstract class.

(Interfaces) A class may implement an arbitrary list of interfaces. (Object Cloning) If the developer asks to

create a copy of an object by using the reserved word clone, the Zend engine will check if a __clone()

method has been defined or not. (Unified Constructors) PHP 5 introduces a standard way of declaring

constructor methods by calling them by the name __construct(). (Destructors) PHP 5 introduces a

destructor concept similar to that of other object-oriented languages, when the last reference to an object

is destroyed, the object's destructor (a class method named __destruct() that receives no parameters) is

called before the object is freed from memory. PHP 4 had no exception handling. PHP 5 introduces an

exception model similar to that of other programming languages.

PHP treats new lines as whitespace, in the manner of a free-form language (except when inside

string quotes). Statements are terminated only by a semicolon (;) except in a few special cases. //

comment(for single line comment), and /* multi-line comment */(for multiple line comments).

PHP includes a large number of free and open-source libraries with the core build. PHP is a

fundamentally Internet-aware system with modules built in for accessing FTP servers, many database

servers, embedded SQL libraries like embedded MySQL and SQLite, LDAP servers, and others. Many

functions familiar to C programmers such as the printf family are available in the standard PHP build.


7/16


EVALUATION

Readability

Characteristics Rating (1-5) Comments

Simplicity/ Orthogonality Although PHP has a very large feature set of functionsand keywords, it takes a considerable amount of

effort to read and understand PHP code for the same

reason. Also, a lot of PHPs built-in functions are said

to be redundant. This is said to make it difficult to

program in the language without the frequent

consultation of a reference work.

Control Structures PHPs vast feature set includes support for many

control structures. Some of the more uncommon ones

are include(), include_once(), require(),

require_once, and goto all of which allow the

code to execute away from the file/line where the

control statement is used: which could reduce

readability. Also, with include() and require(),

dependencies are created which could lead to difficult

code maintenance. On the other hand, these features

allow a PHP file to be built from several files, which

allow programmers to distribute functionality.

Data type and Structures The weak, dynamic typing of PHP implies that a

variable can change type during runtime. This alsoimplies that data structures in PHP can be

heterogeneous and its contents, dynamically typed at

the same time. Programmers might have to trace

these changes as well and could lead to confusing

code, especially when debugging.

Syntax Design PHP uses the $ sign to name variables which makes it

easier to identify them but because PHP syntax is

influenced by C/Java, its use of braces for pairing

control structures makes it difficult to know which

group is being ended. The language allows keywords

to be used as identifiers, but this could lead to

confusion. Another argument against previous and

current stable versions of PHP is the lack of lexical

scoping and namespaces (available from alpha release

5.3.0 onwards). This implies that for the most part, all

variables are of a global scope and makes for very

awkward, unreadable function names.


8/16


Writability


Simplicity/ Orthogonality With the same consideration to that of PHPs

readability, PHP is infamous for having an unwieldy

number of functions and keywords. On the other

hand, this allows programmers to do things like

connecting to a database with minimal amount of

code.

Support for abstraction Before PHP 3.0, the language had very little support

for abstraction. PHP 3.0 saw the introduction of

object-oriented features, 4.0 introduced refinements

to those features, and 5.0 introduced private and

protected member variables and methods, along with

abstract classes and abstract methods. It alsointroduced a standard way of declaring constructor

and destructors similar to that of other object-

oriented languages, such as C++. In conclusion, while

previous versions of PHP generally lacked features

which support abstraction, these features are slowly

being integrated into the language with every new

release. PHP 5.3.0 in particular promises to include

namespaces to further abstraction support.

Expressivity PHP is an expression-oriented language, in the sense

that almost everything is an expression. For example'$a = 5'. There are two values involved here, the

value of the integer constant '5', and the value of$a

which is being updated to 5. But there's one

additional value involved, the value of the assignment

itself. The assignment itself evaluates to the assigned

value. It means that'$a = 5', is an expression with

the value 5. Thus, writing something like '$b = ($a

= 5)' is like writing '$a = 5; $b = 5; Since

assignments are parsed in a right to left order, you

can also write '$b = $a = 5'.

Generally speaking, there are many ways to do things

in PHP. Printing out a statement can be done with a

wide variety of statements like echo(), print(),

etc. PHP is a very flexible language to code in,

although at the cost of being at times unstable.


9/16


Reliability


Readability PHP is touted by some as a language which is quite

hard to read. With the huge array of built-in functions,

the redundancy of some of those functions, the lack ofnamespaces for PHPs built-in functions, cryptic error

messages, and the difficulty of telling the differences

between the ways those functions work, wading

through PHP code can be quite a challenge.

Writability While PHP may be hard to read, it is easy to write.

PHP is a powerful, expressive language and with each

new release, more features such as support for object-

oriented programming will provide the language with

the expressive power similar to OO languages such as

Java and C++. A major plus often pointed out about

PHP is its ability to allow beginners to get things done.

Type Checking The type of a variable is not usually set by the

programmer; rather, it is decided at runtime by PHP

depending on the context in which that variable is

used. Programmers will often have a hard time trying

to evaluate a particular variable type within complex

variable type computations.

Exception Handling An exception can be thrown, and caught within PHP.

PHP has a strong structure for exception handling like

other object-oriented programming language.

Restricted Aliasing PHP has no restrictions on the use of aliasing. This can

often lead to unintended side effects that are difficult

to detect especially when debugging.


10/16


SAMPLE PROGRAMS

Hello World:

Arithmetic with PHP:


11/16


SCREENSHOTS

Running the Hello World Program:

Program Output:


12/16


INSTALLATION

For this section, we will be introducing the BitNami WAPPStack (Windows, Apache, PostgreSQL,

PHP) as a distributed binary executable installer for PHP, Apache, and PostgreSQL, all running on

Windows XP and can be downloaded from:http://www.bitnami.org/stacks/. WAPPStack is an easy to

install software platform that greatly simplifies the deployment of Open Source web stacks on Windows. It

includes ready-to-run versions of Apache, PostgreSQL, PHP, phpPgAdmin and required dependencies and

installs in minutes. By default the graphical installation mode will be described by the following:

1. You will be greeted by the 'Welcome' screen. Pressing 'Next' will take you to the 'LicenseAgreement' page.
http://www.bitnami.org/stacks/http://www.bitnami.org/stacks/http://www.bitnami.org/stacks/http://www.bitnami.org/stacks/


13/16


2. You must accept the agreement to continue the installation. The next step is to select theinstallation directory. The default installation path will be a folder on your home directory if

you are running the installer as a regular user, or /opt/wappstack-1.1-1, if you are running

the installation as root. If the destination directory does not exist, it will be created as part

of the installation.


14/16


3. After selecting the installation directory you will be asked for the password to the initialPostgreSQL root and postgres accounts. This password cannot be empty.

4. The default listening port for Apache is 8080 and for PostgreSQL is 5432. If those ports arealready in use by other applications, you will be prompted for alternate ports to use.

Remember that if you plan to run both applications as a regular user you should select port

numbers above 1024.


15/16


5. Finally, the installer will ask you for the initial password to access your phpPgAdmininstallation through the web. This password cannot be empty.

6. You are now ready to begin the installation, which will start when you press 'Next'.

7. Once the installation process has been completed, you will see the 'Installation Finished'page.


16/16


BIBLIOGRAPHY

BitNami WAPP Stack 1.1-1. INSTALLATION. 28 Jan 2009. BitNami. 4 Feb. 2009.

PHP Documentation. 18 Feb 2009. PHP Group.18 Feb. 2009.

w3schools.com. Basic PHP Syntax. 1999-2009. W3Schools. 18 Feb. 2009.

"PHP." Wikipedia. 18 Feb. 2009. Wikimedia Foundation. 18 Feb. 2009.

< http://en.wikipedia.org/wiki/PHP >

Genealogical tree of programming languages. Illustration. Wikimedia Foundation. Maximilian Drrbecker. 18 Feb.

2009.

PHP Criticism. Global Oneness. 18 Feb. 2009.

PHP in contrast to Perl. 18 Feb. 2009.

webquest php

Documents