PHP Basics

PHP
G. SASIKUMAR
DEPARTMENT OF COMPUTER SCIENCE

OUTLOOK
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INTRODUCTION
USAGE
A SAMPLE
CODE OUTPUT
DATA TYPES
SPEED
OPTIMIZATION
RESOURCES

INTRODUCTION
WHAT IS PHP?
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PHP is a scripting langauge that was originally designed for web
developement to produce dynamic webpages
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For this purpose, PHP code is embedded into HTML
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PHP was created by Rasmus Lerdrof in 1995
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PHP originally stood for ”PERSONAL HOME PAGE”

USAGE
PHP is a general-purpose scripting language that is especially
suited to server-side web development where PHP generally
runs on a web server
PHP code in a requested file is executed by the PHP runtime, usually
to create dynamic web page content
PHP is also 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

A SMALL SAMPLE CODE
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<?php
echo "Hello World";
?>
</body>

OUTPUT
Here the output is ”Hello World”.

PHP only parses code within its delimiters. Anything outside its
delimiters is sent directly to the output and is not processed by
PHP

The most common delimiters are
<?php to open and ?>
<script language="php">
</script>
<?= (which is used to echo back a string or variable) and ?>
<% or <%= and %>.

DATA TYPES

PHP stores whole numbers in a platform-dependent range

This range is typically that of 32-bit signed integers. Unsigned
integers are converted to signed values in certain situations
 Arrays can contain elements of any type that handle in PHP

Including resources, objects, and even other arrays
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PHP also supports strings, which can be used with single quotes,
double quotes, or heredoc syntax

SPEED OPTIMIZATION
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PHP scripts are stored as human-readable source code and are
compiled on-the-fly to an internal format that can be executed by
the PHP engine
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Code optimizers aim to reduce the runtime of the compiled code by
reducing its size and making other changes that can reduce the
execution time with the goal of improving performance

RESOURCES
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PHP includes free and open source libraries
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PHP is a fundamentally Internet-aware system
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Many database servers, embedded SQL libraries such as
embedded PostgreSQL, MySQL and SQLite, LDAP servers, and
others
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PHP allows developers to write extensions in C to add functionality
to the PHP language
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These can then be compiled into PHP or loaded dynamically at runtime

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Usual file extensions .php, .phtml .php5 .phps
Paradigm imperative, object-oriented
Appeared in :1995[1]
Designed by :Rasmus Lerdorf
Developer :The PHP Group
Stable release 5.2.13 / 5.3.2 (5.2.13 February 25, 2010; 37 days ago (2010-02-25) / 5.3.2:
March 4, 2010; 30 days ago (2010-03-04))
Typing discipline Dynamic, weak
Major implementations Zend Engine, Roadsend PHP, Phalanger, Quercus, Project Zero,
HipHop
Influenced by C, Perl, Java, C++, Tcl[1]
Influenced PHP4Delphi
Programming language : C
OS : Cross-platform
License :PHP License
Website :http://www.php.net

A scripting or script language is a programming language that supports scripts:
programs written for a special run-time environment that automate the
execution of tasks that could alternatively be executed one-by-one by a human
operator. Scripting languages are often interpreted (rather than compiled)
A server-side dynamic web page is a web pagewhose construction is
controlled by an application server processing server-side scripts. In server-
side scripting, parameters determine how the assembly of every new web
page proceeds, including the setting up of more client-side processing
"Static" means unchanged or constant, while "dynamic" means changing or
lively. Therefore, static Web pagescontain the same prebuilt content each
time the page is loaded, while the content of dynamic Web pages can be
generated on-the-fly. Standard HTML pages arestatic Web pages

When using the PCRE functions, it is required that the pattern is enclosed
bydelimiters. A delimiter can be any non-alphanumeric, non-backslash, non-
whitespace character. Often used delimiters are forward slashes (/), hash signs
(#) and tildes (~)

PHP Basics

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