By

N. Ajay Kumar

Contents• Introduction• What is PHP?• Features• Uses of PHP• Where it is used?• History of PHP• Implementations• Basics of PHP• An Example• Security Issues• Conclusion

What is PHP?What is PHP?

• PHP• PHP: Hypertext Preprocessor• Originally called “Personal Home Page Tools”• Popular server-side scripting technology• Open-source• Anyone may view, modify and redistribute source

code• Supported freely by community

• Platform independent 3

• Source-code not visible by client• ‘View Source’ in browsers does not display the PHP code

• Various built-in functions allow for fast development• PHP supports many databases (MySQL,

Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc.)• PHP is compatible with almost all servers

used today (Apache, IIS, etc.)

PHP FeaturesPHP Features

• Easy learning• Syntax Perl- and C-like syntax. Relatively easy to

learn.• Large function library• Embedded directly into HTML• Interpreted, no need to compile• Open Source server-side scripting language

designed specifically for the web.

PHP Features(cont.)PHP Features(cont.)• Conceived in 1994, now used on +10 million web

sites.• Outputs not only HTML but can output XML,

images (JPG & PNG), PDF files and even Flash movies all generated on the fly. Can write these files to the file system.• PHP also has support for talking to other services

using protocols such as LDAP, IMAP, SNMP, NNTP, POP3, HTTP.

Using PHP you..• Can performs system functions, i.e. from files on a system

it can create, open, read, write, and close them.• Can handle forms, i.e. gather data from files, save data to

a file, thru email you can send data, return data to the user.• Can add, delete, modify elements within your database

thru PHP.• Access cookies variables and set cookies.• Can restrict users to access some pages of website.• Can encrypt data.

Where it is used..?

• E-Commerce• Project Management Tools• Graphical User Interface• Building an Online Community• Developing Facebook Applications• Generating PDF Files• Mailing Lists• Image Processing and Generation

History of PHPHistory of PHP• PHP began in 1995 when Rasmus Lerdorf developed a

Perl/CGI script toolset he called the Personal Home Page or PHP• PHP 2 released 1997 (PHP now stands for Hypertext

Processor). Lerdorf developed it further, using C instead• PHP3 released in 1998 (50,000 users)• PHP4 released in 2000 (3.6 million domains). Considered

debut of functional language and including Perl parsing, with other major features• PHP5.0.0 released July 13, 2004 (113 libraries>1,000

functions with extensive object-oriented programming)• PHP 6 is yet to released

Implementations• The PHP language was originally implemented as an interpreter• Several compilers have been developed which decouple the

PHP language from the interpreter.• Advantages of compilation include better execution speed,

static analysis, and improved interoperability with code written in other languages.

• Phalanger, which compiles PHP into Common Intermediate Language (CIL) byte code, and HipHop, developed at Facebook and now available as open source, which transforms the PHP Script into C++, then compiles it, reducing server load up to 50%

• PHP scripts can also be deployed in executable format using a PHP compiler.

Basics

Basic applications• Structurally similar to C/C++• Supports procedural and object-oriented paradigm (to

some degree)• Scripting delimiters• <? php ?>• Must enclose all script code

• Variables preceded by $ symbol• Case-sensitive

• End statements with semicolon• Comments• // for single line• /* */ for multiline

• Filenames end with .php by convention

13

PHP Operators

•Operators are used to operate on values. There are four classifications of operators:

• Arithmetic• Assignment• Comparison• Logical

PHP Arrays

In PHP, there are three kind of arrays:• Numeric array • Associative array• Multidimensional array

Control Structures

• Wide Variety available• if, else, elseif• while, do-while• for, foreach• break, continue, switch• require, include, require_once, include_once

PHP Hello World

•Above is the PHP source code.

PHP Hello World

•It renders as HTML that looks like this:

Security issues

• About 30% of all vulnerabilities listed on the National Vulnerability Database are linked to PHP.

• These are caused mostly by not following best practice programming rules; technical security flaws of the language itself or of its core libraries are not frequent (23 in 2008, about 1% of the total).

• Recognizing that programmers make mistakes, some languages include taint checking to automatically detect the lack of input validation which induces many issues.

Conclusion