web programming using php

7/21/2019 Web Programming Using Php

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WEB PROGRAMMING

USING PHP

Rameela Ravindran K

Department of Computer Science

St. Thomas College, Thrissur


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INTRODUCTION TO PHP

Web development language

stands for :-Hypertext Preprocessor

server-side scripting language- can be embedded inHTMLons to love

Reasons to love PhpCost

Open source softwarePhp license

Ease of use (easy to learn and write :- a little bit ofexperience in a C-syntaxed programming language andlittle more involved than HTML

Html embedness (ordinary HTML pages that

escape into PHP mode only when necessary)


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Cross-platform compatibility (Apahe unix, iiswindows, Netscape Enterprise Server)

Not tag based

StabilityServer need not be rebooted oftenSoftware doesn't change radically

Speed (compared to Jsp CGI)

Many extensions (supports ODBC, SQL, access etc:-supports major protocols also)

Fast feature development

team will accept every random contribution into the

official distribution without community buy-in, butindependent developers can and do distribute theirown extensions which may be

later folded into the main PHP package in more orless unitary form.


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Popularity

Not proprietary (not tied to any one serveroperating)


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SERVER SIDE WEB SCRIPTING

On the client, it can mean multimediapresentations, scrolling headlines, pages thatupdate themselves automatically, or elements thatappear and disappear. On the server, the termgenerally denotes content assembledon the fly, at

the time the page is requested. If you displaythecurrent date and time on a page, for example, thecontent will change from one occasion to anotherand thus will be dynamic.

Client-Sideanything to do with layout or browser events happens onthe client

client-side technologies cannot do anything that requiresconnecting to a back end server. JavaScript cannot

assemble a customized drop-down list on the fly fromuser preferences stored in a database


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Server-side Web scripting is mostly aboutconnecting Web sites to back end servers, such asdatabases. This enables the following types oftwo-way communication:Server to client: Web pages can be assembled

from back end-server output

Client to server: Customer-entered information

can be acted upon.

Common examples of client-to-server interactionare online forms with some drop-down lists


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handle many of the crucial technical andadministrative details necessary to keep a siterunning, such as:HardwareSoftware upgradesInterNIC registration, IP addressing, DNSMail servers (POP/IMAP and SMTP)Bandwidth

Power supplyBackupsSecurity


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INSTALLING PHP

A server or workstation with enough RAM for OS

Unix, Mac OS X, or Windows operating system

Working, dedicated Internet connection

Install PHP on Windows:Working PHP-supported Web server. Under previousversions of PHP, IIS/PWS was the easiest choicebecause a module version of PHP was available for it;but PHP now has added a much wider selection of

modules for Windows.correctly installed PHP-supported databasePHP Windows binary distributionutility to unzip files


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Extract the binary archive using unzip utility; C:\PHP -common location.

Copy .dll files from PHP directory to systems directory (usually

C:\Winnt\System32). php5ts.dll , Web server moduleC:\PHP\Sapi\php5isapi.dll., dlls subfolder are the necessary to be copied to the system

Copy either php.ini-dist or php.ini-recommended toWindowsdirectory (C:\Winnt or C:\Winnt40), and rename it php.ini. Open this file ina text editor. Edit this file to get configuration directives. Set error reportingto E_ALL on their development machines at this point. For now, the mostimportant thing is the doc_root directive under the Paths and Directoriessectionmake sure this matches your IIS Inetpub folder

Stop and restart the WWW service. Go to the Start menu Settings

Control Panel Services. Scroll down the list to IIS Admin Service.Select it and click Stop. After it stops, select World Wide Web PublishingService and click Start. Stopping and restarting the service from withinInternet Service Manager.

5. Open a text editor Type: . Save this file inyourWeb servers document root as info.php. Start any Web browser and browsethe fileyou must always use an HTTP request (http://www.testdomain.com/info.phpor http://localhost/info.php or

http://127.0.0.1/info.php) rather than a filename(C:\inetpub\wwwroot\info.php) for the file to be parsed correctly. Youshould see a long table of information about your new PHP5 installation.
http://www.testdomain.com/info.phphttp://www.testdomain.com/info.php


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BEGINNING WITH PHPCanonical PHP tags

The most universally effective PHP tag style is

Short-open (SGML-style) tags

Short or short-open tags

do one of two things to enable PHP to recognize thetags:Choose the --enable-short-tags configuration optionwhen youre building PHP.

Set the short_open_tag setting in your php.ini file toon.

ASP-style tagsASP-style tags mimic the tags used by Microsoft ActiveServer Pages to delineate code blocks :


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HTML script tags


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SYNTAX AND VARIABLES

PHP syntax is relevant only within PHP

PHPs Syntax Is C-LikePHP is whitespace insensitive

Statements are expressions terminated bysemicolons

$greetings =Welcome to PHP;Expressions are combinations of tokens

Expressions are evaluated

Expressions mathematical, boolean, string,

assignment expressionPrecedence, associatively, and evaluation order


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COMMENTS

Portion of a program that exists only for humanreadersMultiline comments: starts with the characterpair /* and terminates with */

They cannot be nestedSingle line comments: # and // are the commentingto a given line


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VARIABLES

denoted with a leading dollar sign ($).

value of a variable is the value of its most recentassignment.

need not to be declared before assignment.no intrinsic type other than the type of theircurrent value.

have default values.

Variable = value


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After the initial $, variable names must becomposed of letters (uppercase or lowercase),

digits (09), and underscore characters (_).first character after the $ may not be a number.

types are associated with values rather thanvariables

no declaration is necessaryReassigning variables

IsSet that tests a variable to see whether it hasbeen assigned a value.

unset() will restore a variable to an unassignedstate (for example, unset($set_var); will make$set_var into an unbound variable, regardless ofits previous assignments).


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Variable ScopeGlobalLocal

Defined ConstantsDefine(variablename, value);

Pre-defined variables$_GET$_POST

$_COOKIE$_FILES$_ENV$_SESSION


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DATA TYPES

PHP has a total of eight types: .

Integers are whole numbers, without a decimal point, like495. range -231-1 to 231-1

Doubles are floating-point numbers, like 3.14159 or 49.0.

Booleans have only two possible values: TRUE and FALSE.NULL is a special type that only has one value: NULL.

Strings are sequences of characters, like PHP 4.0 supports

string operations.

Arrays are named and indexed collections of other values.

Objects are instances of programmer-defined classes, which

can package up both otherkinds of values and functions thatare specific to the class.

Resources are special variables that hold references to

resources external to PHP (suchas database connections).


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Strings can be enclosed in either single or doublequotation marks, with different behavior at readtime.

Singly quoted strings are treated almost literally,

doubly quoted strings replace variables with theirvalues as well as specially interpreting certaincharacter sequences.


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Output:The two most basic constructs for printing to outputare echo and print

The simplest use of echo is to print a string as

argument, for example:echo This will print in the users browser window.;

Or equivalently:echo(This will print in the users browser window.);

multiple arguments to the unparenthesized version ofecho, separated by commas, as in:

echo This will print in the , users browserwindow.;


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Printprint can accept only one argument.print returns a value, which represents whether theprint statement succeeded.

$animal = antelope;$animal_heads = 1;$animal_legs = 4;print(The $animal has $animal_heads head(s).

);print(the $animal has $animal_legs leg(s).
);


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Break

Continue

Alternate control syntaxes

alternate to start and end if switch for whileconstruct

If(expression) if(expression):

{ statement1

Statement1 statement2

statement2} endif;


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FUNCTION

Function function_name($argument_1,$argument_1)

{

}

Call by valueCall by referenceDefault argumentReturn by value

Function &function_name($argument_1,$argument_1){

Return $variable;

}$variable= &function_name;


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PASSING INFORMATION BETWEENPAGES

Passing variables between pages using URL

Passing variables between pages using Cookies

Passing variables between pages using sessions

PHP will catch the variable tossed from one pageto the next and make it available for further use.PHP happens to be unusually good at this type of

data-passing function, which makes it fast andeasy to employ for a wide variety of Web sitetasks.


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GET ARGUMENTS

The GET method passes arguments from onepage to the next as part of theUniform Resource

Indicator querystring.

When used for form handling, GET appends the

indicated variable name(s) and value(s) to theURL designated in the ACTION attribute with aquestion mark separator and submits the wholething to the processing agent- a Web server


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A GET method example, part 1

Root, root, root for the:

Chicago Cubs (NationalLeague)

Chicago White Sox (AmericanLeague)


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When the user makes a selection and clicks the Submit button,the browser agglutinates these elements in this order, with nospaces between the elements:

The URL in quotes after the word ACTION (http://localhost/baseball.php)

A question mark (?) denoting that the following charactersconstitute a GET string.

A variable NAME, an equal sign, and the matching VALUE(Team=Cubbies)

An ampersand (&) and the next NAME-VALUE pair(Submit=Select); further name-value pairs separated byampersands can be added as many times as the server

querystring-length limit allows. The browser thus constructs the URL string:http://localhost/baseball.php?

Team=Cubbies&Submit=Select

Itth f d thiURLitit dd
http://localhost/baseball.phphttp://localhost/baseball.php


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It then forwards this URL into its own address space as a newrequest. The PHP script to which the preceding form is submitted(baseball.php) will grab the GET variables from the end of therequest string, stuff them into the $_GET superglobal array.

The following code sample shows the PHP form handler for thepreceding HTML form:

A GET method example, part 2

Go,!


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Advantages of GET over POSTIt constructs an actual new and differentiable URL

query string. Users can now bookmark this page. Theresult of forms using the POST method is notbookmarkable.

Disadvantages:

The GET method is not suitable for logins because

the username and password are fully visibleonscreen as well as potentially stored in the clientbrowsers memory as a visited page.

Every GET submission is recorded in the Web server

log, data set included.Because the GET method assigns data to a serverenvironment variable, the length of the URL islimited. (Maximum 300-word chunk of HTML-formatted prose using GET method)


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HTTP POST METHOD


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HTTP COOKIES


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HTTP SESSION


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ARRAY

Create arrayBy assigning a value into one

$my_array= the first thing;

By using array()

$my_array=array();$my_array= array(apple, orange, pear);$my_array[0]= apple;$my_array[1]=pear;$my_array= array(1,1,52,73);

By calling a function that happens to return an arrayas its value

$my_array= range(1,5);$my_array=fun(4);


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RETRIEVING VALUE

IndexEcho $my_array[1];

List()$my_array= array(apple, orange, pear);list($f1,$f2,$f3)=$my_array;


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Deleting from arrayUse unset()

IterationHidden pointer system built into arrayEach index value points to the nextForeach loop

Foreach($a as $v)

traversing using list() and each()

While(list($key,$val)=each($array)


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Array functionsIs_array($myarray)Count($myarray) // nonempty elementsSizeof()

In_array($myarray, a)Isset($myarray[$key] // key is valid or not


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ARRAY OPERATIONS

Union (+)

Equality(==) // same key value pair

Identity (===)// same key value pair in the sameorder and of same type

Inequality (!= )

Non identity (!==)


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ARRAY FUNCTION

Is_array()

Array_fill($startindex,$num,$value)

Array_key_exists($key, $array)

Array_sum($myarray)Array_count_values // array using the values ofthe input as key and their frequency as values

Array_unique()


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Sort(&$my_array[,$sort_flag=______)Sort_regularSort_numeric

sort_string

Asort(&$my_array[,$sort_flag= -------------)

Rsort((&$my_array[,$sort_flag= -------------)

arsort (&$my_array[,$sort_flag= -------------)

ksort (&$my_array[,$sort_flag= -------------) //sortby key

krsort (&$my_array[,$sort_flag= -------------)

natsort (&$my_array[,$sort_flag= -------------)natcasesort (&$my_array[,$sort_flag= -------------)


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In_array($value,$array)

Each($array) // return each key value pair

List()

Current($array) // return current elementNext()

Pre()

End() // sets the pointer to the last element

Reset()count()


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STRINGS IN PHP

Sequence of characters

Accessed using index

concatenation using .

Heredoc syntax


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STRING FUNCTIONS

Strlen($string)

Strops()strpos($mystring,$findme[,offset=0])Mystring string to be searched inFindme item to be searched

Offset which character to start searching$pos= strpos($mystring,$findme)

Strrpos()Postion of the last occurrence of the substring

Stripos()Strripos()

str


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DATABASE

Collection of data with regular and predictablestructure

Examples :postgreSQLMySQLSQL ServerOracle


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MYSQL

Freeware

Stable no crashing

Lightweight require no


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