Website Development PHP Roundup. PHP Basics This presentation covers the key features of PHP without getting into the way we use it in collaboration with

Website Development

PHP Roundup

PHP Basics

This presentation covers the key features of PHP without getting into the way we use it in collaboration with MySQL

Early in semester two there will be an online quiz covering the material presented here.

The questions will be mainly multiple choice.

You will complete the quiz as an in-class test.

It will contribute 10% towards the coursework marks.

TopicsWhat is PHP?

How does it work? What does a PHP script look like? Passing data to and from PHP

Programming with PHP Variables, Loops, Conditionals,

Arrays, Functions etc.

What is PHP?PHP Hypertext Pre-processor

Project started in 1995 by Rasmus Lerdorf as "Personal Home Page Tools"

Taken on by Zeev Suraski & Andi Gutmans

Current version PHP 5 using Zend 2 engine (from authors names)

Very popular web server scripting application Cross platform & open source Built for web server interaction

Popularity of PHP

www.php.net/usage.php

How does it work? PHP scripts are called via an incoming HTTP request

from a web client Server passes the information from the request to PHP

The PHP script runs and passes web output back via the web server as the HTTP response

Extra functionality can include file writing, db queries, emails etc.

HTMLHTML

HTTP

Web serverClient

What does a PHP script look like?

A text file (extension .php) Contains a mixture of content and programming

instructions Server runs the script and processes delimited blocks

of PHP code Text (including HTML) outside of the script delimiters

is passed directly to the output e.g.<html><head><title>Simple PHP</title></head><body> <? for ($i=0; $i<10; $i++) { print("Hello World!! "); } ?></body></html>

Code inside <? ... ?> delimiters(or <?php ... ?>)

Programming with PHPPHP uses common language structures

Similar syntax to Perl, JavaScript etc

PHP is interpreted (not compiled) No special tools needed

Each programming statement must end with a semi-colon e.g. <?

$name="Paul"; print("$name");?>

VariablesPlaceholders to store data values

Strings (text), numbers, Boolean (true/false) etc No need to declare type or name before use

$myname = "Paul";

$myAge = 21;

Variable names are case-sensitive

All variable names start with a dollar sign $

String values assigned in quotes

OperatorsOperator Performs Example Output

+ Addition print(2+2); 4

- Subtraction print(10-4); 6

* Multiplication print(4*2); 8

/ Division print(12/4); 3

% Modulus print(12%5); 2

++ Increment $value = 10;

print(++$value);

11

-- Decrement $value = 10;

print(--$value);

9

Evaluation ExpressionsExpression Performs Example Output

< Less than if(2<4){

print("ok");}ok(returned true)

> Greater than if(2>4){

print("ok");}

Nothing(returned false)

<= Less than or equal to

if(4<=4){


>= Greater than or equal to

if(2>=2){


== Equal to if(2==4){

print("ok");}

Nothing(returned false)

!= Not equal to if(2!=4){


Loops3 basic ways for repeating code statements

For Execute for a defined

number of repetitions

While If condition is true,

run code and check again. Stop when condition fails

Do While Execute code once, then

check if condition is true. If not, run code again

for ($i=0; $i<10; $i++){ print("Hello World"); }

while ($age < 18) { print("Try again son"); }

do { print("Please log in"); }while ($loggedIn == "no");

Conditional StatementsUsed to evaluate a condition

and act on the outcome if

Condition returns true or false. Use with else to offer alternative

switchCheck against a seriesof possible outcomes

if ($stockLevel<$numRequired){ print("Try ordering less"); }else{ print("Now you can pay!"); }

switch($loggedIn){ case "Yes": print("Welcome!"); break; case "Failed": print("Please try again"); break; default: print("Please login");}

Single or multi-dimensional data structure for storing related values

Built-in arrays used to collect web data $_GET, $_POST etc.

Many different ways to manipulate arrays You will need to master some of them

Arrays

$cars = array("Ford","Reliant","Toyota","Chrysler");

Index/Key 0 1 2 3

Ford Reliant Toyota Chrysler

Array

$cars ……..

Accessing Array DataBy key/index

Loop through

Use print_r()

<?=$cars[0]; ?> Ford

for ($i=0; $i<sizeof($cars); $i++){ print("$cars[$i]");}

FordReliantToyotaChrysler

print_r($cars);

Array ( [0] => Ford [1] => Reliant [2] => Toyota [3] => Chrysler )

FunctionsNamed blocks of re-usable code called when

needed

function welcomeTo($thisUser){

if($loggedIn == "Yes"){ $outPut = "Welcome $thisUser"; } else { $outPut = "Sorry $thisUser is not logged in"; } return $output;

}

... ...

<?=welcomeTo("Dave"); ?>

Function name Input parameter

Function called by name

Return statement

Statements to run

Built-in FunctionsPHP has hundreds of predefined functions

ready to use e.g. String manipulation

e.g. Change "Hello World" to "Hello Springfield"

Mathematical functions e.g. Print the square root of 25

Date and time functions (can get complex) e.g.

www.php.net/manual/en/funcref.php

$text = str_replace("World","Springfield","Hello World");

print(sqrt(25));

print (date("l jS F Y"));

Monday 3rd December 2007

Handling Text StringsStrings can be double or single quoted

Single quoted strings – simplest Escape characters needed, variables must be

concatenated

Double quoted strings More versatile, can include more special characters,

variables can be parsed and expanded

$thisUser = "Dave";

print('The username '.$thisUser.' isn\'t on the list');

$thisUser = "Dave";

print("The username $thisUser isn't on the list");

Passing data to a PHP scriptA PHP script can receive data from the HTTP

request that called it via either GET or POST Includes data supplied by web forms

The script can also extract data from the server environment at run-time

e.g. dates, filenames, IP addresses etc.

Once running a script can also access data from many other sources

e.g. databases, text files, XML documents etc.

A PHP script does not need to have data passed to it in order to run

Output from PHP scriptsBy default output is returned to the web server

as the response to the initial HTTP request Content outside delimiters returned automatically

Other output is programmatically returned e.g. via the echo statement or print() function

A PHP script can also output data to other locations

e.g. databases, text files, XML documents, graphics formats etc

print("server side scripting");

echo "Hello";

Further TopicsPHP and the web environment

Superglobal variables HTTP input (GET and POST) Environment variables phpinfo()

Persistent information Session variables

Working with date and time

Superglobal VariablesEvery PHP script has automatic access to a

range of values at run-time e.g. Web request information

Collected from the HTTP headers e.g. from input, remote IP address etc.

Info about the PHP/server environment Generated at run-time e.g. date/time, file system info

Stored in pre-defined arrays – initially most important are:

$_GET $_POST $_SERVER

$_GETEvery HTTP request is a GETGET can also be used to pass data to server

in querystring Name/Value pairs appended to URL requested Hard coded /generated from HTML form input

PHP puts data into superglobal array $_GET

$_POSTExtra data can be sent as an HTTP POST

Name/Value pairs passed in request body Only generated from HTML form input

PHP puts data into superglobal array $_POST

$_SERVERArray generated by the server at run time

Request information from HTTP headers Referrer, accept headers, user agent info etc.

Server environment data IP address, file/script names & paths etc

Access by name or iteration e.g.$possBrowser = $_SERVER['HTTP_USER_AGENT'];

foreach ($_SERVER as $key => $value) { print("$key $value \n"; }

phpinfo()Exact makeup of PHP environment depends

on local setup & configurationBuilt-in function phpinfo() will return the

current set up Not for use in scripts

Useful for diagnostic work & administration May tell you why something isn't available on

your server

print(phpinfo());

Persistent InformationWeb requests are stateless and anonymous

Information cannot be carried from page-to-page

Client-side cookies can be used Not everyone will accept them

Server-side session variables offer an alternative

Temporarily store data during a user visit/transaction

Access/change at any point

PHP handles both

Session VariablesNot automatically created

Script needs to start session using session_start()

Data stored/accessed via superglobal array $_SESSION

Data can be accessed from any PHP script during the session

session_start();$_SESSION['yourName'] = "Paul";

Script1: Start session and set value

print("Hello $_SESSION['yourName']");

Script 2: Access session and retrieve value

Date and TimeBuilt-in functions to extract, format and

calculate dates & times – can be trickyFirst step usually to obtain the current date

using getdate()

Returns array with current date/time info

Other date/time functions for format and display e.g.

$currDate = getdate();

date("l dS of F Y h:i:s A");

Monday 3rd of December 2007 09:51:38 AM

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Website Development PHP Roundup. PHP Basics This presentation covers the key features of PHP without getting into the way we use it in collaboration with