Introduction to PHP

Introduction to PHP Jussi Pohjolainen TAMK University of Applied Sciences

WEB PROGRAMMING CONCEPTS

Three-tiered Web Site: LAMP Client User-agent: Firefox Server Apache HTTP Server example request GET / HTTP/1.1 Host: www.tamk.fi User-Agent: Mozilla/5.0 (Mac..) ... response Database MySQL PHP

Java EE Architecture (x)html / xml Applet Client Application J2EE Application Server Web Container Servlets JSP JSPs Servlets EJB Container RMI/IIOP JNDI JTA JDBC JMS JavaMail JAF Session Beans Entity Beans Msg-Driven Beans RMI/IIOP JNDI JTA JDBC JMS JavaMai l JAF HTTP(S) JDBC JavaMail RMI IIOP JNDI JMS DB Java-Application CORBA Server Message Queue Directory Service Client Mail Server

Server Side Techniques

Server side scripting requires installation on the server side

Typically client siis only xhtml and it unaware that the xhtml was produced by a server side script

Does not require any installations or add-ons on the client

Server Side Techniques

PHP

Java EE: Servlet, JSP

.NET

CGI / Perl (Very old)

Ruby

…

Client Side Techniques

Requires that the client supports the technique

JavaScript, Applet, Flash…

Web Application Frameworks

A web application framework is a software framework that is designed to support the development of dynamic websites, Web applications and Web services.

Numerous frameworks available for many languages

Web App vs. Web Site?

What’s the difference between Web App and Web Site?

Rich Internet Application?, AJAX?, Thin Client?

Full application running in your browser or just a web site?

PHP: HYPERTEXT PREPROCESSOR

Introduction to PHP

PHP is a computer scripting language.

Originally designed for producing dynamic web pages

Appeared in 1995

PHP Group is responsible for the language, no formal specification

Free software

Runs on most operating systems and platforms

URL: http://www.php.net

Response

Introduction to PHP Syntax

PHP has quite easy syntax, if you are familiar with any c-type language

It has all the same structures that you are familiar with other programming languages

PHP is designed to output to browser, but it is possible to do also CLI apps.

Example

<?php

print "What is your name? ";

$name = trim(fgets(STDIN));

print "Hello " . $name;

?>

Variables

Variables in PHP are represented by a dollar sign

PHP supports eight types:

boolean, integer, float, double, array, object, resource and NULL

Example (php.net)

<?php

$a_bool = TRUE; // a boolean

$a_str = "foo"; // a string

$a_str2 = 'foo'; // a string

$an_int = 12; // an integer

echo gettype($a_bool); // prints out: boolean

echo gettype($a_str); // prints out: string

// If this is an integer, increment it by four

if (is_int($an_int)) {

$an_int += 4;

}

// If $bool is a string, print it out

// (does not print out anything)

if (is_string($a_bool)) {

echo "String: $a_bool";

}

?>

Naming Variables

Case-sensitivity

Start with letter or _

After that you can have numbers, letters and _

$var = 'Bob';

$Var = 'Joe';

print "$var, $Var";

$4site = 'not yet';

$_4site = 'not yet';

Constants

You cannot alter the value of constant after declaration

define(CONSTANT, "value");

print CONSTANT;

Magic Constants

PHP has lot of predefined variables

Also predefined constants:

__LINE__

__FILE__

__FUNCTION__

__CLASS__

__METHOD__

See: http://fi.php.net/manual/en/language.constants.predefined.php

Scope

<?php

$a = "Pekka";

print ”My name is " . $a;

?>

Scope

<?php

$a = "Pekka";

function Test() {

print $a;

}

print ”My name is ”;

Test();

?>

Scope

<?php

$a = "Pekka";

function Test() {

global $a;

print $a;

}

print ”My name is ”;

Test();

?>

Control Structures

If, else, elseif, switch

while, do-while, for

foreach

break, continue

PHP BASICS

Strings

Single quoted: 'this is a $variable'

Double quoted: "this is a $variable"

Heredoc:

$str = <<<EOD

Example of string

spanning multiple lines

using heredoc syntax.

EOD;

Modifying the String

$mj = "moi";

print $mj[0];

$mj[0] = 'x';

print $mj;

$mj = $mj . " hei";

print $mj;

$mj .= " terse";

print $mj;

String functions

A lot of functions…

http://www.php.net/manual/en/ref.strings.php

Statements

Every statement ends with ;

$a = 5;

$a = function();

$a = ($b = 5);

$a++; ++$a;

$a += 3;

Operators

Arithmethic: +,-,*,%

Setting variable: =

Bit: &, |, ^, ~, <<, >>

Comparison: ==, ===, !=, !==, <, > <=, >=

Ternary Operator

$variable = (1 < $x) ? 'value1' : 'value2';

Equals

if(1 < $x) {

$variable = 'value1';

}

else {

$variable = 'value1';

}

Execution Operator

Execute command in shell

$result = `ls -al`;

print $result;

Does the same than shell_exec() - function

Logical Operators

$a and $b

$a or $b

$a xor $b

!$a;

$a && $b;

$a || $b;

String Operators

Two operators for strings: '.' and '.='

'.' – combining strings.

'.=' – appends string to the end.

Example:

$v= "Hello" . $b;

$v.= "Hello";

Arrays

See

http://php.tpu.fi/~pohjus/lectures/php/php-arrays.html

CONTROL STRUCTURES

IF

<?php

if ($a > $b) {

echo "a is bigger than b";

} else {

echo "a is NOT bigger than b";

}

if ($a > $b) {

echo "a is bigger than b";

} elseif ($a == $b) {

echo "a is equal to b";

} else {

echo "a is smaller than b";

}

?>

While and Do-While

<?php

$a=0;

while($a<10){

print $a; $a++;

}

$i = 0;

do {

print $i;

} while ($i > 0);

?>

For

for ($i = 1; $i <= 10; $i++) {

print $i;

}

Foreach

$arr = array(1, 2, 3, 4);

foreach ($arr as $value) {

echo $value;

}

Switch

switch ($i) {

case 0:

echo "i equals 0";

break;

case 1:

echo "i equals 1";

break;

case 2:

echo "i equals 2";

break;

}

PHP COMBINED WITH XHTML

Response

Example: spaghetti-way

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<title>xhtml-doku</title>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

</head>

<body>

<h1>Title</h1>

<?php

print "<p>Hello from PHP!</p>";

?>

</body>

</html>

Better ways

Use functions

Use OO

PHP AND USER INPUT

PHP and User Input via Forms

See

http://php.tpu.fi/~pohjus/lectures/php/forms-and-php.html

Introduction to PHP

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