Web Programming Language - PowerPoint Presentation

Slide1

Web Programming Language

Chapter 4

Slide2

Introducing PHP

Setting Up a Web Server

PHP Basic Syntax

PHP Variables

PHP Operators

PHP Flow Control

PHP Form Validation

Slide3

PHP

“Hypertext Pre Processor”

Common Server-side language powering 80% of websites

Core Part of WAMP stack (Windows Apache MySQL PHP)

Or LAMP, or MAMP

Slide4

Set Up A Webserver

If you already have a webserver – great!

If not, set up your local machine as a host, by installing

wampserver

.

Create a file called hello.php

in your www folder

<?php echo “Hello World” ?>

Open it in a browser;

localhost/

hello.php

or 127.0.0.1/

hello.php

Slide5

PHP Variables

Begin with $

Named by any combination of letters, numbers, and _

$Name

Case Sensitive

$NAME, $Name, $name are different variables

Can store different types of data

Strings, Integers, Floats, Boolean, Array & Objects

Weakly Typed

You don’t need to specify which type of data the variable will store

No need for declaration

Slide6

PHP Variables

<?php

$x = 5;

$y = “3.5”;

$z = $x + $y;

echo "The number is $z<

br

>";

echo "The number is " . $z . "<

br

>";

?>

Opening PHP Tag

Concatenation

Closing PHP Tag

Assignment

Addition

Output

Slide7

Arrays

Creates an Indexed array where “John” has index 0, and Fred has index 3.

<?php

$students = array(“John”, “Bob”, “Steve”);

$students[] = “Fred”;

echo “The first student is “ . $students[0];

?>

Slide8

Associative Arrays

The Index could be a string

<?php

$ages = array(“John”=>”18”, “Bob”=>”19”, “Steve”=>”22”);

echo “John is “ . $ages[“John”];

?>

Each element is a “Key=>Value” Pair

Slide9

Multidimensional Arrays

A 2 dimensional array is just an Array of Arrays

<?php

$students = array();

$students[] = array("John", "84", "A");

$students[] = array("Bob", "65", "C+");

$students[] = array("Steve", "72", "B");

echo "The first student's grade is " . $students[0][2];

?>

Slide10

Strings

Strings are important in PHP (we are dealing with text on the web of course!)

Function Name

Purpose

explode()

Splits a string into an array

implode()

Converts an array into a string

lcfirst()

Makes the first character of a string lowercase

str_replace()

Replaces specified characters in a string

str_word_count

()

Returns the number of words in the string

strcmp()

Compares two strings

strlen()

Returns the length of a string

strpos()

Returns the position of the first occurrence of a string inside another string

strtoupper()

Converts a string to upper case

strtolower()

Converts a string to lower case

substr()

Returns a specified part of a string

ucfirst()

Makes the first character of a string uppercase

Slide11

PHP Operators (Arithmetic)

Arithmetic Operators

Purpose

Example

+

Addition

$x=1+2;

-

Subtraction

$x=2-1;

*

Multiplication

$x=1*2;

/

Division

$x=2/1;

%

Modulus Returns the remainder from a division

$x=2%1;

++

Increment (add one to the value)

$x++;

--

Decrement (minus one from the value)

$x--;

Slide12

PHP Operators (Assignment)

Assignment Operators

Example

Equivalent

=

$a = $b;

 

+=

$a += $b;

$a = $a + $b;

-=

$a -= $b;

$a = $a – $b;

*=

$a *= $b;

$a = $a * $b;

/=

$a /= $b;

$a = $a / $b;

%=

$a %= $b;

$a = $a % $b;

.=

$a .= $b

$a = $a . $b;

Slide13

PHP Operators (Logical)

Logical Operators

Purpose

==

Equal to

!=

Not equal to

<> 

Not equal to

< 

Less than

> 

Greater than

<=

Less than or equal to

>=

Greater than or equal to

&&

AND

||

OR

!

Not

Slide14

PHP Flow Control (IF)

<?php

if($x>20)

{

echo “x is greater than 20”;

}

elseif($x<10)

{

echo “x is smaller than 20”;

}

else

{

echo “x is between 10 and 20”;

}?>

Slide15

PHP Flow Control (Switch)

<?php

switch ($x) {

case “login”:

echo “Display the Login Page”;

break;

case “register”:

echo “Display the Register Page”;

break;

default:

echo “Display the Guest Page”;

break;

}

?>

Slide16

PHP Flow Control (While)

<?php

$x = 10;

while($x>0)

{

echo “There were “ . $x . “ in the bed, till someone said, roll over…<

br

>”;

$x--;

}

?>

Slide17

PHP Flow Control (Do…While)

<?php

$x = 10;

do {

echo “There were “ . $x . “ green apples, ready to be eaten…<

br

>”;

$x--;

} while($x>0);

?>

Slide18

PHP Flow Control (For)

<?php

for($

i

= 0; $

i<10; $i

++)

{

echo “I have “ . $

i

. “ doors, but need 1 more…<

br

>”; }

?>

Slide19

PHP Flow Control (Foreach)

<?php

$count = 1;

foreach($students as $name)

{

echo $count . “) Student name:- “ . $name . “<

br

>”;

$count++;

}

?>

Slide20

PHP Flow Control (Foreach) Associative

<?php

$count = 1;

foreach($students as $name => $grade)

{

echo $count . “) Student “ . $name . “ got grade “ . $grade . “<

br

>”;

$count++;

}

?>

Slide21

PHP Form Validation

HTML’s <form> tag is used to create a form that can send data to the server.

<form action="

welcome.php

" method="post">

Name: <input type="text" name="name"><

br

/>

<input type="submit" value="Go!">

</form>

Slide22

$_POST

The previous form sends data by the POST method to

welcome.php

<body>

Welcome <?php echo $_POST[“name”]; ?>

</body>

Slide23

$_GET

An alternative is to send the data via the GET method

<form action="

welcome.php

" method="get">

Name: <input type="text" name="name"><

br

/>

<input type="submit" value="Go!">

</form>

<body>

Welcome <?php echo $_GET[“name”]; ?>

</body>

What is the difference?

Slide24

$_POST or $_GET

Both arrays are

Superglobals

, accessible from any function, class or file on the page.

Both create an array of key=>value pairs with the names of the form inputs and the values submitted

The GET method passes variables via URL parameters, while POST passes it via HTTP Post method.

The GET method is visible, so should not be used for sensitive data, but because it is visible, it can be bookmarked. However the URL is limited to around 2,000 characters.

Slide25

print_r

()

A useful function for making a human readable version of an array

<body>

<?php

print_r

($_POST); ?>

</body>

Slide26

Simple Form Validation

<body>

<?php

$name = $_POST["name"];

if(

strlen

($name)<3)

{

echo "Name must be at least 3 characters.";

}

?>

</body>

Slide27

Key Points

PHP is an important Server Side programming language.

Before running PHP code a web server needs to be set up to process PHP code.

When a web server receives a request for PHP, first it processes the code before returning HTML.

Variables in PHP are weakly or loosely typed and can also be used to store arrays.

A form can be used to send data to the server using the post method.

Data sent via the post method then exists within the $_POST

superglobal

array, or using the get method to the $_GET

superglobal

array.

The main difference between post and get is that when using get, the parameters are attached to the

url

, so that it can be bookmarked.