Unit 5 - PHP - Hello World! - Data types - Control structures - Operators

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4 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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PHP

P
HP

H
ypertext

P
re
-
processor

Unit 6
-

PHP


-

Hello World!

-

Data types

-

Control structures

-

Operators

Why do we need PHP?


Dynamic data
-
driven web sites


Display dynamic information to users


Collect information from users


Examples:


Online shopping site


Web forum


Newspaper site


etc

Options


Perl


Microsoft ASP.NET


JSP


ColdFusion


XSLT


others

PHP Strengths


High Performance


Interfaces with many database systems


Built
-
in libraries


Low cost


Open source


Support


Easy to learn and use

What is PHP?


Server
-
side scripting language


Conceived in 1994


Open Source


Current version is 5


Reference page: http://www.php.net

Book(s)

How it works


Client requests document


Server loads document in memory


Server processes document with
relevant module (PHP)


Server sends XHTML document to
client


Client displays document




Hello World!

Hello World!

<html>

<body>


</body>

</html>


Hello World!

Output

Hello World!

Hello World!

<html>

<body>


</body>

</html>



<?php ?>




echo




'Hello World';

Output 1

<html>

<body>

Hello World

</body>

</html>

Output 2

Hello World

Hello World!

<html>

<body>


<?php echo "<p><i>Hello</i>


<b>World</b></p>" ?>

</body>

</html>


Output 1

<html>

<body>

<p><i>Hello</i> <b>World</b></p>

</body>

</html>

Output 2

Hello

World




PHP Basics

PHP Syntax basics


PHP code embedded in <?php … ?>


Files containing PHP code must have a .php extension (or
php3, etc)


Syntax very similar to C and Java


Statements delimited by ;


Comments as in C/Java:


/* comment */


// comment


But also: # comment


Variables preceded by $, for example:


$x = 2;


$first_name = joe;


More on variables later …





Data Types

Data types


Integer


for whole numbers


Float


for real numbers


String


for strings of characters


Boolean


for true or false values


Array


For collections of data


Object


For OO programming

<?
php





?>



Strings

$first_name = 'John';

$last_name = 'Doe';

echo $first_name;

Output:

John

Strings

<?php





?>



Strings

$first_name = 'John';

$last_name = 'Doe';

echo '$first_name';

Output:

$first_name

Strings

<?php





?>



Strings

$first_name = 'John';

$last_name = 'Doe';

echo "$first_name";

Output:

John

Strings

<?php






?>

Strings

$first_name = 'John';

$last_name = 'Doe';

echo "Your name is:
$first_name $last_name";

Output:

Your name is: John Doe

Strings

Strings

<?php






?>

Strings

$first_name = 'John';

$last_name = 'Doe';

echo "You said:
\
"my name is
$first_name $last_name
\
"";

Output:

Your said: “my name is John Doe”

Strings

Strings

Strings

<?php






?>

Strings

$first_name = 'John';

$last_name = 'Doe';

echo "... And you are worth
\
$2M";


Output:

... And you are worth $2M

Strings

Strings

Strings

Strings

<?php





?>

Strings

$first_name = 'John';

$last_name = 'Doe';

echo $first_name[0];

Output:

J

Strings

Strings

Strings

Strings

Strings

<?php





?>

Strings

$first_name = 'John';

$last_name = 'Doe';

echo substr('abcdef', 1, 4);

Output:

bcde

Strings

Strings

Strings

Strings

Strings

Strings

<?php





?>

Strings

$first_name = 'John';

$last_name = 'Doe';

echo substr($first_name, 0, 6);


Output:

? (guess and write it down)

Strings


No / Single / Double quote


String type:
http://uk.php.net/manual/en/language.types.string.php


Functions available:
http://uk.php.net/strings

Integers and Floats

<?php


$a = 1234;


$b = 12.02;

?>



Integer type:
http://uk.php.net/manual/en/language.types.integer.php


Float type:
http://uk.php.net/manual/en/language.types.float.php


Boolean


Logical operators:


And: &&


Or: ¦¦


Not: !


Boolean type:
http://uk.php.net/manual/en/language.types.boolean.php

Array

id

First Name

Last Name

Job

1

Joe

Smith

Surgeon

2

John

Johnson

Nurse

3

Jack

Jackson

Consultant

4

Jim

Jones

IT

Array


Fundamental data structure in PHP


Used to store collections of values


Multidimensional array: array that
contains arrays.


Different types of arrays:

1.
Numerically indexed arrays

2.
Non
-
numerically indexed arrays

3.
Does it make any difference?

1. Numerically indexed array

<?php


$names =
array
(


);



?>












'Joe',

'John',

'Jack',

'Jim'


echo $names[1];

Output:

John

2. Non
-
numerically indexed
array

<?php


$record =
array
(




?>



firstName => 'John',

lastName => 'Smith');

echo $record[lastName];

Output:

Smith

3. Key
-
value pairs

<?php


$arr =
array
(











);


echo $arr[1];

?>


Output:



0 => 'Joe',

1 => 'John',

2 => 'Jack',

3 => 'Jim'

Multidimensional arrays

<?php


$record =
array
(














);


/* i.e. an array of arrays */


array
(firstName => 'Joe',







lastName => "McDonald"),

array
(firstName => 'John',








lastName => "Smith"),

array
(firstName => 'Jack',





lastName => "Black")

Multidimensional arrays

...

echo $record[1][lastName];

echo '<br/>';

echo $record[1][1];

?>


Output:







Operators

Directed study

http://uk.php.net/manual/en/language.operators.php




Control structures

http://uk.php.net/manual/en/language.control
-
structures.php

if, else, elseif

<?php


$value = 24;









?>

if

($value < 20)



echo “not enough!”;

elseif

($value < 30)



echo “reasonable.”;

elseif

($value < 40)



echo “perfect!”;

else


echo “Too much!”;

switch

<?php

switch

($value){









}?>


case

24:


echo "Correct!";


break;

case

25:


echo "Almost correct!";


break;

default
:


echo "Too much!";

for

<?php


for

( ; ; )
{




}

?>


($i = 1

$i <= 10

$i++

echo $i;

Output:

12345678910

foreach

<?php










?>

$arr = array("one", "two", "three");

echo "Using a for loop:<br />
\
n";


for

($i = 0; $i <
sizeof
($arr); $i++) {


echo "Value: $arr[$i]<br />
\
n";


}

echo "Using a foreach loop:<br />
\
n";


foreach

($arr as $value) {


echo "Value: $value<br />
\
n";


}

while

<?php



$i = 1;

while

($i <= 10) {



echo $i;




i++;


}

Output:

12345678910

Summary


Basics


Data types


Control structures


Operators
-

Directed study:


Arithmetic operators


Comparison operators


Logical operators


String operators

http://uk.php.net/manual/en/language.operators.php

Next week


Tutorial: Introduction to PHP





Lecture: Introduction to MySQL

Rest of the module

Nothing but:


PHP


MySQL


XHTML


CSS