CHAPTER 5 SERVER SIDE SCRIPTING -...

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http://fsktm2.uthm.edu.my/azizulzamri CHAPTER 5 SERVER SIDE SCRIPTING PART 1 OF 3 Azizulzamri bin Muhamed Amin [Principles | Operation & Expression | Output]

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CHAPTER 5

SERVER SIDE SCRIPTING

PART 1 OF 3

Azizulzamri bin Muhamed Amin

[Principles | Operation & Expression | Output]

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SERVER SIDE SCRIPTING

The scripts can be written in any of a number of server-side scripting

languages available (Example : PHP, ASP.NET).

Server-side scripting differs from client-side scripting which are run client-

side in the web browser.

Server side code is used to retrieve and generate content for the dynamic

pages (Example : to retrieve the content from database).

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SERVER SIDE SCRIPTING

1) The user requests a web page from the web server.

2) The web server executes the code (no PHP code ever reaches the user) in

the web page and generates an HTML content for that page.

Note :

the code is called "server side code/script" because it is executed by the

web server.

the page containing the code is called dynamic page

3) Information it outputs (the html content) is sent back to the browser so that

it can be displayed to the user.

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SERVER SIDE SCRIPTING

Note:

By the time the data get's to the user's browser, there is no PHP code left, only

the HTML code remains.

That's why if attempt to run your PHP documents on a computer with no web

server will only display the code instead of its output.

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User requests a web page from the web server

Web server executes the code and generate

HTML content

Output sent back to the

client browser

Ex : Hello welcome to my

shop.com

HOW SERVER SIDE SCRIPTS WORK?

Ex :

http://www. myshop.com

Ex : <?php

echo (“Hello welcome to

my shop.com!”);

?>

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Differences of Scripting Lang.

SERVER SIDE SCRIPTING CLIENT SIDE SCRIPTING

PLATFORM Web server Web browser

EXECUTION Before page load After page load

SOURCE CODE Unseen Visible

NEED FOR SERVER Yes No

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BASIC SYNTAX

PHP stands for Hypertext Preprocessor and is a server-side language.

The script is run on your web server, not on the user's browser

PHP is relatively new (compared to languages such as Java) but is quickly

becoming one of the most popular scripting languages on the internet.

PHP scripts are always enclosed in between two PHP tags.

This tags tells the web server to parse the information between the tags as

PHP.

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BASIC SYNTAX

Following are different style for writing PHP script:

1) Everything between the <?php and ?> is read as PHP code.

2) The statement can also be phrased as simply <? if desired.

Anything outside of these PHP tags is read as HTML, hence we can easily

switch between PHP and HTML as needed.

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BASIC SYNTAX

The three different forms are as follows:

Style 1 <?php

PHP Code In Here

?>

Style 2 <?

PHP Code In Here

?>

Style 3 <script language="php">

PHP Code In Here

</script>

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BASIC SYNTAX

There are two ways to use HTML on PHP page.

1) The first way is to put the HTML outside of PHP tags.

<?php -and- ?> are put it in the middle HTML.

2) The second way to use HTML with PHP is by using PRINT or ECHO.

This method you include the HTML inside of the PHP tags.

Each code line in PHP must end with a semicolon. The semicolon is a

separator and is used to distinguish one set of instructions from another.

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BASIC SYNTAX – Style 1

<html>

<body>

<?php

//your php code here

?>

<b>Here is some more HTML</b>

<?php

//more php code

?>

</body>

</html>

Example :

<html>

<body>

<?php

echo("Hello World!“);

?>

<h1>My first PHP page</h1>

<?php

echo(“Good Morning!“);

?>

</body>

</html>

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BASIC SYNTAX – Style 2

Example :

<?php

echo("<html>“);

echo("<title>Style 2</title>“);

echo("<body>“);

echo("<b>My Example</b>“);

print("<i>Hello!</i>“);

echo("<body>“);

echo("</html>“);

?>

This is a nice

quick method if

you only have a

line or so to do.

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echo / echo()

The echo() function outputs one or more strings.

Note: The echo() function is not actually a function, so you are not required to use parentheses with it. However, if you want to pass more than one parameter to echo(), using parentheses will generate a parse error.

Tip: The echo() function is slightly faster than print().

Tip: The echo() function also has a shortcut syntax. Prior to PHP 5.4.0, this syntax only works with the short_open_tag configuration setting enabled.

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Example

In PHP there are two basic ways to get output: echo and print.

echo(strings)

The differences are small: echo has no return value while print has a return value of 1 so it can

be used in expressions. echo can take multiple parameters (although such usage is rare) while

print can take one argument. echo is marginally faster than print.

The echo statement can be used with or without parentheses: echo or echo().

Parameter Description

strings Required. One or more strings to

be sent to the output

<!DOCTYPE html>

<html>

<body>

<?php

echo "<h2>PHP is Fun!</h2>";

echo "Hello world!<br>";

echo "I'm about to learn PHP!<br>";

echo "This ", "string ", "was ", "made ", "with multiple

parameters.";

?>

</body>

</html>

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Print / print()

<!DOCTYPE html> <html> <body> <?php print "<h2>PHP is Fun!</h2>"; print "Hello world!<br>"; print "I'm about to learn PHP!"; ?> </body> </html>

The print statement can be used with or without parentheses: print or print().

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Index , form , print data

1. Index.php

<!DOCTYPE html>

<html>

<body>

<h1>My first PHP page</h1>

<?php

echo "Hello World!";

?>

</body>

</html> 2. form

<form action="action.php" method="post"> <p>Your name:

<input type="text" name="name" /></p> <p>Your age:

<input type="text" name="age" /></p> <p><input

type="submit" /></p> </form>

3. Print data from form

Hi <?php echo htmlspecialchars($_POST['name']); ?>.

You are <?php echo (int)$_POST['age']; ?> years old.

.

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BASIC SYNTAX - COMMENT

A comment is the portion of a program that exists only for the human

reader and stripped out before displaying the programs result.

All text that appears between the start of the comment and the end will be

ignored.

There are two commenting formats in PHP:

1) Single-line comments:

generally used for single line comments (short explanations of code).

2) Multi-lines comments:

generally used to provide more detailed explanations (go over one

line) when necessary.

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BASIC SYNTAX - COMMENT

A single line comment is written as follows:

// Your comment can go in here

Everything after the // will be ignored when the script is executed.

Single line comment can also be placed on the end of a statement.

Example:

print("Hello $name“); // Welcome to the user

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BASIC SYNTAX - COMMENT

The multiline style of commenting is the same as in C.

A multiline comment is written as follows:

/*

The following piece of code will take the input

the user gave and will check that it is valid before

adding it to the database

*/

Anything between the /* and the */ will be ignored.

It is important to always close this type of comment as not doing so could

make the script not working.

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BASIC SYNTAX - COMMENT

Example :

<?php

echo("Hello World!“); // example of single line comment

/*

This echo statement will print out

a hello world message

*/

echo("Hello World!“);

?>

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BASIC SYNTAX - variable

As with other programming languages, PHP allows you to define variables.

All variable begin with a $ sign.

In PHP there are several variable types, but the most common is called a

string.

Variables can hold text and numbers.

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BASIC SYNTAX - variable

To assign some text to a string you would use the following code:

$welcome_text = "Hello and welcome to my website.";

Variables are case sensetive so $Welcome_Text is not the same as $welcome_text

When assigning numbers to variables you do not need to include the quotes so:

$user_id = 987;

would be allowed.

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BASIC SYNTAX - variable

Rules for PHP variables:

A variable starts with the $ sign, followed by the name of the variable

A variable name must begin with a letter or the underscore character

A variable name can only contain alpha-numeric characters and

underscores (A-z, 0-9, and _ )

A variable name should not contain spaces

Variable names are case sensitive ($y and $Y are two different

variables)

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OPERATION AND EXPRESSION

Expressions are used to perform operations and give an answer to a single

value.

Expressions consist of two parts : operators and operands.

Operands can be:

1) Variables

2) Numbers

3) Strings

4) Boolean values

5) other expressions.

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OPERATION AND EXPRESSION

a = 3 + 4

b = (3 + 4) / 2

expression (3+4) is used as an

operand along with b and 2

Example 1: Example 2:

operands operands operators operators

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OPERATION AND EXPRESSION

Operators are used perform operations on operands (variables and

values).

Following are major categories of operator supported by PHP.

1) Arithmetic Operators

2) Comparison Operators

3) Logical Operators

4) Assignment Operators

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OPERATION AND EXPRESSION

Arithmetic operators apply mathematical functions to the operands.

Operator Name Description Example Result

+ Addition Sum of x and y

Example : x + y 2 + 2 4

- Subtraction Subtract of x and y

Example : x - y 5 - 2 3

* Multiplication Multiplication of x and y

Example : x * y 5 * 2 10

/ Division Division of x and y

Example : x / y 15 / 5 3

% Modulus Remainder of x divided by y

Example : x % y 5 % 2

10 % 8

10 % 2

1

2

0

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

<?php

$a = 42;

$b = 20;

$c = $a + $b;

echo("Addition Operation Result: $c“);

$c = $a - $b;

echo("Subtraction Operation Result: $c“);

$c = $a * $b;

echo("Multiplication Operation Result: $c“);

?>

Output :

Addition Operation Result: 62

Subtraction Operation Result: 22

Multiplication Operation Result: 840

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

Comparison operator compare one operand to another operand.

Comparison operators are used inside conditional statements and evaluate

to either true or false.

They give the ability to compare whether elements are equal, identical, less

than or greater than one another (with some other variations).

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

Operator Name Description Example Result

== Equal True if x is equal to y

Example : x == y 5==8

FALSE

!=

<>

!==

Not equal True if x is not equal to y or

they are not of same type

Example : x != y or x <> y or x !== y

5!=8

5<>8

5!=="5"

TRUE

> Greater than True if x is greater than y

Example : x > y 5>8

FALSE

< Less than True if x is less than y

Example : x < y 5<8

TRUE

>= Greater than

or equal to

True if x is greater than or

equal to y

Example : x >= y

5>=8 FALSE

<= Less than or

equal to

True if x is less than or

equal to y

Example : x <= y

5<=8 TRUE

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

<?php

$a = 42;

$b = 20;

if($a==$b)

{

echo("TEST1 : a is equal to b“);

}

else

{

echo("TEST1 : a is not equal to b“);

}

?> Output :

TEST1 : a is not equal to b

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

Logical operators compare elements using comparisons AND, OR, and the

LIKE.

Operator Name Description Example Result

&& AND True if both x and y are

true

Example : x && y

x=6 ,y=3

(x < 10 && y > 1)

TRUE

|| OR True if either or both x

and y are true

Example : x || y

x=6 , y=3

(x==5 || y==5)

FALSE

! NOT True if x is not true

Example : !x x=6, y=3

!(x==y)

TRUE

XOR XOR True if either x or y is

true, but not both

Example : x xor y

x=6 ,y=3

(x==6 xor y==3)

FALSE

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

<?php

$a = 42;

$b = 0;

if($a<10 && $b>1)

{

echo("TEST1 : Both a and b are true“);

}

else

{

echo("TEST1 : Both or either a or b is false);

}

?> Output :

TEST1 : Both or either a or b is false

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

The assignment operator is used to assign values to variables in PHP.

Such an assignment of value is done with the "=", or equal character.

Operator Name Description

++ x Pre-increment Increments x by one, then returns x

x ++ Post-increment Returns x, then increments x by one

-- x Pre-decrement Decrements x by one, then returns x

x -- Post-decrement Returns x, then decrements x by one

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

Assignment Details Description Example Result

x = y x = y The left operand gets set to

the value of the expression

on the right

x=6, y=3

x = y

x=3

y=3

x += y x = x + y Addition x=6, y=3

x += y

x=9

y=3

x -= y x = x - y Subtraction x=6, y=3

x -= y

x=3

y=3

x *= y x = x * y Multiplication x=6, y=3

x *= y

x=18

y=3

x /= y x = x / y Division x=6, y=3

x /= y

x=2

y=3

x %= y x = x % y Modulus x=6, y=3

x %= y

x=0

y=3

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OPERATION AND EXPRESSION

<?php

$a = 42;

$b = 20;

/* Assignment operator */

$c = $a + $b;

echo("Addition Operation Result: $c“);

/* c value was 42 + 20 = 62 */

$c += $a;

echo("Add AND Assignment Operation Result: $c“);

?> Output :

Addition Operation Result: 62

Add AND Assignment Operation Result: 104

ARITHMETIC | COMPARISON| LOGICAL| ASSIGNMENT

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OUTPUT

There are 4 different ways of outputting text to the browser:

1) echo("Text here");

2) echo "Text here";

3) print("Text here");

4) print "Text here";

All of these do the same thing where the information to be printed is

contained between the quotation mark.

However, aapparently in very large programs that are simply outputting

text, the ECHO statement will run slightly faster.

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OUTPUT

Example:

<?php

echo("Hello World");

echo “Hello World";

print("Hello World");

print "Hello World";

?>

Echo and print commands can prints either a string variable or quotes.

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OUTPUT – outputting string

Echo and print uses quotes to define the beginning and end of the string.

Hence, to use a quotation mark inside echo or print, the escape character; a

backslash (\) must be used:

The backslash will tell PHP that the quotations are to be used within the

string and NOT to be used to end echo's string.

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OUTPUT – outputting string

Example :

<?php

// This won't work because of the quotes around specialH5!

echo "<h5 class="specialH5">Hello World!</h5>";

// OK because we escaped the quotes!

echo "<h5 class=\"specialH5\">Hello World!</h5>";

// OK because use of apostrophe ‘ instead

echo "<h5 class='specialH5'>Hello World!</h5>";

?>

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OUTPUT – outputting variable

To output variable values, no quotations are required, even if the variable

hold a string.

Example :

<?php

$my_string = "Hello, my name is: ";

$my_number = 4;

$my_letter = a;

echo $my_string;

echo $my_number;

echo $my_letter;

?>

Output :

Hello, my name is: 4a

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OUTPUT – outputting variable & text

Outputting variables can also be done by placing the variable inside of

double-quoted strings (e.g. "string here and a $variable").

Putting a variable inside the quotes (" ") tells PHP to take the string value of

that variable and use it in the string.

Example:

<?php

$my_string = "Hello, my name is: ";

echo "$my_string Bob";

?>

Output :

Hello, my name is: Bob