The document discusses server-side scripting. It explains that server-side scripting languages like PHP, ASP, ASP.NET, and JSP are used to generate dynamic web pages and are interpreted by applications on the server. It provides examples of programming concepts supported by server-side languages like variables, arrays, functions, loops and conditional statements. It also discusses using server-side scripts to communicate with databases and store/retrieve information.

1. Server-Side Scripting
Session 18

2. • In order to generate dynamic pages we use a server-
side scripting language.
• There are different types of server-side scripting
languages such as PHP, ASP,ASP.NET, ColdFusion, JSP,
Perl and others.
• Each scripting languages is being interpreted by an
application.
• The application which interprets the server-side
script is installed on the sever just like any other
application.
• PHP uses apache which comes with XAMPP & WAMP

3. • Server-side scripting languages are also operating
systems dependent.
• Each server-side scripting languages supports
basic programming concepts such as variables,
arrays, functions, loops, conditional statement and
others.
• They also contain more specific elements such as
special objects, commands used to communicate
with the server and a database and much more.

4. • When there is a need to store and retrieve
information (user names, items in stock etc.) a
database will be used to contain the data.
• Sever-side script can communicate to a database
using a structured query language (SQL) which
manipulates the database (add, remove, update
etc.)
• More on that next week.

5. Three Tier Web
Applications

6. PHP - Hypertext Preprocessor
In 1994 he created
the PHP scripting language,
authoring the first two
versions of the language
Some really large PHP websites
• Facebook
• Wikipedia
• Flickr
• Yahoo! Answers
• Yahoo! Bookmarks
• SourceForge
• Photobucket
• YouTube
Rasmus Lerdorf
(born 22 November 1968)

7. • You cannot view the PHP source code by selecting
"View source" in the browser – you will only see
the output from the PHP file, which is plain HTML.
• This is because the scripts are executed on the
server before the result is sent back to the
browser.
• A PHP scripting block always starts with <?php and
ends with ?>.
• A PHP scripting block can be placed anywhere in
the document.

8. • On servers with shorthand support enabled you
can start a scripting block with <?
• and end with ?>.
• However, for maximum compatibility, we
recommend that you use the standard form
(<?php) rather than the shorthand form.
• A PHP file normally contains HTML tags, just like
an HTML file, and some PHP scripting code.

9. • 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.
• There are two basic statements to output text
with PHP: echo and print. In the
• example above we have used the echo statement
to output the text "Hello World".

10. • Variables are used for storing a values, like text
strings, numbers or arrays.
• When a variable is set it can be used over and
over again in your script
• All variables in PHP start with a $ sign symbol.
• The correct way of setting a variable in PHP:
$var_name = value;

11. • In PHP a variable does not need to be declared
before being set.
• In the previous example, you see that you do not
have to tell PHP which data type the variable is.
• PHP automatically converts the variable to the
correct data type, depending on how they are
set.
• In a strongly typed programming language, you
have to declare (define) the type and name of
the variable before using it.
• In PHP the variable is declared automatically
when you use it.

12. • A variable name must start with a letter or an
underscore "_"
• A variable name can only contain alpha-numeric
characters and underscores (a-Z, 0-9, and _ )
• A variable name should not contain spaces.
• If a variable name is more than one word, it
should be separated with underscore
($my_string), or with capitalization ($myString)

13. • Very often when you write code, you want to
perform different actions for different decisions.
• You can use conditional statements in your code
to do this.
If (condition)
…code1
Else
…code 2

14. • If you want to select one of many blocks of code
to be executed, use the Switch statement.
• The switch statement is used to avoid long blocks
of if..elseif..else code.

15. switch (expression)
{
case label1:
code to be executed if expression = label1;
break;
case label2:
code to be executed if expression = label2;
break;
default:
code to be executed if expression is different from both
label1 and label2;
}

16. for(initialization; test_condition;loop_update)
{
statement(s)
}
• The test_condition uses relational and logical
operators (<,>,>=,<, &&, ||, etc).
• It is checked at the end of each iteration of the
loop.
• If the condition is still true then another iteration
of the loop is undertaken

17. The While Loop -Syntax
while (condition=TRUE)
{
statement(s)
}
• The lines of code within {} brackets are repeated as
long as the condition specified in the while statement
is TRUE.
• The condition is checked BEFORE each iteration of
the loop.
• The actual condition can be a single condition or a
logical combination of individual conditions (using
logical operators - &&, || or !).

18. The Do While Loop - Syntax
do
{
//statement(s);
} while (condition=TRUE);
• Statement(s) is/are executed, and condition is
evaluated if the value of condition is TRUE, then control
passes back to the beginning of the do statement, and
the process repeats itself.
• When condition is FALSE, then control passes to next
statement bellow the loop block.