Server Scripting Language -PHP

Server-Side Scripting
CIVE-IPT 2014 Day 8
Presented by Deo Shao

• 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

• 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.

• 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.

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)

Basic PHP Syntax
• 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.

Basic PHP Syntax
• 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.

Basic PHP Syntax
• 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".

PHP Variables
• 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;

PHP Variables
• 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.

PHP Variables
• 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)

Conditional Statements
• 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

The Switch Statement - Syntax
• 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.

The Switch Statement - Syntax
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;
}

The For loop- Syntax
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

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 !).

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.

Server Scripting Language -PHP

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