PHP Introduction
PHP is a recursive acronym for “PHP:
Hypertext Preprocessor” -- It is a widely-used
open source general-purpose scripting
language that is especially suited for web
development and can be embedded into
HTML.
PHP Introduction
PHP is a server-side scripting language
PHP scripts are executed on the server
PHP supports many databases (MySQL,
Informix, Oracle, Sybase, Solid, PostgreSQL,
Generic ODBC, etc.)
PHP is open source software
PHP is free to download and use
PHP Introduction
PHP runs on different platforms (Windows,
Linux, Unix, etc.)
PHP is compatible with almost all servers
used today (Apache, IIS, etc.)
PHP is FREE to download from the official
PHP resource: www.php.net
PHP is easy to learn and runs efficiently on
the server side
PHP Introduction
Instead of lots of commands to output HTML
(as seen in C or Perl), PHP pages contain HTML
with embedded code that does "something"
(like in the next slide, it outputs "Hi, I'm a PHP
script!").
The PHP code is enclosed in special start and
end processing instructions <?php and ?> that
allow you to jump into and out of "PHP mode."
PHP Introduction
PHP Introduction
PHP code is executed on the server,
generating HTML which is then sent to the
client. The client would receive the results of
running that script, but would not know what
the underlying code was.
A visual, if you please...
PHP Introduction
PHP Getting Started
On windows, you can download and install
WAMP. With one installation and you get an
Apache webserver, database server and php.
http://www.wampserver.com
On mac, you can download and install MAMP.
http://www.mamp.info/en/index.html
PHP Hello World
Above is the PHP source code.
PHP Hello World
It renders as HTML that looks like this:
PHP Hello World
This program is extremely simple and you
really did not need to use PHP to create a page
like this. All it does is display: Hello World using
the PHP echo() statement.
Think of this as a normal HTML file which
happens to have a set of special tags available
to you that do a lot of interesting things.
PHP Comments
In PHP, we use // to
make a single-line
comment or /* and */ to
make a large comment
block.
PHP: The Basics
What is it?
PHP is a scripting language commonly used
on web servers.
Stands for “PHP: Hypertext Preprocessor”
Open source
Embedded code
Comparable with ASP
Multiple operating systems/web servers
The PHP Resource
www.php.net
What can it do?
Dynamic generation of web-page content
Database interaction
Processing of user supplied data
Email
File handling
Text processing
Network interaction
And more…
Fundamentals
PHP is embedded within xhtml pages within
the tags: <?php … ?>
The short version of these tags can also be
used: <? … ?>
Each line of PHP is terminated, like MySQL,
with a semi-colon.
Hello World!
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<?php echo ‘<p>Hello World!</p>’; ?>
</body>
</html>
Preparing to code with PHP
Literals..
All strings must be enclosed in single of
double quotes: ‘Hello’ or “Hello”.
Numbers are not in enclosed in quotes: 1 or
45 or 34.564
Booleans (true/flase) can be written directly
as true or false.
Comments
// This is a comment
# This is also a comment
/* This is a comment
that is spread over
multiple lines */
Do not nest multi-line comments
// recommended over #
Comments
<?php
// this is a comment
echo ‘Hello World!’;
/* another
multi-line comment */
?>
Displaying Data
There are two language constructs available
to display data: print() and echo().
They can be used with or without brackets.
Note that the data ‘displayed’ by PHP is
actually parsed by your browser as HTML.
View source to see actual output.
Displaying data
<?php
echo ‘Hello World!<br />’;
echo(‘Hello World!<br />’);
print ‘Hello World!<br />’;
print(‘Hello World!<br />’);
?>
Escaping Characters
Some characters are considered ‘special’
Escape these with a backslash \
Special characters will be flagged when they
arise, for example a double or single quote
belong in this group…
Escaping Characters
<?php
// Claire O’Reilly said “Hello”.
echo ‘Claire O\’Reilly ’;
echo “said \”Hello\”.”;
?>
Variables: What are they?
When we work in PHP, we often need a
labelled place to store a value (be it a string,
number, whatever) so we can use it in
multiple places in our script.
These labelled ‘places’ are called
VARIABLES
Variables: Naming
$ followed by variable name
Case sensitive
$variable differs from $Variable
Stick to lower-case to be sure!
Name must started with a letter or an
underscore
Followed by any number of letters, numbers
and underscores
Variables: example
<?php
$name = ‘Phil’;
$age = 23;
echo $name;
echo ’ is ‘;
echo $age;
// Phil is 23
?>
Constants
Constants (unchangeable
variables) can also be defined.
Each constant is given a name
(note no preceding dollar is
applied here).
By convention, constant names
are usually in UPPERCASE.
Constants
<?php
define(‘NAME’,‘Phil’);
define(‘AGE’,23);
echo NAME;
echo ’ is ‘;
echo AGE;
// Phil is 23
?>
“ or ‘ ?
There is a difference between strings written
in single and double quotes.
In a double-quoted string any variable names
are expanded to their values.
In a single-quoted string, no variable
expansion takes place.
“ or ‘ ?
<?php
$name = ‘Phil’;
$age = 23;
echo “$name is $age”;
// Phil is 23
?>
“ or ‘ ?
<?php
$name = ‘Phil’;
$age = 23;
echo ‘$name is $age’;
// $name is $age
?>
Review
We’ve started PHP..
Escaping XHTML
Comments
Basic Syntax
Variables
Constants
THANK YOU
