PHP is a server-side scripting language.

What You Should Already Know

Before you continue you should have a basic understanding of the following:

HTML/XHTML
JavaScript

What is PHP?

PHP stands for PHP: Hypertext Preprocessor
PHP is a server-side scripting language, like ASP
PHP scripts are executed on the server
PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid,
PostgreSQL, Generic ODBC, etc.)
PHP is an open source software
PHP is free to download and use

What is a PHP File?

PHP files can contain text, HTML tags and scripts
PHP files are returned to the browser as plain HTML
PHP files have a file extension of ".php", ".php3", or ".phtml"

What is MySQL?

MySQL is a database server
MySQL is ideal for both small and large applications
MySQL supports standard SQL
MySQL compiles on a number of platforms
MySQL is free to download and use

PHP + MySQL

PHP combined with MySQL are cross-platform (you can develop in
Windows and serve on a Unix platform)

Why PHP?

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

Where to Start?

To get access to a web server with PHP support, you can:

Install Apache (or IIS) on your own server, install PHP, and MySQL
Or find a web hosting plan with PHP and MySQL support

PHP Installation

What do you Need?

If your server supports PHP you don't
need to do anything.

Just create some .php files in your web directory, and the server
will parse them for you. Because it is free, most web hosts
offer PHP support.

However, if your server does not support PHP, you must install PHP.

Here is a link to a good tutorial from PHP.net on how to install PHP5:

http://www.php.net/manual/en/install.php

Download PHP

Download PHP for free here:
http://www.php.net/downloads.php

Download MySQL Database

Download MySQL for free here:
http://www.mysql.com/downloads/index.html

Download Apache Server

Download Apache for free here:

http://httpd.apache.org/download.cgi

PHP code is executed on the server, and the plain HTML result
is sent to the browser.

Basic PHP Syntax

A PHP scripting block always starts with <?php and ends with ?>.
A PHP scripting block can be placed anywhere in the document.

On servers with shorthand support enabled you can start a scripting
block with <? and end with ?>.

For maximum compatibility, we recommend that you use the standard
form (<?php) rather than the shorthand form.

<?php

?>

A PHP file normally contains HTML tags, just like an HTML file, and some PHP
scripting code.

Below, we have an example of a simple PHP script which sends the text
"Hello World" to the browser:

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".

Note: The file must have a .php extension. If the file has a .html
extension, the PHP code will not be executed.

Comments in PHP

In PHP, we use // to make a single-line comment or /* and */ to make a
large comment block.

PHP Variables

A variable is used to store information.

Variables in PHP

Variables are used for storing a values, like text strings, numbers or
arrays.

When a variable is declared, it can be used over and over again in your script.

All variables in PHP start with a $ sign symbol.

The correct way of declaring a variable in PHP:

$var_name = value;

New PHP programmers often forget the $ sign at the beginning of the
variable. In that case it will not work.

Let's try creating a variable containing a string, and a variable containing a number:

<?php

$txt="Hello World!";

$x=16;

?>

PHP is a Loosely Typed Language

In PHP, a variable does not need to be declared before adding a value to it.

In the example above, 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 its value.

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.

Naming Rules for 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, 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
an underscore ($my_string), or with capitalization ($myString)

Knowledge Pool

NITC

Friday, February 5, 2010

PHP Basics