Our "Show PHP" tool makes it easy to learn PHP, it shows both the
PHP source
code and the HTML output of the code.
PHP 5 References
You will find complete references of all PHP functions:
- Array functions
- Calendar functions
- Date functions
- Directory functions
- Error functions
- Filesystem functions
- Filter functions
- FTP functions
- HTTP functions
- LibXML functions
- Mail functions
- Math functions
- Misc functions
- MySQLi functions
- SimpleXML functions
- String functions
- XML Parser functions
- Zip functions
What You Should Already Know
Before you continue you should have a basic understanding of the following:
What is PHP?
- PHP is an acronym for "PHP: Hypertext Preprocessor"
- PHP is a widely-used, open source scripting language
- PHP scripts are executed on the server
- PHP is free to download and use
PHP is an amazing and popular language!
It is powerful enough to be at the core of the biggest
blogging system on the web (WordPress)!
It is deep enough to run the largest social network
(Facebook)!
It is also easy enough to be a beginner's first server side
language!
What is a PHP File?
- PHP files can contain text, HTML, CSS, JavaScript, and PHP code
- PHP code are executed on the server, and the result is returned to the browser as plain HTML
- PHP files have extension ".php"
What Can PHP Do?
- PHP can generate dynamic page content
- PHP can create, open, read, write, delete, and close files on the server
- PHP can collect form data
- PHP can send and receive cookies
- PHP can add, delete, modify data in your database
- PHP can be used to control user-access
- PHP can encrypt data
With PHP you are not limited to output HTML. You can output images, PDF
files, and even Flash movies. You can also output any text, such as XHTML and
XML.
Why PHP?
- PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
- PHP is compatible with almost all servers used today (Apache, IIS, etc.)
- PHP supports a wide range of databases
- PHP is free. Download it from the official PHP resource: www.php.net
- PHP is easy to learn and runs efficiently on the server side
PHP 5 Installation
What Do I Need?
To start using PHP, you can:
- Find a web host with PHP and MySQL support
- Install a web server on your own PC, and then install PHP and MySQL
Use a Web Host With PHP Support
If your server has activated support for PHP you do not
need to do anything.
Just create some .php files, place them in your web directory, and the server
will automatically parse them for you.
You do not need to compile anything or install any extra tools.
Because PHP is free, most web hosts
offer PHP support.
Set Up PHP on Your Own PC
However, if your server does not support PHP, you must:
- install a web server
- install PHP
- install a database, such as MySQL
The official PHP website (PHP.net) has installation instructions for PHP:
http://php.net/manual/en/install.php
PHP 5 Syntax
A PHP script is executed on the server, and the plain HTML result is sent back to the browser.
Basic PHP Syntax
A PHP script can be placed anywhere in the document.
A PHP script starts with
<?php and ends with
?>:
<?php
// PHP code goes here
?>
The default file extension for PHP files is ".php".
A PHP file normally contains HTML tags, and some PHP scripting code.
Below, we have an example of a simple PHP file, with a PHP script that uses a
built-in PHP function "echo" to output the text
"Hello World!" on a web page:
Example
<!DOCTYPE html>
<html>
<body>
<h1>My first PHP page</h1>
<?php
echo "Hello World!";
?>
</body>
</html>
Note: PHP statements end with a semicolon (;).
Comments in PHP
A comment in PHP code is a line that is not read/executed as part of the
program. Its only purpose is to be read by someone who is looking at the code.
Comments can be used to:
- Let others understand what you are doing
- Remind yourself of what you did - Most programmers have
experienced coming back to their own work a year or two later and having
to re-figure out what they did. Comments can remind you of what you
were thinking when you wrote the code
PHP supports several ways of commenting:
Example
<!DOCTYPE html>
<html>
<body>
<?php
// This is a single-line comment
# This is also a single-line comment
/*
This is a multiple-lines comment block
that spans over multiple
lines
*/
// You can also use comments to leave out parts of a code line$x = 5 /* + 15 */ + 5;
echo $x;
?>
</body>
</html>
PHP Case Sensitivity
In PHP, all keywords (e.g. if, else, while, echo, etc.), classes, functions,
and user-defined functions are NOT case-sensitive.
In the example below, all three echo statements below are legal (and equal):
Example
<!DOCTYPE html>
<html>
<body>
<?php
ECHO "Hello World!<br>";
echo "Hello World!<br>";
EcHo "Hello World!<br>";
?>
</body>
</html>
However; all variable names are case-sensitive.
In the example below, only the first statement will display the value of the
$color variable (this is because $color, $COLOR, and $coLOR are treated as three
different variables):
Example
<!DOCTYPE html>
<html>
<body>
<?php
$color = "red";
echo "My car is " . $color . "<br>";
echo "My house is " . $COLOR . "<br>";
echo "My boat is " . $coLOR . "<br>";
?>
</body>
</html>
Comments