Variables in PHP
Variables are used for storing values, such as numbers, strings or function results, so that they can be used many times in a script.
Variables in PHP
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; |
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 with a string, and a variable with a number:
<?php $txt = "Hello World!"; $number = 16; ?> |
PHP is a Loosely Typed Language
In PHP a variable does not need to be declared before being set.
In the example above, you see that you do not have to tell PHP which data type the variable is.
PHP automatically converts the variable to the correct data type, depending on how they are set.
In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.
In PHP the variable is declared automatically when you use it.
Variable Naming Rules
- A variable name must start with a letter or an underscore “_”
- A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )
- A variable name should not contain spaces. If a variable name is more than one word, it should be separated with underscore ($my_string), or with capitalization ($myString)
Basic PHP Syntax
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:
<html> <body> <?php echo "Hello World"; ?> </body> </html> |
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 the .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.
<html> <body> <?php //This is a comment /* This is a comment block */ ?> </body> </html> |
How to install PHP?
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
You can find instructions on the links above on how to use the apache server, mysql server etc. For any questions, please feel free to drop in comments and I shall get back to you.
What is PHP?
Introduction to PHPPHP is a server-side scripting language. What You Should Already KnowBefore you continue you should have a basic understanding of the following:
What is PHP?
What is a PHP File?
What is MySQL?
PHP + MySQL
Why PHP?
Where to Start?To get access to a web server with PHP support, you can:
|