Variables are containers that store information in PHP. A variable starts with $ followed by its name. Variables can be either local or global in scope. The global keyword is used to access global variables from within functions, and the static keyword prevents a local variable from being deleted after function execution ends. PHP also has superglobal variables that are accessible anywhere and provide environment information like $_SERVER, $_GET, and $_POST which are used to collect form data.

1. VARIABLES
BY
SANA MATEEN

2. PHP VARIABLES
• Variables are "containers" for storing information.
• CREATING (DECLARING) PHP VARIABLES
• In PHP, a variable starts with the $ sign, followed by the name of the
variable:
• Example
• <?php
$txt = "Hello world!";
$x = 5;
$y = 10.5;
?>
• Note: When you assign a text value to a variable, put quotes around the
value.
• Unlike other programming languages, PHP has no command for declaring a
variable. It is created the moment you first assign a value to it.
• A variable can have a short name (like x and y) or a more descriptive
name (age, carname, total_volume).
• Rules for PHP variables:
• A variable starts with the $ sign, followed by the name of the variable
• A variable name must start with a letter or the underscore character
• A variable name cannot start with a number
• A variable name can only contain alpha-numeric characters and underscores
(A-z, 0-9, and _ )
• Variable names are case-sensitive ($age and $AGE are two different
variables)

3. PHP VARIABLES SCOPE
• In PHP, variables can be declared anywhere in the
script.
• The scope of a variable is the part of the script
where the variable can be referenced/used.
• PHP has three different variable scopes:
• local
• global
• static
• Global and Local Scope
• A variable declared outside a function has a
GLOBAL SCOPE and can only be accessed outside
a function:
• A variable declared within a function has a LOCAL
SCOPE and can only be accessed within that
function:
global
local

4. PHP THE GLOBAL KEYWORD
• The global keyword is used
to access a global variable
from within a function.
• To do this, use the global
keyword before the variables
(inside the function):
• PHP also stores all global
variables in an array called
$GLOBALS[index].
The index holds the name of
the variable. This array is
also accessible from within
functions and can be used to
update global variables
directly.

5. PHP THE STATIC KEYWORD
• Normally, when a function
is completed/executed, all
of its variables are deleted.
• However, sometimes we
want a local variable NOT
to be deleted. We need it for
a further job.
• To do this, use
the static keyword when
you first declare the
variable:

6. PHP’S SUPERGLOBAL VARIABLES
• PHP offers a number of useful predefined variables
that are accessible from anywhere within the
executing script and provide you with a substantial
amount of environment-specific information.
• You can shift through these variables to retrieve
details about
1. the current user session,
2. the user’s operating environment,
3. the local operating environment, and more.
• PHP creates some of the variables, while the
availability and value of many of the other variables
are specific to the operating system and web server.

7. As you can see, quite a bit of information is available—some useful, some not so useful.
You can display just one of these variables simply by treating it as a regular variable. For
example, use this to display the user’s IP address:
printf("Your IP address is: %s", $_SERVER['REMOTE_ADDR']);
This returns a numerical IP address, such as 192.0.34.166.

8. $_POST and $_GET
• The PHP superglobals $_GET and $_POST are used to collect form-data.

9. 6.Vii lab program

11. 6.ii.Lab program

12. $_REQUEST is a super global variable which
is widely used to collect data after submitting
html forms.
The simplexml_load_file() function converts
the specified XML file into a
SimpleXMLElement object.