What is
Super global variable
Example a super global variable include
$_GET
$_POST
3. $_SESSION
4. $_REQUEST
$_COOKIE
$_SERVER
7. $_FILES
1. $_GET
Example :-
For example ,if a user
visits a website with a url that looks
like this :” showphp.php?filename=demo_global_get”;
2. $_POST
In PHP, The $_POST variable is a super global variable that
is used collect data passed in an HTTP request using the POST method .The POST
method is typically used to submit data to the server ,such as when a user
fills out a form on a website .
For example ,if a
user fille out a form with fields for their name and number and submit it ,the _POST variable
would contain an array with keys “name”
and “number” and the value entered by
the user.
<form
action =”<?php echo $_SERVER[‘PHP_SELF’];
?>” method=”post”>
<input
type=”text” name =”name”>
<input
type=”submit” >
</form>
<?php
If($_SERVER[“REQUEST_METHOD”]==$_POST)
{
$name=$_POST[‘name’];
If(empty($name))
{
Echo “Name
is empty”;
}else{
Echo $name;
}
}
?>
3. $_SESSION
In PHP ,The $_SESSION variable is a super global variable that is
used to store data on the server that is
specific to a user session .A session is
a way to store information (in variable)
To be used across multiple page. When a user visits a
website a new session is created and a unique
session ID is generated.
The $_SESSION variable is an associative array that stores
data specific to a user`s session.
The data can be stored in the session using the following syntax:
$_SESSION[‘key’]=
value;
And then accessed using following syntax:-
$value=$_SESSION[‘key’];
When the user closed browser or otherwise ends the session
,the session data is destroyed.
Note:- It is important to use session_start() function at the
beginning of every page that you want to access session data.
4. $_COOKIE
In PHP, the $_COOKIE variable is a super global variable that
is used to store and retrieve data in the form of cookie. A cookie is a small
piece of data that is stored on the user`s computer by
the web browser. Cookie are typically used to remember information about a user ,such as their perferences or login details.
The $_Cookie variable is an associative array that stores
data in the form of key-value pairs where the key is the name of the cookie and
the value is the data stored in the cookie.
For example you can used the setcookie() function to create a
new and store data in ,it and then access the data later using the $_COOKIE variable.
For example ,to set a cookie
named “username” with the value “Ram”;
Setcookie(‘username’,
’Ram’, time()+(86400*30),”/”);
And then you can access the data like this
$username=$_COOKIE[‘username’];
Cookie are stored on the
user`s computer and are sent
back to the server with every request , so they can be used to persist
data across multiple page requests. It
is important to keep in mind that cookies can be deleted by the user or expire after a certain period of time.
5. $_SERVER
In PHP , the $_SERVER
variable is a super global variable that provides information about the
server and the current script environment .it is an associative array that
contains information such as the servers
software, the current script file path , and information about the request such
and IP address.
Same of the most commonly used element in the $_SERVER array
include:-
·
$_SERVER[‘REQUEST_URL’] Which
contains the URL of the current request.
·
$_SERVER[‘HTTP_HOST’] which
contains the hostname of the server that the script is running on.
·
$_SERVER[‘REQUEST_METHOD’] which contain the request method (GET ,POST,
etc)
·
$_SERVER[‘REMOTE_ADDR’] which contain IP address of the user making
the request .
·
$_SERVER[‘SERVER_NAME’] Which
contain the hostname
·
$_SERVER[‘SERVER_SOFTWARE’] Which
contain s the server software version .
These variable can be useful in version scenarios such as
logging create dynamic link, redirecting
and security purposes.
6. $_REQUEST
In PHP , the $_REQUEST variable is a super global variable
that is used collect data from various sources , including the $_GET ,$_POST and $_COOKIE variable .the
$_REQUEST variable is an associative array that store data passed in an HTTP request.
For example , if a
form uses the GET method to submit data will be stored in the $_GET variable
,but it can also be accessed using
the $_REQUEST variable.
<form
action=”name.php” method=”get”>
<input
type=”text” name =”name”>
<input
type=”submit” >
</form>
IN this example , the
value entered in the form can be accessed using either $_GET[‘name’] or
$_REQUEST[‘name’].
7. $_FILES
In PHP ,the $_FILES variable is a super global variable that is
used to handle file uploads . the $_FILES variable is an associative array that
information about the uploaded files, such as their names , types , and size.
When a files is
uploaded via a form ,the data is sent to the server in the form
of a multipart HTTP request . The $_FILES
variable is used to access the files data
on the server side. The $_FILES array contains several element for each files uploaded
,such as:
$_FILES[‘file_field_name’][‘name’] which
contain the original name of the file o the client`s computer
$_FILES[‘file_field_name’][‘type’] which
contains the MIME type of the file
$_FILES[‘file_field_name’][‘size’] which
contains the size of the file in bytes.
$_FILES[‘file_field_name’][‘tmp_name’] which
contains the temporary name of the file store on the server
$_FILES[‘file_field_name’][‘error’]
which contain the error code associated with the file upload.
For
example
$file_name=$_FILES[‘userfile’][‘name’];
$file_size=$_FILES[‘userfile’][‘size’];
$file_type=$_FILES[‘userfile’][‘type’];
$file_tmp_name=$_FILES[‘userfile’][‘tmp_name’];
$file_error =$_FILES[‘userfile’][‘error’];
It`s important to note that file uploads are subject to various security considerations such as file size ,file type, and file name validation ,and it`s important to validate the file before storing it on the server.
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