Passing variables with data between pages using URL

There are different ways by which values of variables can be passed between pages. One of the ways is to use the URL to pass the values or data. Here the biggest advantage is we can pass data to a different site even running at different servers. Any scripting language like ASP, JSP, PHP or Perl running at receiving end can process and collect the value from the query string or from the URL. Here one main concern is the data gets exposed in address bar of the browser and can be easily accessible by using browser history. So this is not a good idea to pass sensitive data like password through the URL to different pages or different sites.

Here is an example of passing data through URL within a site.

<a href='page2.php?id=2489&user=tom'>link to page2</a>

When the above link is clicked, page2.php gets the variables id and user with data 2489 and tom respectively. The address of page2.php can be replaced with any site name and the same data can be passed to another site running in any server. Like this

Passing data outside

<a href=http://www.sitename.com/index.php?id=2489&user=tom>Link to another site</a>

Related Tutorial
• passing Array through URL • urlencode

Demo of passing data through a form

You can see in the above case the values can be posted to another site. Note that after the page name we are using question mark ( ? ) to start the variable data pair and we are separating each variable data pair with one ampersand ( & ) mark.

Submitting form values through GET method

A web form when the method is set to GET method, it submits the values through URL. So we can use one form to generate an URL with variables and data by taking inputs from the users. The form will send the data to a page within the site or outside the site by formatting a query string.

<form method=GET action='http://www.anysite.com/index.php'>

Submitting a form through POST method

By post method of form submission we can send more number or length of data. Sensitive information like password does not get exposed in URL by POST method, so our login forms we should use POST method to submit data. This is how we collect data submitted by POST method in PHP

$id=$_POST['id'];
$password=$_POST['password'];

Collecting data submitted by either GET or POST method

If a page is receiving a data which can come in any one of the method GET or POST then how to collect it ? Here we are not sure how to collect the data. So we will use like this.

$id=$_REQUEST['id'];
$password=$_REQUEST['password'];

Every scripting language pages has its own way of receiving the data from the URL

While receiving the data based on the server settings the values will be available to the pages. Here in a server running PHP will have to see the global settings of the server on how to collect the data.

$id=$_GET['id'];
$user=$_GET['user'];

Same way in ASP environment running VB script the data can be collected and assigned like this

Id = Request.QueryString("id")
User = Request.QueryString(“user”)

Passing data within the site using URL

The same principle is used like above to send the data within the site using URL. A query sting can be formatted with a link or a form can be used with get method to pass variables between pages.

Passing the data between the site through URL

Like above data can be passed to different pages of sites using URL . The best use is directly linking to a page dip inside another site by formatting a query sting. Like this <a href=http://www.sitename.com/viewtopic.php?id=5248>Linking to a topic</a>

Passing variables through query string

In many applications we need to pass variables through query string. For example we want to display the product details where product ID is to be passed in query string through a variable. The product ID can be collected from a table so we don't know what is the value but we can use the variable which stores the product ID.

For example let us say we have collected product id from the product table. Read the tutorial on how to collect data from table. Our link with query string will have something like this.

$pid=$nt[product_id];
echo "<a href=product-detail.php?product_id=$pid>Product Details</a>";

You can directly display like this also.

echo "<a href='product-detail.php?product_id=$nt[product_id]'>Product Details</a>";

Chang of data while passing through URL

There is a problem in sending data other than plain text through browser. Empty space and some characters like & if present in the data , will create problem. To maintain the data integrity we have to encode the data before sending them though URL and then decode them again to get back the original data. In PHP encode command is used and in ASP VBScript the command is Server.URLEncode(string)

Security issues while posting data through URL

The most common type of security problem in using data from URL is injection attack. We must sanitize the date before using inside our script or generating any query to manage database.

Variables and Constants in PHP

PHP Variables how to declare or how to use them in Script
Passing variables with data between pages 
Taking Variables through URL to different pages within & outside the site
By Cookies
isset: to check variable exist or not
var_dump: Getting details about a variable
unset: Unset a variable
empty: Checking if variable is empty or not
constant: getting the value stored in a constant
define: declaring a constant and its value
defined: checking constant exist or not
urlencode: Encoding variablas before sending then through URL
Session Variables:Starting storing and destroying Sessions with Session ID

ash	28-07-2009
How to pass a file via URL. Eg a file is uploaded in using doGet() and in doPost it is collected using request.getInputStream()
kashif murtaza	23-10-2009
thanks for help... it's good for understanding concept of href..
campsmore	08-02-2010
Can you use the data variable that was passed in the URL in an "include" statement to display information inside the current page that is related to the data in the variable?
ruby	14-02-2010
how to data transfer between two members in login concept
BigDave	27-05-2010
In the first example, what if, instead of sending Tom, I need to send the value of a variable?
ramchan	23-07-2010
I need a help in PHP of passing a content of search result from one web site to another web site. I am not having any idea about this can u help me sir.
Sashi	18-08-2010
How can i rethieve the mode/id values into an xsl page of the following url line... http. localhost/updatingXML/tool_Edit.asp?mode=view&id=2
smo	22-08-2010
In ASP the get method of collecting data
jessica	23-08-2010
how can i pass values with a drop down menu which contains a list of manufacturers name.i want the code to display a value of a variable each time a manufacturer name is selected through the drop down
JohnR	12-10-2010
What PHP code do I use to Post form data to a MYSQL database and at the same time send only some form values to another web page hosted on a different URL.? Thanks!
siva	13-12-2010
i can understood the $_POST, but how $_GET works ,
adi	11-09-2011
which menthod gets executed when we click on hyperlink?
Power Wong	25-01-2012
adi, should be $_GET method. For example, the url is: xxxxxx/my_prog.php?my_id=1234 Then inside my_prog.php, you can use $_GET[my_id] to get the 1234 like the below $my_var = $_GET[my_id]
David	22-03-2012
I have 2 separate php environments which I like to have a pass-through of registration and login built. Any help will greatly be appreciated.
debabrata puthal	07-04-2012
create a form with 2 fields that is username and password then make the server side validation chec if the fields and blank or not,then compare your username and password with server username,password,if equal display on page valid user or display invalid user.
tripti	06-06-2012
i need to get how to send an ip address value to ip2location text box to evaluate the location n return it

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