How do I add a parameter to a URL like '?=website-name' - url

Question

Like the question says, how do I add a parameter to a URL?
Example:
When you click on a link to get a featured product on Product Hunt, the URL is appended with ?ref=producthunt.
Can I just add a parameter like this manually to the few links that I have on my website? Are there any scenarios where this might be suboptimal to do?

Answer 1

The parameters in the URL correspond to the superglobal $_GET array.
It means that if your URL is in the form
www.domain.com?key1=val1&key2=val2 ,
then $_GET[key1] contains val1 , and so on.
It is perfectly legitimate to add these parameters manually in a link (a typical use case would be a login button, which redirects you to the current URL and appends &todo=login . You can then add a bit of PHP code that triggers the login process when $_GET contains the value 'login' at the key 'todo').
The other way of adding these parameters is forms. In an HTML form, you specify a 'method' which can be 'get' or 'post'.
If you choose 'get', when the form is submitted, the URL will automatically be appended with the form answers.
NB: It is generally NOT SAFE to directly read values from the $_GET, as the user can fill it with any value (just by changing the URL) so it is good practice to use filters that ensure inputs are safe. Check http://www.w3schools.com/php/php_filter.asp for more on filters

Answer 2

The parameters added to the url is called query string and they have a format
it must start will ?
every paraper will be seperated with &
Example: http://www.yoururl.com?name=myname&age=34&ect=somethingelse
The mistake you did is by putting ?= which is not converted by your web server.
you can pas like '?websitename=website-name'

Answer 3

Querystring parameters are key value pairs that are separated from the URL's domain and path with a ? and separated from each other with an &, i.e ?key=value&key2=value2.
The values can be accessed client-side (in Javascript) and server-side by the webserver or by a server-side language is being used, PHP, ASP.NET, Java.
Some values should be encoded using a function such as encodeURIComponent to ensure that they are valid.
Risks
You need to be careful that the querystring does not contain any sensitive information such as a sequential order number, i.e ?order=5 as someone could manually change the value to see another user's order (?order=6, if no other authentication in place). The order value should be encrypted so it cannot be guessed. Also, do not execute any code passed in on the querystring with eval() as the contents could be changed by a malicious user to execute a crosssite scripting (XSS) attack on another user and steal their cookie or login credentials.