html - How to store a root domain as a variable in php and use it to move between folders

I am in the process of creating a website using php and due to hosting my website locally and then uploading it onto a server I want an easy way of changing the root domain without manually changing it in every single place I have a domain, so I proposed storing the root domain as a variable. n.b. I have simplified down the names of the files.

I created a a variable called $rootDomain

<?php
$rootDomain = "http://localhost/testWebsite/";
?>

Next I have a new page in a sub folder called: page.php. I get to this page via a link in a header that is used for all the pages.

<a href=<?php  $rootDomain?>"pageone/page.php"><li><?php echo$firstLink?></li>

Using the generic header I have on all pages I want to get back to the main index page. The link used looks like this:

<a href=<?php  $rootDomain?>"index.php"><?php echo$websiteName?></a>

The expected link location should send me to:

"http://localhost/testWebsite/index.php"

But the link it is displaying is:

"http://localhost/testWebsite/pageone/index.php"

Which is an error.

When I have tested it using the link directly without the variable :

<a href="http://localhost/index.php"><?php echo$websiteName?></a>

There is no error and I get the expected outcome.

I am struggling to work out what I am doing wrong and any help would be much appreciated.

Solution:

You have to echo the variable in the href attribute with PHP for it to show in the HTML output.

You can do so by doing

    <a href="<?php echo $rootDomain; ?>index.php"><?php echo $websiteName; ?></a>

or you can use the short echo syntax

    <a href="<?= $rootDomain ?>index.php"><?= $websiteName ?></a>

You also have a couple typos in your code, like the misplaced quotes around the href attribute.