Issues with using PHP Swift Mailer

Question

What I have done:

1. ) Downloaded Swift-4.1.5.tar
2. ) Extracted it
3. ) Uploaded to my host in /public_html/domain/lib using FileZilla
4. ) Made a new script using the code below.
5. ) Opened it in the Browser and I got the following error below

So my question is, how am I getting the error that the file doesn't exist if It's 100% there? Thanks!

    <?php

      require_once '/public_html/domain/lib/swift_required.php';

    ?>

Warning: require_once(/public_html/domain/lib/swift_required.php) [function.require-once]: failed to open stream: No such file or directory in /home/myuser/public_html/domain/email.php on line 5

Fatal error: require_once() [function.require]: Failed opening required '/public_html/domain/lib/swift_required.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/myuser/public_html/domain/email.php on line 5

Here's a screenshot of my dir from FileZilla. http://i.imgur.com/Zsy8y.jpg

Answer 1

This is wrong:

// this is absolute path, just like /home/user or /var/www
require_once '/public_html/domain/lib/swift_required.php'; 

Use instead:

// this is relative path to the current file
require_once 'public_html/domain/lib/swift_required.php'; //notice: no '/' in the beggining

OR:

// so use this one if you know the whole path to the file
require_once ABSOLUTE_PATH_TO . 'public_html/domain/lib/swift_required.php';

OR:

// or use this one if you don't know the whole path
// or if the path will change (dev machine and production machine)
require_once dirname(__FILE__) . RELATIVE_PATH_TO . 'public_html/domain/lib/swift_required.php';