Create comma separated list of links with variable in PHP - php

Question

I have a variable which renders a list of usernames. Now, I need to add a link to each username. The link is built from a fixed URL and the username as a variable.
Example link:
https://www.example.org/something?userid=$username
$usernames = $_POST['username'];
$username = '';
foreach($usernames as $value) {
$username .= "'" . $value . "', ";
}
$username = rtrim($username, ', ');
And then, I have the construction of the list:
<?php $urls = explode(',', $usernameid);
$nritems = count ($urls);
$positem = 0;
foreach($urls as $key => $usernameid)
{
echo "<a href="https://www.example.org/something?userid=' . $usernameid .
'">'. $usernameid . '</a>";
if (++$positem != $nritems) { echo ", ";}
}?>
The variable is also used in other parts of the code, so I can't change it. The list is not displaying now.
Any help is appreciated.
Update: the form:
<form action="list.php" method="post" autocomplete="off">
<div id="usrselect">
<label>Select user <input type="text" name="username[]" id="userid" class="typeahead" required/></label>
</div>
<div class="button-section"> <input type="submit" name="List" /></div>
</form>

Answer 1

If you just want to get your quotes right:
echo ''.$usernameid.'';
or
echo "{$usernameid}";
or
echo sprintf('%d', $usernameid, $usernameid);

Answer 2

The working solution, for those who might face the same problem:
<?php $urls = explode(',', $usernameid);
$nritems = count ($urls);
$positem = 0;
$displayuser = array("'", " ");
foreach($urls as $key => $usernameid)
{
echo ''.str_replace($displayuser, "", $usernameid).'';
if (++$positem != $nritems) { echo ", ";}
}?>