PHP Foreach loop ending

Inside your foreach, change the echo ","; to following:

if (end($tags) != $var2) {
  echo ",";
}

Doing this will check if you are in the last index by comparing the current index to the last index of the $tags array. Click here to see the PHP wiki on the end() function.

Using this you retrieve the last element with end() and gets is key with key() that you compare with the current key:

foreach($tags as $var1 => $var2) {
    if($_SESSION[$var1]!="off")
    {
        include($var2);
        //needs to include no , character on the last instance.
        if(key(end($tags)) !== $var1)
        {
            echo",";
        }
    }
    else
    {
        echo $var1;
    }
}

This wil help you

 $result = '';
    foreach($tags as $var1 =>$var2) {
        $result .= $var2.',';
    }
    $result = rtrim($result,',');
    echo $result;

Try using the end() function to get the last item:

$last_item = end(array_keys($tags));
foreach($tags as $var1 => $var2) {
    if($_SESSION[$var1]!="off") {
    {
        include($var2);
        if($var1 !== $last_key) {
            echo",";    
        }
    //needs to include no , character on the last instance.
    }
    else
    {
        echo $var1;
    }
}

One way to check the last element and echo comma(,)

$numItems = count($tags );
$i = 0;
foreach($tags  as $var1 =>$var2) {
if($_SESSION[$var1]!="off")
{
include($var2);
if(++$i != $numItems) {
echo ",";
}
}
else
{
echo $var1;
}
}  

First insert all your echo's into string. Then delete final instance of "," with preg_replace function:

$str = preg_replace('/\,$/', '', $str);

Another way is with a counter:

$len = count($tags);  
$iter = 0;
foreach($tags as $var1 => $var2) {
        if($_SESSION[$var1]!="off")
        {
        include($var2);
        if($iter != $len-1)
          echo",";    
        //needs to include no , character on the last instance.
        }
        else
        {
        echo $var1;
        }
      $iter++;
    }

Another way with end() function

foreach($tags as $var1 => $var2) {
    if($_SESSION[$var1]!="off")
    {
    include($var2);
    if (end($tags) != $var2) {
       echo",";    
    //needs to include no , character on the last instance.
    }
    else
    {
    echo $var1;
    }
}