code explanation

[jkoracle23]

pls anybody explain this code.(This is from beginning php5,apache, mysql webdevelopment(wrox publication))
function topicReplyBar($topicid,$forumid,$pos="right")
{
$html="<p class=\"buttonBar".$pos."\">";
if($topicid>0)
{
$html.="<a href=\"compose.php?forumid=$forumid&topicid=$topicid&reid=$topicid class=\"buttonlink\">Reply to thread</a>" ;

   }

}

my question in the line that is underlined...what is the purpose of that php variable $pos there in the class .i am unable to understand...
Thank You..🙂😕

[Randy_Jackson]

In this instance, the code is specifying a CSS class for the paragraph, specifically 'buttonBar.right'. In the function, one of the arguments is the variable

$pos 

, which is set to a default of 'right'.

So in theory, if you had different CSS classes set up for left, right and center, you could call the function in this manner:

echo topicReplyBar(13,7,'center')

Where 13 is the topic id, 7 is the forum id, and 'center' is the class for the element.