Wordpress: Removing the last comma for tag list

Question

I've created a custom foreach output that helps give me a tag id per post. I'm using commas to separate each tag. However, the last tag outputs a comma too, like this:

kittens, dogs, parrots, (<-- last comma)

How should I go about revising the foreach output so that the last comma is removed so it displays like this:

kittens, dogs, parrots

Here's the code:

<?php
$posttags = get_the_tags();
if ($posttags) {
    foreach($posttags as $tag) {
        echo '<a href="';
        echo bloginfo(url);
        echo '/?tag=' . $tag->slug . '" class="tag-link-' . $tag->term_id . '">' . $tag->name . '</a>, ';
    }
}
?>

Answer 1

Try something like this?

<?php
$posttags = get_the_tags();
if ($posttags) {
    $loop = 1; // *
    foreach($posttags as $tag) {
        echo '<a href="';
        echo bloginfo(url);
        if ($loop<count($posttags)) $endline = ', '; else $endline = ''; // *
        $loop++ // *
        echo '/?tag=' . $tag->slug . '" class="tag-link-' . $tag->term_id . '">' . $tag->name . '</a>' . $endline;
    }
}
?>

edit or

<?php
$posttags = get_the_tags();
if ($posttags) {
    $tagstr = '';
    foreach($posttags as $tag) {
        $tagstr .= '<a href="';
        $tagstr .= bloginfo(url);
        $tagstr .= '/?tag=' . $tag->slug . '" class="tag-link-' . $tag->term_id . '">' . $tag->name . '</a>';
    }
    $tagstr = substr($tagstr , 0, -2);
    echo $tagstr ;
}
?>