Inserting commas between city, state, country input depending on which locations are submitted

I have three (optionally entered) post variables: city, state, and country. I'm unsure how to check to see which three are not empty and then insert commas between them accordingly. Someone might only enter a city, enter a city and state, only a city and country, etc. I know t开发者_开发百科here's an easy way of doing this but I'm having trouble doing it without making it many more lines of code than I need. Example:

<?php
    $country = $_POST['country'];
    $state = $_POST['state'];
    $city = $_POST['city'];
    if (!empty($city)){
        $location = $city;
    }
    if (!empty($state) && !empty($city)){
        $location .= ', ' . $state;
    }
    if (!empty($ state) ** !empty$country)){
        $location .=  ', '. $country;
    }

    echo $location;
?>

$location = array();
if(!empty($_POST['country'])) $location['country'] = $_POST['country'];
if(!empty($_POST['state'])) $location['state'] = $_POST['state'];
if(!empty($_POST['city'])) $location['city'] = $_POST['city'];

$location = implode(', ', $location);

Security Precautions

1. If you are using this to generate database queries, please at least use mysql_real_escape_string() (e.g. mysql_real_escape_string($_POST['country'])), unless you are using parametriezed queries (e.g. PDO or MySQLi).

2. If you are outputting the string to the user use htmlentities() (e.g. htmlentities($_POST['country'])).

$loc = array($_POST['country'], $_POST['state'], $_POST['city']);
echo implode(",", $loc);