PHP Array Looping

I have an array that looks like this:

Array
(
    [0] => stdClass Object
        (
            [user_id] => 10
            [date_modified] => 2010-07-25 01:51:48
        )

    [1] => stdClass Object
        (
            [user_id] => 16
            [date_modified] => 2010-07-26 14:37:24
        )

    [2] => stdClass Object
        (
            [user_id] => 27
            [date_modified] => 2010-07-26 16:49:17
        )

    [3] => stdClass Object
        (
            [user_id] => 79
            [date_modified] => 2010-08-08 18:53:20
        )

)

and what I need to do is print out the user id's comma seperated so:

10, 16, 27, 79

I'm guessing it'd be in a for loop but i'm looking for the most efficient way to do it in 开发者_运维百科PHP

Oh and the Array name is: $mArray

I'm trying the methods below but I keep getting this error: Fatal error: Cannot use object of type stdClass as array in

$length = sizeof($mArray);
sort($mArray);
foreach($mArray as $item)
{
    echo $item['user_id'] . ($item !== $mArray[$length]) ? ', ' : '';
}

Remove the sort if you don't need it in order.

Whenever I need to make a delimited list (in this case by a comma), I start with an array and implode() it with the delimiter. In this case the delimiter would be the comma + the space:

$user_ids = array();
foreach($mArray as $item) {
    $user_ids[] = $item['user_id'];
}
$comma_delimited_list = implode(', ', $user_ids);//magic

$firstTime = true;
foreach($mArray as $k => $cur)
{
    //echo $firstTime ? $firstTime = false : ', '; //this one-liner cna replace the following two, kind of unclear but i like it
    if (!$firstTime) echo ', ';
    else $firstTime = false;
    echo $cur->user_id;
}

This is more fun:

$f = function($a,$b) {$c = $a ? ', ' : ''; return $a . $c . $b->user_id;};
echo array_reduce($f, $mArray, '');

James alludes to using join, which is a good idea and avoids the trailing comma issue

$newArr = array_map(function($x) {return $x->user_id;}, $mArray); //make array of just user-ids
echo join(', ',$newArr);  // implode === join, join is an alias of implode

I'd do it like this:

$output = "";
foreach($mArray as $i => $val) {
    $output .= $val->user_id . ", " ;
}
$output = trim($output, ", ");

Heck, you could probably use join and remove the foreach loop altogether!