: Issues related to regular and cyclic

Help: Questions about regular and cyclical
$v = "AB1,AB2,AB3,AB4,AB5";
$k = Explode (",", $v);
foreach ($k as $x)
{
$x 1=preg_replace ("|b|", "M", $x);
echo $x 1. ';
$x 1+= $x 1. " /";
}
echo $x 1;
?>

My idea should be this:

(1) AM1->AM2->AM3->AM4->AM5

(2) AM1/AM2/AM3/AM4/AM5

But one effect is not realized, please help. Thank you!

------Solution--------------------
$k = Explode (",", $v)

First argument, one more space


------Solution--------------------

PHP Code

echo str_replace (Array (', ', ' B '), Array (', ', ' m '), $v);
echo str_replace (Array (', ', ' B '), Array ('/', ' m '), $v);
