期望传递一个变量：

$img= mysql_real_escape_string(end(explode('/',$_POST['img'])));

the statement expects a variable to be passed, any idea on how to use both the end and explode functions?

the statement expects a variable to be passed so why don't you pass it a variable reference to the end function ?

$images = explode('/',$_POST['img']);
$lastImage = end($images);
$img = mysql_real_escape_string($lastImage);