Who authored this node?

Say we have a node ID (nid), and we want to know who authored the Drupal node with that ID, and that author is not currently the user that’s logged-in, then we use the Drupal function node_load(). (The companion function to user_load()). The function node_load() either accepts a numerical value which is the nid of the node, OR it accepts an associative array containing information about the node, criteria against which the function will try to find a match, in the database. The function returns a node object. One property of this object is uid, that is, the user ID of the author of the node, and another is name, and that's the name of the author. Say we want to find the e-mail address of the author of node with node ID 25:

/* Using node_load with a node ID parameter */
$node = node_load(25);
/* Then using user_load with the user ID */
$user = user_load(array('uid' => $node->uid));
print t('You may e-mail @name at !mailURL.',  array(
  '@name' => $user->name,
  '!mailURL' => l($user->mail, 'mailto:' . $user->mail),