User login validation Check In magento

      /*****************************************************
For FrontEnd
  $session=Mage::getSingleton('customer/session', array('name'=>'frontend') );
        if ($session->isLoggedIn()) {
            echo "Welcome, ".$session->getCustomer()->getName();
        } else {
            echo "Not logged in";
        }


For BackEnd

$adminsession = Mage::getSingleton('admin/session', array('name'=>'adminhtml'));

if($adminsession->isLoggedIn()) {
    echo "Welcome Admin";
} else {
    echo "Not logged in";
}