Set value for custom attribute

Question

I have created attribute for products using following code in magento root

require_once('app/Mage.php'); //Path to Magento
umask(0);
Mage::app();
    Mage::app()->setCurrentStore(Mage::getModel('core/store')->load(Mage_Core_Model_App::ADMIN_STORE_ID));
    foreach(Mage::getModel('catalog/product')->getCollection() as $product)
    {
        $num= $product->getId();
       $test=generateEAN($num); //this is the values i have to set for the custom attribute of each product
       $installer = new Mage_Sales_Model_Mysql4_Setup;
       $attribute  = array(
        'type' => 'text',
        'label'=> 'test',
        'input' => 'text',
        'global' => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL,
        'visible' => true,
        'required' => false,
        'user_defined' => true,
        'default' => $test,// i don't know this is the correct way to assign the value to each product
        'group' => "General"
    );

    $installer->addAttribute('catalog_product', 'testing', $attribute);
    $installer->endSetup();

    }

Answer 1

Yes,it works now .Thank you for your comments. I have created attribute first and then edit the code like this .

foreach(Mage::getModel('catalog/product')->getCollection() as $product)
{
      $num= $product->getId();
      $test=generateEAN($num);
      echo $test.'<br>';
      $action = Mage::getModel('catalog/resource_product_action');
      $action->updateAttributes(array($num), array(
    'testing' => $test
));
}