Display a message to the user in Drupal

Question

In the code of my *beautiful_site* module, what are the correct ways to display a message to the user?

Accepted Answer

drupal_set_message(t('Warning, Your article %title was not created right.', array('%title' => $title)), 'error');

Answer

drupal_set_message(t('Warning, Your article ' . $title . ' was not created right.'), 'error');

Answer

drupal_set_message(t("Attention, vous n'avez pas créé correctement l'article " . $title), 'error');

Answer

drupal_set_message(t("Attention, vous n'avez pas créé correctement l'article %title", array('%title' => $title)), 'error');

Answer

drupal_state_message(t('Warning, Your article %title was not created right.', array('%title' => $title)), 'error');

Answer

watchdog_message('beautiful_site', t('Warning, Your article %title was not created right.', array('%title' => $title)), WATCHDOG_ERROR);

Question from the Drupal 7 test