

   MMeennuu IInntteerraaccttiioonn FFuunnccttiioonn

        menu(x)

   AArrgguummeennttss::

          x: a character vector of choices

   DDeessccrriippttiioonn::

        `menu' presents the user with a menu of choices
        labelled from 1 to the number of choices.  To exit
        without choosing an item one can select `0'.

   VVaalluuee::

        The number corresponding to the selected item, or 0 if
        no choice was made.

   EExxaammpplleess::

        switch(menu(c("List letters", "List LETTERS")) + 1,
               cat("Nothing done\n"), letters, LETTERS)

