class EXAMPLE3
   --
   -- To start with NUMBERs, just compile an run it :
   -- 
   --            compile -o example3 -boost example3
   --

creation make

feature

   make is
      local
         n: NUMBER; s: STRING
      do
	 if argument_count = 0 then
	    io.put_string("[
               You are supposed to pass some argument to this command
               in order to compute factorial for this argument.
               As an example, if you pass 50 as an argument, it gives:

                           ]")
	    n := (50).to_number
	 else
	    s := argument(1)
	    if s.is_number then
	       n := s.to_number
	       if not n.is_abstract_integer then
		  io.put_number(n)
		  io.put_string(" : this is not an integer !%N")
		  die_with_code(exit_failure_code)
	       end
	       if n @< 0 then
		  io.put_number(n)
		  io.put_string(" : this is not a positive integer !%N")
		  die_with_code(exit_failure_code)
	       end
	    else
	       io.put_string(s)
	       io.put_string(" : this is not a number !%N")
	       die_with_code(exit_failure_code)
	    end
	 end
	 compute_factorial(n)
      end

   compute_factorial(n: NUMBER) is
      do
	 io.put_character('(')
	 io.put_number(n)
	 io.put_string(").factorial = ")
	 io.put_number(n.factorial)
	 io.put_character('%N')
      end

end -- EXAMPLE3

