Factorial in Ada

Factorial

in Ada

Welcome to the Factorial in Ada page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

with Ada.Text_IO;      use Ada.Text_IO;
with Ada.Command_Line; use Ada.Command_Line;

procedure Factorial is

   procedure Print_Usage is
   begin
      Put_Line ("Usage: please input a non-negative integer");
   end Print_Usage;

   function Fact (N : Natural) return Natural is
      Result : Natural := 1;
   begin
      for I in 2 .. N loop
         Result := Result * I;
      end loop;
      return Result;
   end Fact;

   Max_Allowed : constant Natural := 12; -- Fact (13) > Natural'Last

begin
   if Argument_Count /= 1 then
      Print_Usage;
      return;
   end if;

   declare
      N : Natural;
   begin
      begin
         N := Natural'Value (Argument (1));
      exception
         when Constraint_Error =>
            Print_Usage;
            return;
      end;

      if N > Max_Allowed then
         Print_Usage;
         return;
      end if;

      Put_Line (Natural'Image (Fact (N)));

   end;

end Factorial;

Factorial in Ada was written by:

• Ștefan-Iulian Alecu

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

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How to Run the Solution

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