-- File: ExceptionDemo.adb
-- Smorgasbord: Includes raising, catching, and declaring exceptions

with Ada.Text_IO, Ada.Integer_Text_IO;
use  Ada.Text_IO, Ada.Integer_Text_IO;

procedure ExceptionDemo is

   -- Demo constraint error. 
   -- For Exceptions in the language: 
   --		http://archive.adaic.com/standards/83lrm/html/lrm-11-01.html
   procedure Divide_By_Zero(Count : Integer) is
      Divide_Result : Integer;
   begin
      Put("Count is");
      Put(Count, 3);
      Put(" and the answer is");
      Divide_Result := 25 / (Count - 4);
      Put(Divide_Result, 4);
      New_Line;
   exception
      when Constraint_Error => Put_Line(" Divide by zero occurred");
   end Divide_By_Zero;

   -- Demo creating and raising an exception.
   procedure Raise_An_Error(Count : Integer) is
      My_Own_Error : exception;	-- Declare it
      Another_Result : Integer;
   begin
      Put("Count is");
      Put(Count, 3);
      Another_Result := 35 / (Count - 6);  -- untested divide by zero
      if Count = 3 then
         raise My_Own_Error;	-- Raise it
      end if;
      Put_Line(" and is a legal value");
   exception			-- Catch it
      when My_Own_Error => Put_Line(" My own error occurred");
   end Raise_An_Error;

begin
   for Count in 1..7 loop
      Divide_By_Zero(Count);
      Raise_An_Error(Count);	-- Will crash program when Count is 6
   end loop;
   Put_Line("End of program.");
   exception
      when Constraint_Error => Put(" Constraint error detected at");
                               Put_Line(" the main program level.");
                               Put_Line("Program terminated.");
end ExceptionDemo;