change_calculator.adb.npp

with Ada.Text_IO;
with Ada.Float_Text_IO;
with Ada.IO_Exceptions;
with Ada.Integer_Text_IO;
use Ada;

procedure Change_Calculator is
   type Money is delta 0.01 digits 10;
   Input_Amount : Money := 0.0;
   package Money_IO is new Text_IO.Decimal_IO(Money);

   type Currency_Denomination is record
      Name : String(1..10);
      Value : Money;
   end record;

   Currency_Names  : array (1..10) of Currency_Denomination;
   Currency_Counts : array (1..10) of Integer := (others=>0);
   Currency_Index  : Integer range 1..10;

   procedure Get_Money_Prompt(Amount: out Money) is
      Response : String(1..20);
      Last     : Natural;
   begin
      loop
         declare
         begin
            Text_IO.Put("amount: ");
            Text_IO.Flush;
            Text_IO.Get_Line(Response, Last);
            -- try to convert string input to money type
            Amount := Money'Value(Response(1 .. Last));
            -- quit the loop if the money converted
            exit;
         exception
            when Constraint_Error =>
               Text_IO.Put_Line("ERROR: bad money format");
         end;
      end loop;
   end Get_Money_Prompt;

begin
   Currency_Names := (("Penny     ", 0.01),
                      ("Nickle    ", 0.05),
                      ("Dime      ", 0.10),
                      ("Quarter   ", 0.25),
                      ("Dollar    ", 1.00),
                      ("5 Dollar  ", 5.00),
                      ("10 Dollar ", 10.00),
                      ("20 Dollar ", 20.00),
                      ("50 Dollar ", 50.00),
                      ("100 Dollar", 100.00));

   -- read money amount from the user
   Get_Money_Prompt(Input_Amount);

   -- calculate needed currency
   for I in Currency_Names'Range loop
      -- calculate inverse of index to count backwords
      Currency_Index := (Currency_Names'Length-I)+1;
      while Input_Amount >= Currency_Names(Currency_Index).Value loop
         Input_Amount := Input_Amount - Currency_Names(Currency_Index).Value;
         -- increment currency useage in array
         Currency_Counts(I) := Currency_Counts(I) + 1;
      end loop;
   end loop;

   -- display needed currency
   for I in Currency_Counts'Range loop
      Currency_Index := (Currency_Names'Length-I)+1;
      -- do not display unused currency
      if Currency_Counts(Currency_Index) /= 0 then
        Text_IO.Put(Currency_Names(I).Name & " ");
        Integer_Text_IO.Put(Currency_Counts(Currency_Index));
        Text_IO.New_Line;
      end if;
   end loop;

end Change_Calculator;