-- string_IO.adb  a sample to demonstrate input and output of
--                string type data, and using the  if-then-else  structure
-- 
--   The names of four transactions are defined as an Ada strings.
--   i.e. a user chosen set of english words that can be input,
--   output, and recognized. This is an alternative to enumeration types.

--   Bank_Transactions  can be  OPEN   CLOSE   DEPOSIT    WITHDRAW

with Ada.Text_IO ; use Ada.Text_IO ;

procedure String_IO is

  subtype Transactions is String ( 1 .. 8 ) ;
  Transaction : Transactions ;

begin

  loop

    Put_Line ( " Enter transaction. " ) ;
    Get ( Transaction ) ;
    Put ( Transaction ) ;
    Put_Line ( " transaction being processed" ) ;

    if Transaction = "OPEN    " then     -- note filled in spaces
      PUT_Line ( " opening " ) ;
    elsif Transaction = "CLOSE   " then  -- a short string would have ASCII nul
      Put_Line ( " closing " ) ;
    elsif Transaction = "DEPOSIT " then
      Put_Line ( " depositing " ) ;
    elsif Transaction = "WITHDRAW" then  -- this fills string, determines length
      Put_Line ( " withdrawing " ) ;
    else
      Put_Line ( " not a transaction " ) ;
    end if ;

  end loop ;

  -- make a string literal fit where it is to be stored, 1..8
  Transaction := "THE_" & ( 5..Transactions'Last => ' ' ) ;
  Transaction := "THE_" & ( 1..4 => ' ' ) ;

end String_IO ;

--  Enter transaction.                           data printed as entered 
-- OPEN     transaction being processed
--  opening 
--  Enter transaction. 
-- DEPOSIT  transaction being processed
--  depositing 
--  Enter transaction. 
-- WITHDRAW transaction being processed
--  withdrawing 
--  Enter transaction. 
-- CLOSE    transaction being processed
--  closing 
--  Enter transaction. 
-- open     transaction being processed
--  not a transaction 
--  Enter transaction. 
-- JUNK     transaction being processed
--  not a transaction 
--  Enter transaction. 
-- raised ADA.IO_EXCEPTIONS.END_ERROR