From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on
	ip-172-31-74-118.ec2.internal
X-Spam-Level: 
X-Spam-Status: No, score=-0.5 required=3.0 tests=BAYES_05,MSGID_SHORT
	autolearn=no autolearn_force=no version=3.4.5-pre1
Date: 7 Feb 93 00:28:00 GMT
From: ucsbcsl!lemon.ucsb.edu@ucbvax.Berkeley.EDU  (Maxwell Lee)
Subject: question about the fate of input stream after DATA_ERROR
Message-ID: <7600@ucsbcsl.ucsb.edu>
List-Id: <comp.lang.ada>

Hi, I have some ADA code which produces a strange result I can't understand
why.  I'm wondering if someone out there in ADA-land can help me.

I have the following code:

                   type OPCODE is (I, S, Q, X);
                   CODE: OPCODE;
-------------------------------------------------
(in my main program)
         with TEXT_IO; use TEXT_IO;
         with INTEGER_IO; use INTEGER_IO;
         package OPCODE_IO is new ENUMERATION_IO(OPCODE); use OPCODE_IO;
--------------------------------------------------
                   
I simply want to perform a            GET(CODE);
from standard-input.

When I enter an "i", "s", "q", "x", "I", "S", "Q", or "X" the command
works fine.

When I enter a number, say "1", a DATA_ERROR is raised, but the "1" is
left in the input stream (input buffer).

When I enter a character that's not an OPCODE, say an "m", a DATA_ERROR is
raised, but the "m" is removed from the input stream (input buffer) !!!

I understand why both a "1" or an "m" will produce DATA_ERROR, but
I don't understand why "1" will be left in the input stream, but "m"
will be removed from the input stream.  I assumed that in both cases
it would be left in the input stream.  Can someone help me?
Thank you.

**********************************************************************
"Mongo don't know .... Mongo only pawn in game of life."
(From the movie "Blazing Saddles")

maxwell@cs.ucsb.edu
**********************************************************************