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From: nabbasi@pacbell.net.NOSPAM
Subject: Re: Ada and Java. different behaviour. casting long to int problem.
Date: 1999/06/12
Message-ID: <7jt69l$143f@drn.newsguy.com>#1/1
X-Deja-AN: 488725702
References: <7jt2c0$vrb@drn.newsguy.com>
Organization: Newsguy News Service [http://www.newsguy.com]
Newsgroups: comp.lang.ada,comp.lang.java.programmer
Date: 1999-06-12T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <7jt2c0$vrb@drn.newsguy.com>, nabbasi@pacbell.net says...
 
>In the example, I cast a long integer literal, outside the range
>of an integer, into an integer variable.  Java allows this,
>and produces the wrong result. Ada compiler detect this as an error
>at compile time, and it also detects the same thing at run-time.
>                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

actually that was an error of mine, it did not detect it at run-time,
only at compile time. see below
 
>------------------- ada example 2 -----------------------------
>
>with Ada.Text_Io;         USE Ada.Text_Io;
>
>procedure Test_Cast is
>   N  : Long_Integer;
>   M  : Integer;
>   package Long_Int_Io  is new Ada.Text_Io.Integer_Io(Long_Integer);
>begin
>   Long_Int_Io.Get(N);
>   M := Integer (N);
>
>   Put_Line (   "long n ="  &  Long_integer'Image(N)
>              & "int  m ="  &  Integer'Image(M) );
>end Test_Cast;
>

>$./test_cast                  <--- run
>3200000000
>
>raised ADA.IO_EXCEPTIONS.DATA_ERROR   <-- exception raised
>-------------------------------------------------------------
 
This was an input error which I do not understand now why.

This is a modified Ada program, that shows Ada did not detect at
run-time the overflow (I think may be I am not using the correct 
GNAT flag to enable run-time chekcing? I need to check more on this)

-------------------------------------
with Ada.Text_Io;         USE Ada.Text_Io;

procedure Test_Cast is
   N  : Long_Integer;
   M  : Integer;
   package Long_Int_Io  is new Ada.Text_Io.Integer_Io(Long_Integer);
begin
   N := 2000000000;
   M := Integer (N);
   M := M*2;

   Put_Line (   "long n ="  &  Long_integer'Image(N)
              & "int  m ="  &  Integer'Image(M) );
end Test_Cast;
------------------------------------------
 
$./test_cast
long n = 2000000000int  m =-294967296
                        ^^^^^^^^^^^^^^ 
                            ???
Nasser