Re: Ada vs Delphi?

[aratel@total.net (Andre Ratel)]

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On Mon, 09 Aug 1999 10:57:51 +0200, Gautier
<gautier.demontmollin@maths.unine.ch> wrote:

>If they have kept compatibility from Turbo Pascal, there is
>a total casting between byte (unsigned_8), short_integer (integer_8),
>word (unsigned_16), integer (integer_16), longint (integer_32)...
>
>The bugs from unsigned <-> signed are the most vicious.

There's also the wrap arounds (so I always keep range checking
enabled.)

>Has this changed in Delphi (read: have they "Adaized" this) ?

Not with Delphi 4 (but version 5 is supposed to get out this 
month :-). Here's from the doc of Delphi 4:

     "If an operand�s type is a subrange of an integer type,
      it is treated as if it were of the integer type."
           (Oplg.pdf - Object Pascal Language Guide, p. 4-7)

     "Performing arithmetic on signed and unsigned Integers
      results in all values being promoted to Int64 to avoid
      potential overflow."
                        (del4new.hlp  -  Compatibility issues)

I just tried this

<<<<<<<<<<
{$RANGECHECK ON}

  var
    n1, n2: shortint; {range: -128 .. 127}
    N: integer; {range: 2147483648 .. 2147483647}

  begin
    n1:= 120;
    n2:= 120;
    N:= n1 + n2;
    Writeln(N);
  end;
>>>>>>>>>>

The result was, appropriately 240.

Now, if I know that n1 and n2 are both in the range -128..127
while their sum is outside this range, I don't understand what's 
wrong with assigning (n1 + n2) to an integer.

	Andre