• Sean Eskapp (2/2) Sep 01 2011 Is integer overflow defined (for instance, as being mod 2^size)? Can I
• Timon Gehr (6/8) Sep 01 2011 I am quite sure that all operations are defined as operations on two's
• Sean Eskapp (2/10) Sep 01 2011 Ah, good points, thanks!
• bearophile (4/5) Sep 01 2011 Uhmmmm.
• Timon Gehr (6/11) Sep 02 2011 For unsigned integers it is clearly defined:

Sean Eskapp <eatingstaples gmail.com> writes:

Is integer overflow defined (for instance, as being mod 2^size)? Can I
reliably say that -long.min == 0L?

Timon Gehr <timon.gehr gmx.ch> writes:

On 09/01/2011 06:20 PM, Sean Eskapp wrote:
 Is integer overflow defined (for instance, as being mod 2^size)?

I am quite sure that all operations are defined as operations on two's 
complement integers, which would mean overflow is defined, but I cannot 
find the respective part of the specification...

 Can I reliably say that -long.min == 0L?

Well no, -long.min == long.min .

according to TDPL p53., that fact is defined. (unary minus: -x == ~x+1)

Sean Eskapp <eatingstaples gmail.com> writes:

== Quote from Timon Gehr (timon.gehr gmx.ch)'s article
 On 09/01/2011 06:20 PM, Sean Eskapp wrote:
 Is integer overflow defined (for instance, as being mod 2^size)?

 I am quite sure that all operations are defined as operations on two's
 complement integers, which would mean overflow is defined, but I cannot
 find the respective part of the specification...
  > Can I reliably say that -long.min == 0L?
 Well no, -long.min == long.min .
 according to TDPL p53., that fact is defined. (unary minus: -x == ~x+1)

Ah, good points, thanks!

bearophile <bearophileHUGS lycos.com> writes:

Timon Gehr:

 according to TDPL p53., that fact is defined. (unary minus: -x == ~x+1)

Uhmmmm.

Bye,
bearophile

Timon Gehr <timon.gehr gmx.ch> writes:

On 09/02/2011 02:45 AM, bearophile wrote:
 Timon Gehr:

 according to TDPL p53., that fact is defined. (unary minus: -x == ~x+1)

 Uhmmmm.

 Bye,
 bearophile

For unsigned integers it is clearly defined:

1000... => 0111... => 1000...

And according to TDPL p53: "This manipulation does not raise particular 
questions about the signedness of val".

So, it is guaranteed that it will work for long.min .