From: Charles Oliver Nutter <headius@...>
Date: 2009-10-07T14:19:41+09:00
Subject: Re: Overflow behavior

On Tue, Sep 15, 2009 at 8:07 AM, Colin Bartlett <colinb2r@googlemail.com> wrote:
> JRuby 1.3.1 JIRB:
> n = if RUBY_PLATFORM.downcase == "java" then 63 else 30 end  #=> 63
> nn = 2 ** n - 1 ; "#{nn.class}  #{nn}"  #=> Fixnum   9223372036854775807
> nn = -nn        ; "#{nn.class}  #{nn}"  #=> Fixnum  -9223372036854775807
> nn = 2 ** n     ; "#{nn.class}  #{nn}"  #=> Bignum   9223372036854775808
> nn = -nn        ; "#{nn.class}  #{nn}"  #=> Fixnum  -9223372036854775808
> nn = 2 ** n + 1 ; "#{nn.class}  #{nn}"  #=> Bignum   9223372036854775809
> nn = -nn        ; "#{nn.class}  #{nn}"  #=> Bignum  -9223372036854775809

JRuby Fixnums are always 64-bit(ish) and the rollover point reflects that.

- Charlie