Integer Overflow

Bjorn Pettersen BPettersen at NAREX.com
Tue Nov 27 18:49:44 CET 2001


> From: Hans Nowak [mailto:wurmy at earthlink.net] 
> 
> Ursus Horibilis wrote:
> > 
> > Is there a way to force the Python run time system to 
> ignore integer 
> > overflows?  I was trying to write a 32-bit Linear 
> Congruential Pseudo 
> > Random Number Generator
> 
> Say what?
> 
> > and got clobbered
> > the first time an integer product or sum went over the 32-bit limit.
> 
> Use longs:
> 
> >>> 2**100
> Traceback (most recent call last):
>   File "<pyshell#0>", line 1, in ?
>     2**100
> OverflowError: integer exponentiation
> >>> 2L**100
> 1267650600228229401496703205376L
> >>> 
> 
> A long integer in Python is simply created by appending an 
> "L" to the number, e.g. 2 (normal integer) vs. 2L (long).

And, if you want the result to be in the 32 bit ring, make sure you take
the answer modulo 2L**32...

-- bjorn




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