2 + 2 = 5

Wed Jul 4 16:37:16 EDT 2012

Am 04.07.2012, 21:37 Uhr, schrieb Paul Rubin <phr-2012 at nightsong.com>:
> I just came across this (https://gist.github.com/1208215):
>> import sys
> import ctypes
> pyint_p = ctypes.POINTER(ctypes.c_byte*sys.getsizeof(5))
> five = ctypes.cast(id(5), pyint_p)
> print(2 + 2 == 5) # False
> five.contents[five.contents[:].index(5)] = 4
> print(2 + 2 == 5) # True (must be sufficiently large values of 2 
> there...)
>> Heh. The author is apparently anonymous, I guess for good reason.

Neat.
Playing with it, i'm wondering:
This:
	import sys
	import ctypes
	pyint_p = ctypes.POINTER(ctypes.c_byte*sys.getsizeof(5))
	five = ctypes.cast(id(5), pyint_p)
	five.contents[five.contents[:].index(5)] = 4
	print ( 2 + 2 == 5 )
	print 5
	print 5 - 2
put into a script and run prints:
	True
	4
	3
while entered at the python prompt it prints:
	True
	4
	2
??
Regards,
Michael