Re: 2 + 2 = 5

[Michael Ross]

Am 04.07.2012, 21:37 Uhr, schrieb Paul Rubin <phr-2...@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
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