Pavol Lisy wrote:
> On 8/31/17, 20/20 Lab <l...@2020fresno.com> wrote:
>>
>>
>> On 08/31/2017 01:53 AM, Pavol Lisy wrote:
> [...]
>> Valid point, fired up a windows 10 machine and worked as well.
>>
>> Python 3.6.2 (v3.6.2:5fd33b5, Jul 8 2017, 04:14:34) [MSC v.1900 32 bit
>> (Intel)] on win32
>> Type "copyright", "credits" or "license()" for more information.
>> >>> import math
>> >>> math.sqrt(1.3)
>> 1.140175425099138
>> >>>
>>
>> This machine does not have the creators update yet. So there's that.
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>
> Thx! :)
>
> Could somebody help me?
>
> I was trying to call sqrt using ctypes from msvcrt but I am not succesful:
>
> import ctypes
> msc = ctypes.windll.msvcrt
>
> def msqrt(arg):
> s = ctypes.create_string_buffer(100)
> d = ctypes.c_longdouble(arg)
> msc.sprintf(s, b'arg = %g', d)
> print(s.value.decode())
> r = msc.sqrt(d)
> msc.sprintf(s, b'sqrt = %g', r) # r is int so this format is
> wrong I just like to show my intention
> print(s.value.decode())
> print("r = ", r, r.__class__)
>
>>>> msqrt(1.3)
> arg = 1.3
> sqrt = 0
> r = 0 <class 'int'>
>
>>>> msqrt(-1)
> arg = -1
> sqrt = 4.00144e-320 # because wrong format in sprintf
> r = 8099 <class 'int'>
>
> And ->
>
>>>> msc.sqrt.restype
> ctypes.c_long
>
>>>> msc.sqrt.argtypes is None
> True
>
> How to do it properly? Isn't ctypes broken?
I think you have to specify the types yourself:
>>> import ctypes
>>> libm = ctypes.cdll.LoadLibrary("libm.so")
>>> libm.sqrt(42)
0
>>> libm.sqrt.argtypes = [ctypes.c_double]
>>> libm.sqrt.restype = ctypes.c_double
>>> libm.sqrt(42)
6.48074069840786
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