CODEWITHSUNDEEP
pythonctypesanaconda
user391339
user391339

Reputation: 8775

Why is my ctypes long size 4 and not size 8 using 64 bit python?

Downstream of this I am getting an error Python int too large to convert to C long, which led me to suspect that somehow ctypes long was too small - size 4 and not 8.

I tested this and it was indeed the case. Yet, I am using Python 2.7 64 bit (Anaconda).

import ctypes as C
import os
import platform
import numpy as np

print "Python Platform Architecture: ", platform.architecture()[0]
print "Size of ctypes long: ", (C.sizeof(C.c_long))

This is the output:

Python Platform Architecture:  64bit
Size of ctypes long:  4

Upvotes: 2

Views: 998

Answers (1)

mipadi
mipadi

Reputation: 410762

A long is only guaranteed to be at least 32 bits wide, so on some systems, ctypes.c_long is only 32 bits. In particular, I believe on 64-bit Windows, ctypes.c_long is only 32 bits wide. If it must be 64 bits wide, use ctypes.c_int64 instead.

Upvotes: 6

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