New submission from Alex Wang:
- Python Version
Python 3.5.2
- Issue
I found that the c_wchar_p and c_char_p return results behaves different from
what it is based on ctypes doc. From the ctypes doc of Python 3.5:
>>> c_wchar_p("Hello, World")
c_wchar_p('Hello, World')
It return the ctypes string. But my results of execute the same cmd in
Python3.5 console:
>>> from ctypes import *
>>> c_wchar_p("Hello, World")
c_wchar_p(1374004842736)
>>> c_wchar_p("Hello, World")
c_wchar_p(1374004841680)
>>> c_wchar_p("Hello, World")
c_wchar_p(1374004842736)
So seems like the orignial string part replaced by memory address. Digged in
more, and found out if it is Python 2.x, then the return shows the string like
the Python 3.5 ctypes doc shows. But in Python 3.x, it always return these
numbers. Checked on multiple PCs, all seen the same thing. And understood the
part that, we can use .value to return the original string. Same thing observed
on create_string_buffer() and create_unicode_buffer(). Meanwhile, for other
data types like c_int(), c_bool, c_void_p etc., not see this.
- Question
Can anyone provide a explaination about this behavior of ctypes?
And is there any way to fix the Python3.x return resuls as the same as what is
doc wrote? (It seems that when it behave like this, I had issue with passing
Python string to C function, when I interact with a C DLL.)
- Repro
This can be reproduce in python.org/shell easily.
Thanks a lot in advance~
----------
components: ctypes
messages: 280869
nosy: Alex Wang
priority: normal
severity: normal
status: open
title: Python 3.x ctypes c_wchar_p return is different from official
documentation example
type: behavior
versions: Python 3.5
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue28698>
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