ctypes

问题 I am no stranger to the python ctypes module, but this is my first attempt at combining C++, C and Python all in one code. My problem seems to be very similar to Seg fault when using ctypes with Python and C++, however I could not seem to solve the problem in the same way. I have a simple C++ file called Header.cpp : #include <iostream> class Foo{ public: int nbits; Foo(int nb){nbits = nb;} void bar(){ std::cout << nbits << std::endl; } }; extern "C" { Foo *Foo_new(int nbits){ return new Foo

问题 Python provides the following three modules that deal with C types and how to handle them: struct for C structs array for arrays such as those in C ctypes for C functions, which necessarily entails dealing with C’s type system While ctypes seems more general and flexible (its main task being “a foreign function library for Python”) than struct and array , there seems to be significant overlap in functionality between these three modules when the task is to read binary data structures. For

问题 I am trying to load a dll form python code with ctypes and it raised an error. my python code: import ctypes from ctypes import * hllDll = ctypes.WinDLL ("c:\\Users\\saar\\Desktop\\pythonTest\\check.dll") and this raised error: Traceback (most recent call last): File "C:\AI\PythonProject\check.py", line 5, in <module> hllDll = ctypes.WinDLL("c:\\Users\\saar\\Desktop\\pythonTest\\check.dll") File "C:\Python27\lib\ctypes\__init__.py", line 365, in __init__ self._handle = _dlopen(self._name,

问题 Related to my other question How can I get the address (acctual function pointer) to a CFuncType object? addressof() does not report the correct address. C code: extern "C" _declspec(dllexport) int addr(int (*func)()) { int r = (int)func; return r; } Python code: def test(): return 42 t = CFUNCTYPE(c_int) f = t(test) print addressof(f) print dll.addr(f) Output: 7030864 3411932 trying to call *(7030864) from C causes a crash, but calling *(3411932) works as expected. What's wrong with

问题 Related to my other question How can I get the address (acctual function pointer) to a CFuncType object? addressof() does not report the correct address. C code: extern "C" _declspec(dllexport) int addr(int (*func)()) { int r = (int)func; return r; } Python code: def test(): return 42 t = CFUNCTYPE(c_int) f = t(test) print addressof(f) print dll.addr(f) Output: 7030864 3411932 trying to call *(7030864) from C causes a crash, but calling *(3411932) works as expected. What's wrong with

问题 I have a foreign C library which uses utf-16 in API: as function arguments, return values and structure members. On Windows its OK with ctypes.c_wchar_p, but under OSX ctypes uses UCS-32 in c_wchar and I could not find the way to support utf-16. Here is my research: Use _SimpleCData subclassing to redefine _check_retval_. it allows a transparent conversion of utf-16 to Python string. can be placed as C structure member But it doesn't allow to handle strings as arguments, its from_param()

问题 I have a foreign C library which uses utf-16 in API: as function arguments, return values and structure members. On Windows its OK with ctypes.c_wchar_p, but under OSX ctypes uses UCS-32 in c_wchar and I could not find the way to support utf-16. Here is my research: Use _SimpleCData subclassing to redefine _check_retval_. it allows a transparent conversion of utf-16 to Python string. can be placed as C structure member But it doesn't allow to handle strings as arguments, its from_param()

问题 I have a foreign C library which uses utf-16 in API: as function arguments, return values and structure members. On Windows its OK with ctypes.c_wchar_p, but under OSX ctypes uses UCS-32 in c_wchar and I could not find the way to support utf-16. Here is my research: Use _SimpleCData subclassing to redefine _check_retval_. it allows a transparent conversion of utf-16 to Python string. can be placed as C structure member But it doesn't allow to handle strings as arguments, its from_param()

问题 *I am trying to display preview from webcam captured using v4l. Here is an idea of how the code looks like: from ctypes import * from v4l2 import * from Image import fromstring from Tkinter import Tk, Label from ImageTk import PhotoImage from ctypes.util import find_library libc = CDLL(find_library('c')) posix_memalign = libc.posix_memalign getpagesize = libc.getpagesize device_name = '/dev/video0' ps = preview_settings = { 'width': 320, 'height': 240, 'pixformat': 'RGB', } PIX_FMT = V4L2_PIX

问题 *I am trying to display preview from webcam captured using v4l. Here is an idea of how the code looks like: from ctypes import * from v4l2 import * from Image import fromstring from Tkinter import Tk, Label from ImageTk import PhotoImage from ctypes.util import find_library libc = CDLL(find_library('c')) posix_memalign = libc.posix_memalign getpagesize = libc.getpagesize device_name = '/dev/video0' ps = preview_settings = { 'width': 320, 'height': 240, 'pixformat': 'RGB', } PIX_FMT = V4L2_PIX