python与c ++使用ctypes

问题描述

因为我还是新的，我面临一些问题，这里是我的C ++代码：

As I'm still new to this, I'm facing some problems, here's my C++ code:

#include <python.h>

#define DLLEXPORT extern "C" __declspec(dllexport)

DLLEXPORT PyObject *Add(PyObject *pSelf, PyObject *pArgs)
{
    int s,d;
    if(!PyArg_ParseTuple(pArgs, "ii" , &s, &d))
    {
        PyErr_SetString(PyExc_TypeError,
                "Add() invalid parameter");
        return NULL;
    }

    return Py_BuildValue("i", s + d);

}

而Python代码：

import ctypes

MyDll = ctypes.cdll.LoadLibrary(r"PyToCppTest.dll")

jj = MyDll.Add(1,2)

我在运行上述Python代码时遇到错误：

I get an error when I run the above Python code:

$ b b

我想传递数据，而不将其转换，从Python到C ++，然后在C ++中转换。

I want to pass the data, without converting it, from Python to C++, then convert it inside C++.

推荐答案

你的代码有一些错误。首先，合适的include是：

There are a few things that are wrong with your code. First and foremost, the proper include is:

#include <Python.h>

注意资本 P 。你可能在Windows上，但是这不会在没有资本P的Linux上工作。

Note the capital P. You're probably on Windows, but this wouldn't work on Linux without the capital P.

此外，我没有看到 * pSelf 指针，你应该摆脱它：

Also, I don't see the point of the *pSelf pointer in your function declaration, you should get rid of it:

PyObject *Add(PyObject *pArgs)

现在，你的主要问题是：

Now, your main problem is this:

MyDll.Add(1,2)

$ b b

...不用元组调用 MyDll.Add 。它使用两个整数参数 1 和 2 调用它。如果你想传递一个元组，你可以：

...does not call MyDll.Add with a tuple. It calls it with two integer arguments, 1 and 2. If you want to pass a tuple, you'd do:

MyDll.Add((1,2))

然而，Python的ctypes不知道该怎么做（通常接受整数参数）需要告诉它 Add 实际上想要一个元组，并返回一个Python对象：

However, Python's ctypes won't know what to do with this (it normally accepts integer arguments), so you'll need to tell it that Add actually wants a tuple, and returns a Python object:

import ctypes

MyDll = ctypes.cdll.LoadLibrary("PyToCppTest.dll")
MyCFunc = ctypes.PYFUNCTYPE(
    ctypes.py_object,     # return val: a python object
    ctypes.py_object      # argument 1: a tuple
)
MyFunc = MyCFunc(('Add', MyDll))

jj = MyFunc((1,2))

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