将 C++ 函数导入 Python 程序
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Import C++ function into Python program
提问by Nick
I'm experimenting with python functions right now. I've found a way to import python functions into c/c++ code, but not the other way around.
我现在正在试验 python 函数。我找到了一种将 python 函数导入 c/c++ 代码的方法，但反过来不行。
I have a c++ program written and it has a certain function in it. I'd like to "import" the compiled c++ program into my python script and call the c++ function.
我写了一个 C++ 程序，它有一个特定的功能。我想将编译后的 c++ 程序“导入”到我的 python 脚本中并调用 c++ 函数。
For simplicity, say the c++ function is as simple as:
为简单起见，假设 c++ 函数很简单：
int square(x)
{
return x*x;
}
and the compiled program is named Cprog.
编译后的程序名为Cprog。
I'd like my python script to be something like:
我希望我的 python 脚本类似于：
import Cprog
print Cprog.square(4)
Is this possible? I've searched the internet to no avail and I'm hoping one of you gurus might have a clever way of going about this...
这可能吗？我在互联网上搜索无果，我希望你们中的一位大师可能有一个聪明的方法来解决这个问题......
回答by kichik
If you build your program as a shared library/DLL, you could use ctypes to call it.
如果您将程序构建为共享库/DLL，则可以使用 ctypes 来调用它。
import ctypes
print ctypes.windll.cprog.square(4) # windows
print ctypes.CDLL('cprog.so').square(4) # linux
回答by Anthony
You want to extendpython with a C/C++ module. The following Python documentation is a good place to start reading: http://docs.python.org/extending/extending.html
你想用 C/C++ 模块扩展python。以下 Python 文档是开始阅读的好地方：http: //docs.python.org/extending/extending.html
回答by DaedalusFall
You need to create a python module with that function in it. There are three main ways:
您需要创建一个包含该函数的 python 模块。主要有以下三种方式：
- Using Swig - this reads your c code and creates a python module from it.
- Hand coded using the python c api.
- Using Boost::Python (often the easiest way).
- 使用 Swig - 这会读取您的 c 代码并从中创建一个 python 模块。
- 使用 python c api 手工编码。
- 使用 Boost::Python（通常是最简单的方法）。
This pdfcovers 1 and 2. This pagewill tell you how to use Boost::Python.
该 pdf涵盖 1 和 2。此页面将告诉您如何使用 Boost::Python。
You cannot (easily) use a function that is in a c/c++ program - it must be in a static library (which you can also link your c/c++ program against).
您不能（轻松）使用 ac/c++ 程序中的函数 - 它必须位于静态库中（您也可以将您的 c/c++ 程序链接到该库中）。
EDIT - CythonIs also worth a mention.
编辑 - Cython也值得一提。
回答by Jonathan Sternberg
There are a lot of different ways to wrap C++ code to be used in Python. Most are listed on the Python wiki here.
有很多不同的方法来包装要在 Python 中使用的 C++ 代码。大多数都列在此处的 Python wiki 上。
I've found a decently easy way to automate it is to use py++to automatically generate the wrappers, then compile the generated files. But this is more appropriate for larger projects where wrapping everything by hand is just not very feasible and would cause a maintenence nightmare.
我发现一种相当简单的自动化方法是使用py++自动生成包装器，然后编译生成的文件。但这更适合大型项目，因为手动包装所有东西不太可行，并且会导致维护噩梦。
回答by dolby
Here is a little working completion of the simple example above. Although the thread is old, I think it is helpful to have a simple all-embracing guide for beginners, because I also had some problems before.
这是上面简单示例的一些工作完成。虽然线程老了，但是我觉得给初学者一个简单的包罗万象的指南还是有帮助的，因为我之前也遇到过一些问题。
function.cpp content (extern "C" used so that ctypes module can handle the function):
function.cpp 内容（使用 extern "C" 以便 ctypes 模块可以处理该功能）：
extern "C" int square(int x)
{
return x*x;
}
wrapper.py content:
wrapper.py 内容：
import ctypes
print(ctypes.windll.library.square(4)) # windows
print(ctypes.CDLL('./library.so').square(4)) # linux or when mingw used on windows
Then compile the function.cpp file (by using mingw for example):
然后编译 function.cpp 文件（例如使用 mingw）：
g++ -shared -c -fPIC function.cpp -o function.o
Then create the shared object library with the following command (note: not everywhere are blanks):
然后使用以下命令创建共享对象库（注意：并非处处都是空白）：
g++ -shared -Wl,-soname,library.so -o library.so function.o
Then run the wrapper.py an the program should work.
然后运行 wrapper.py 程序应该可以工作。
