python调用c/c++方式示例（修改整理）

Python是解释性语言, 底层就是用c实现的, 所以用python调用C是很容易的, 下面就总结一下各种调用的方法, 给出例子, 所有例子都在ubuntu9.10, python2.6下试过.

 

1. Python 调用 C (base)

想在python中调用c函数, 如这儿的fact

#include <Python.h>int fact(int n){  if (n <= 1)    return 1;  else    return n * fact(n - 1);}PyObject* wrap_fact(PyObject* self, PyObject* args){  int n, result;  if (! PyArg_ParseTuple(args, "i:fact", &n))    return NULL;  result = fact(n);  return Py_BuildValue("i", result);}static PyMethodDef exampleMethods[] ={  {"fact", wrap_fact, METH_VARARGS, "Caculate N!"},  {NULL, NULL}};void initexample(){  PyObject* m;  m = Py_InitModule("example", exampleMethods);}

 

把这段代码存为wrapper.c, 编成so库,

gcc -fPIC wrapper.c -o example.so -shared  -I/usr/include/python2.6 -I/usr/lib/python2.6/config

 

然后在有此so库的目录, 进入python, 可以如下使用

import exampleexample.fact(4)

 

2. Python 调用 C++ (base)

在python中调用C++类成员函数, 如下调用TestFact类中的fact函数,

#include <Python.h>class TestFact{    public:    TestFact(){};    ~TestFact(){};    int fact(int n);};int TestFact::fact(int n){  if (n <= 1)    return 1;  else    return n * (n - 1);}int fact(int n){    TestFact t;    return t.fact(n);}PyObject* wrap_fact(PyObject* self, PyObject* args){  int n, result;  if (! PyArg_ParseTuple(args, "i:fact", &n))    return NULL;  result = fact(n);  return Py_BuildValue("i", result);}static PyMethodDef exampleMethods[] ={  {"fact", wrap_fact, METH_VARARGS, "Caculate N!"},  {NULL, NULL}};extern "C"             //不加会导致找不到initexamplevoid initexample(){  PyObject* m;  m = Py_InitModule("example", exampleMethods);}

 

把这段代码存为wrapper.cpp, 编成so库,

g++ -fPIC wrapper.cpp -o example.so -shared -I/usr/include/python2.6 -I/usr/lib/python2.6/config

 

然后在有此so库的目录, 进入python, 可以如下使用

import exampleexample.fact(4)

 

3. Python 调用 C++ (Boost.Python)

Boost库是非常强大的库, 其中的python库可以用来封装c++被python调用, 功能比较强大, 不但可以封装函数还能封装类, 类成员.

http://dev.gameres.com/Program/Abstract/Building%20Hybrid%20Systems%20with%20Boost_Python.CHN.by.JERRY.htm

首先在ubuntu下安装boost.python, apt-get install libboost-python-dev

#include <boost/python.hpp>char const* greet(){   return "hello, world";}BOOST_PYTHON_MODULE(hello){    using namespace boost::python;    def("greet", greet);}

把代码存为hello.cpp, 编译成so库

g++ hello.cpp -o hello.so -shared -I/usr/include/python2.5 -I/usr/lib/python2.5/config -lboost_python-gcc42-mt-1_34_1

 

此处python路径设为你的python路径, 并且必须加-lboost_python-gcc42-mt-1_34_1, 这个库名不一定是这个, 去/user/lib查

 

然后在有此so库的目录, 进入python, 可以如下使用

>>> import hello>>> hello.greet()'hello, world'

 

4. python 调用 c++ (ctypes)

ctypes is an advanced ffi (Foreign Function Interface) packageforPython 2.3 and higher. InPython 2.5 it is alreadyincluded.

ctypes allows to call functions in dlls/shared libraries and hasextensive facilities to create, access and manipulate simple andcomplicated C data types in Python - in other words: wraplibraries in pure Python. It is even possible to implement Ccallback functions in pure Python.

http://python.net/crew/theller/ctypes/

 

#include <Python.h>class TestFact{    public:    TestFact(){};    ~TestFact(){};    int fact(int n);};int TestFact::fact(int n){  if (n <= 1)    return 1;  else    return n * (n - 1);}extern "C"int fact(int n){    TestFact t;    return t.fact(n);}

将代码存为wrapper.cpp不用写python接口封装, 直接编译成so库,

g++ -fPIC wrapper.cpp -o example.so -shared -I/usr/include/python2.6 -I/usr/lib/python2.6/config

 

进入python, 可以如下使用

>>> import ctypes
>>> pdll = ctypes.CDLL('/home/ubuntu/tmp/example.so')
>>> pdll.fact(4)
12