Linux下Python与C++混合编程

最近在做一个CUDA的项目,记录下学习心得.

系统

Linux 3.11.0-19-generic #33-Ubuntu x86_64 GNU/Linux

C++调用Python

Python模块代码:

#!/usr/bin/python
#Filename:TestModule.py
def Hello(s):
    print "Hello World"
    print s

def Add(a, b):
    print 'a=', a
    print 'b=', b
    return a + b

class Test:
    def __init__(self):
        print "Init"
    def SayHello(self, name):
        print "Hello,", name
        return name

C++代码:

#include<iostream>
#include<Python.h>
using namespace std;
int main(int argc, char* argv[])
{
    //初始化python
    Py_Initialize();

    //直接运行python代码
    PyRun_SimpleString("print 'Python Start'");

    //引入当前路径,否则下面模块不能正常导入
    PyRun_SimpleString("import sys");  
    PyRun_SimpleString("sys.path.append('./')");  

    //引入模块
    PyObject *pModule = PyImport_ImportModule("TestModule");
    //获取模块字典属性
    PyObject *pDict = PyModule_GetDict(pModule);

    //直接获取模块中的函数
    PyObject *pFunc = PyObject_GetAttrString(pModule, "Hello");

    //参数类型转换，传递一个字符串。将c/c++类型的字符串转换为python类型，元组中的python类型查看python文档
    PyObject *pArg = Py_BuildValue("(s)", "Hello Charity");

    //调用直接获得的函数，并传递参数
    PyEval_CallObject(pFunc, pArg);

    //从字典属性中获取函数
    pFunc = PyDict_GetItemString(pDict, "Add");
    //参数类型转换，传递两个整型参数
    pArg = Py_BuildValue("(i, i)", 1, 2);

    //调用函数，并得到python类型的返回值
    PyObject *result = PyEval_CallObject(pFunc, pArg);
    //c用来保存c/c++类型的返回值
    int c;
    //将python类型的返回值转换为c/c++类型
    PyArg_Parse(result, "i", &c);
    //输出返回值
    printf("a+b=%d\n", c);

    //通过字典属性获取模块中的类
    PyObject *pClass = PyDict_GetItemString(pDict, "Test");

    //实例化获取的类
    PyObject *pInstance = PyInstance_New(pClass, NULL, NULL);
    //调用类的方法
    result = PyObject_CallMethod(pInstance, "SayHello", "(s)", "Charity");
    //输出返回值
    char* name=NULL;
    PyArg_Parse(result, "s", &name);
    printf("%s\n", name);

    PyRun_SimpleString("print 'Python End'");

    //释放python
    Py_Finalize();
    getchar();
    return 0;
}

编译:

g++ -I/usr/include/python2.7 PythonWithCpp.cpp -lpython2.7

运行结果:

Python Start
Hello World
Hello Charity
a= 1
b= 2
a+b=3
Init
Hello, Charity
Charity
Python End

Python调用C++

C++代码:

//用C++必须在函数前加extern "C"
extern "C" int Add(int a,int b)
{
    return a+b;
}

编译:

g++ -c -fPIC LibPythonTest.cpp
g++ -shared LibPythonTest.o -o LibPythonTest.so

Python代码:

#!/bin/python
#Filename:PythonCallCpp.py
from ctypes import *
import os
libPythonTest = cdll.LoadLibrary('./LibPythonTest.so')
print libPythonTest.Add(1,1)

运行:

python PythonCallCpp.py

运行结果:

2