python与c语言交互---学习012

1.C语言是结构化编程语言，Python是面向对象的语言，Python调用C语言，没有问题。但是，反过来则不行，不许C调用Python。

使用Python/C API中的PyImport_Import()函数可以在C程序中导入Python模块。

分析：先引用模块（PyImport_ImportModule），

然后获取模块中的函数（PyObject_GetAttrString），

对c传入python 的参数做类型转换（Py_BuildValue("(s)","hello_python")），

最后直接调用函数并传递参数（PyEval_CallObject）。

#include "/usr/include/python2.5/Python.h"

#include <stdio.h>

int main(int arg,char **argv){
PyObject *modelname,*model,*dict,*func,*args;
char *name="os";//模块名

//初始化Python
Py_Initialize();
if (!Py_IsInitialized()){
printf("初始化失败\n");
return -1;
}

//直接运行Python语句
PyRun_SimpleString("print '初始化成功'");

//导入Python模块
modelname=PyString_FromString(name);
model=PyImport_Import(modelname);

if (model){
printf("Load model ok\n");
}
else{
printf("Model %s not found!\n",name);
return -1;
}

dict=PyModule_GetDict(model);

if(!dict){
printf("获取字典失败\n");
return -1;
}
else{
printf("获取字典成功\n");
}

//从模块中找到“System”函数
func=PyDict_GetItemString(dict,"system");

if(!func || !PyCallable_Check(func)){
printf("函数无效\n");
return -1;
}

args=PyTuple_New(1);

PyTuple_SetItem(args,0,Py_BuildValue("s","ls"));//l＝long，s＝string...

//调用函数
PyObject_CallObject(func,args);

Py_DECREF(modelname);
Py_DECREF(model);
Py_DECREF(func);
Py_DECREF(args);
Py_DECREF(dict);
//垃圾回收
Py_Finalize();
return 0;
}

------------------------------------------------------------------------我是分割线-------------------------------------------------------

call.py

def test():

    print 'hello world'

def add(a,b):

    return a + b

api.py

import io

def load_test():
fp = open('call.py','r')
buffer = ''
if fp:
buffer = fp.read()
fp.close()
return buffer

cpp代码:

#include <stdio.h>

#include <stdlib.h>

#include <Python.h>

int main(int argc, char *argv[])

{

    Py_Initialize();  

    if(!Py_IsInitialized())   

    {  

        return -1;  

    }  

    

    PyRun_SimpleString("import sys");

    PyRun_SimpleString("sys.path.append('./')");

    PyObject* pName;

    PyObject* pModule;

    PyObject* pDict;

    PyObject* pFunc;

    

    pName = PyString_FromString("api");

    pModule = PyImport_Import(pName);

    if(!pModule)

    {

        printf("can't find call.py");

        getchar();

        return -1;

    }

    

    pDict = PyModule_GetDict(pModule);

    if(!pDict)

    {

        return -1;

    }

    

    {

        pFunc = PyDict_GetItemString(pDict,"load_test");

        if(!pFunc || !PyCallable_Check(pFunc))

        {

            printf("can't find function [test]");

            getchar();

            return -1;

        }

        

        PyObject *pFn = PyObject_CallObject(pFunc,0);

        char* buffer = PyString_AsString(pFn);

        printf("%s\n",buffer);

        

        PyObject* o = Py_CompileString(buffer,"none",Py_file_input);

        PyObject* m = PyImport_ExecCodeModule("a.a",o);

        PyObject* d = PyModule_GetDict(m);

        pFunc = PyDict_GetItemString(d,"add");

        if(!pFunc || !PyCallable_Check(pFunc))

        {

            printf("can't find function [add]");

            getchar();

            return -1;

        }

        

        PyObject* args = PyTuple_New(2);

        PyTuple_SetItem(args,0,Py_BuildValue("l",3));

        PyTuple_SetItem(args,1,Py_BuildValue("l",4));

        PyObject *pAdded = PyObject_CallObject(pFunc,args);

        int ret = PyInt_AsLong(pAdded);  

        printf("add value:%d\n",ret);    

    }

 

    Py_Finalize();    

    system("PAUSE");    

    return 0;

}

这段代码和上一篇有点区别

主要区别是从从内存载入python模块然后调用函数

主要部分是这块:

PyObject* o = Py_CompileString(buffer,"none",Py_file_input);
PyObject* m = PyImport_ExecCodeModule("a.a",o);
PyObject* d = PyModule_GetDict(m);

buffer是python源码字符串

在python2.7中执行正常

编译：

gcc -o ./python_c_function ./python_c_function.c  -I/usr/include/python2.6   -L/usr/lib/python2.6 -lpython

[root@localhost c_python]# ./python_c_function
def test():
print 'hello world'

def add(a,b):
return a + b

add value:7