c调用python记录

  C调用python的实例。

  1. 应用场景

    c代码中需要数据库的支持，但是引入数据库十分的复杂且麻烦，所以考虑用python读取配置文件，然后将数据返回到C。

  2.调用步骤

    a, 添加必要的宏和python路径

#define MS_NO_COREDLL

#include "C:\Python27\include\python.h"

#pragma comment(lib, "C:\\Python27\\libs\\python27.lib")

    b,初始化python解释器

    Py_Initialize();
    if ( !Py_IsInitialized() )
    {
        printf( "Cannot initialize python27.\n" );
        return -1;
    }

    c,将python文件的字符串转换为python字符，并导入python文件。

    /*Create python string symbol, s stand for string and pytest stand for pytest.py*/
    pName = Py_BuildValue( "s", "pytest" );

    /*Import the python file.*/
    pModule = PyImport_Import( pName );
    if ( !pModule )
    {
        printf("Couldnot find pytest.py .\n");
        return -1;
    }

    d,导入python文件中的处理函数

    pDict = PyModule_GetDict( pModule );
    if ( !pDict )
    {
        return -1;
    }

    pFunc = PyDict_GetItemString( pDict, functionName );
    if ( !PyCallable_Check( pFunc ) )
    {
        printf("Couldnot find function.\n" );
        return -1;
    }

    e,传入参数，入参类型为tuple.PyTuple_New( 1 )产生一个tuple,有1个元素。Py_BuildValue( "i", 1 )将数字1转换为python的整形类型。PyObject_CallObject()调用执行函数执行。

    pArgs = PyTuple_New( 1 );
    PyTuple_SetItem( pArgs, 0, Py_BuildValue( "i", 1 ) );

    pRetVal = PyObject_CallObject( pFunc, pArgs );

    f,Py_DECREF清除并释放资源。

    g,Py_Finalize()释放python状态机。

  完整的代码如下，需要在同目录下创建test.txt文件，保证数据的存在。

textCPython.c

#include <stdio.h>
#include <stdlib.h>

#define MS_NO_COREDLL

#include "C:\Python27\include\python.h"

#pragma comment(lib, "C:\\Python27\\libs\\python27.lib")

int ReadFile()
{
    PyObject* pName;
    PyObject* pModule = NULL;
    PyObject* pDict = NULL;
    PyObject* pFunc = NULL;
    PyObject* pArgs = NULL;
    PyObject* pRetVal = NULL;
    PyObject* pList = NULL;

    int i = 0;
    Py_ssize_t num = 0;

    char* functionName = "GetFileContent";

    Py_Initialize();
    if ( !Py_IsInitialized() )
    {
        printf( "Cannot initialize python27.\n" );
        return -1;
    }

    /*Create python string symbol, s stand for string and pytest stand for pytest.py*/
    pName = Py_BuildValue( "s", "pytest" );

    /*Import the python file.*/
    pModule = PyImport_Import( pName );
    if ( !pModule )
    {
        printf("Couldnot find pytest.py .\n");
        return -1;
    }

    pDict = PyModule_GetDict( pModule );
    if ( !pDict )
    {
        return -1;
    }

    pFunc = PyDict_GetItemString( pDict, functionName );
    if ( !PyCallable_Check( pFunc ) )
    {
        printf("Couldnot find function.\n" );
        return -1;
    }

    pArgs = PyTuple_New( 1 );
    PyTuple_SetItem( pArgs, 0, Py_BuildValue( "i", 1 ) );

    pRetVal = PyObject_CallObject( pFunc, pArgs );

    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "tupleno" ) ) );   
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "ringprofile" ) ) );   
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "id" ) ) );   
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "time" ) ) );   
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "on1" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "off1" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "on2" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "off2" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "on3" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "off3" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "on4" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "off4" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "on5" ) ) );
    printf("%s\n", PyString_AsString( PyDict_GetItemString( pRetVal, "off5" ) ) );


    Py_DECREF( pName );
    Py_DECREF( pDict );
    Py_DECREF( pArgs );
    Py_DECREF( pModule );

    Py_Finalize();
    return 1;

}

int main()
{
    if ( -1 == ReadFile() )
    {
        return -1;
    }
    return 0;
}

pytest.py

import os


def GetListFromLine( str ):
    itemList = [ li.replace( ' ', '' ) for li in str.split( ':' ) ]
    return [ li.replace( '\n', '' ) for li in itemList ]

def GetFileContent( id ):
    f = open( 'test.txt' )
    try:
        retVal = []

        for line in f.readlines():
            if line != '\n':
                retVal.append( GetListFromLine( line ) )
        return dict( retVal )

    finally:
        f.close()

test.txt

tupleno: 1
ringprofile : 1
id : 0
time : 12000
on1 : 100
off1 : 400
on2 : 0
off2 : 0
on3 : 0
off3 : 0
on4: 0
off4 : 0
on5 : 0
off5 : 0