python调用c/c++

一,封装若干函数到动态链接库:

1,mylib.h:

int addone(int a);

2,mylib.c(*这里文件后缀只能是.c):

/*mylib.c: 
>gcc -fpic -shared -o mylib.so \
    -I/usr/include/python2.7 \
    mylib.c wrap_mylib.c*/

int addone(int a) {
    return a+1;
}

3,wrap_mylib.c(*这里文件后缀只能是.c):

/* wrap_mylib.c: 
>gcc -fpic -shared -o mylib.so \
     -I/usr/include/python2.7 \
     mylib.c wrap_mylib.c*/

#include <Python.h>
#include "mylib.h"

PyObject* wrap_addone(PyObject* self, PyObject* args) 
{
  int n, result;

  if (! PyArg_ParseTuple(args, "i:fact", &n))
    return NULL;
  result = addone(n); /*这里调用C函数 */
  return Py_BuildValue("i", result);
}

static PyMethodDef mylibMethods[] = 
{
  {"addone", //Python环境下的函数名称
   wrap_addone,  //包裹函数
   METH_VARARGS,  //参数形式,将所有参数以元组方式打包
   "Add one to N"}, //说明
  {NULL, NULL,0,NULL}
};

void initmylib() 
{
  PyObject* m;
  m = Py_InitModule("mylib", mylibMethods);
}

4,编译成库(*库文件名只能是mylib.so):

>gcc -fpic -shared -o mylib.so \
     -I/usr/include/python2.7 \
     mylib.c wrap_mylib.c

5,使用:

bruce@bruce-Lenovo-IdeaPad-V450:~$ python
Python 2.7.12+ (default, Sep 17 2016, 12:08:02) 
[GCC 6.2.0 20160914] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import mylib
>>> mylib.addone(7)
8
>>>

二,封装"类"到动态链接库

其实并不是真正的c++类

1,noddy2.cpp:

/*>g++ -shared -fPIC -o noddy2.so noddy2.cpp -I/usr/include/python2.7 -L/usr/lib/x86_64-linux-gnu -lpython2.7*/
#include <Python.h>
#include "structmember.h"

typedef struct {
    PyObject_HEAD
    PyObject *first; /* first name */
    PyObject *last;  /* last name */
    int number;
} Noddy;

static void
Noddy_dealloc(Noddy* self)
{
    Py_XDECREF(self->first);
    Py_XDECREF(self->last);
    Py_TYPE(self)->tp_free((PyObject*)self);
}

static PyObject *
Noddy_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    Noddy *self;

    self = (Noddy *)type->tp_alloc(type, 0);
    if (self != NULL) {
        self->first = PyString_FromString("");
        if (self->first == NULL) {
            Py_DECREF(self);
            return NULL;
        }

        self->last = PyString_FromString("");
        if (self->last == NULL) {
            Py_DECREF(self);
            return NULL;
        }

        self->number = 0;
    }

    return (PyObject *)self;
}

static int
Noddy_init(Noddy *self, PyObject *args, PyObject *kwds)
{
    PyObject *first=NULL, *last=NULL, *tmp;

    static char *kwlist[] = {"first", "last", "number", NULL};

    if (! PyArg_ParseTupleAndKeywords(args, kwds, "|OOi", kwlist,
                                      &first, &last,
                                      &self->number))
        return -1;

    if (first) {
        tmp = self->first;
        Py_INCREF(first);
        self->first = first;
        Py_XDECREF(tmp);
    }

    if (last) {
        tmp = self->last;
        Py_INCREF(last);
        self->last = last;
        Py_XDECREF(tmp);
    }

    return 0;
}

static PyMemberDef Noddy_members[] = {
    {"first", T_OBJECT_EX, offsetof(Noddy, first), 0,
     "first name"},
    {"last", T_OBJECT_EX, offsetof(Noddy, last), 0,
     "last name"},
    {"number", T_INT, offsetof(Noddy, number), 0,
     "noddy number"},
    {NULL}  /* Sentinel */
};

static PyObject *
Noddy_name(Noddy* self)
{
    static PyObject *format = NULL;
    PyObject *args, *result;

    if (format == NULL) {
        format = PyString_FromString("%s %s");
        if (format == NULL)
            return NULL;
    }

    if (self->first == NULL) {
        PyErr_SetString(PyExc_AttributeError, "first");
        return NULL;
    }

    if (self->last == NULL) {
        PyErr_SetString(PyExc_AttributeError, "last");
        return NULL;
    }

    args = Py_BuildValue("OO", self->first, self->last);
    if (args == NULL)
        return NULL;

    result = PyString_Format(format, args);
    Py_DECREF(args);

    return result;
}

static PyMethodDef Noddy_methods[] = {
    {"name", (PyCFunction)Noddy_name, METH_NOARGS,
     "Return the name, combining the first and last name"
    },
    {NULL}  /* Sentinel */
};

static PyTypeObject NoddyType = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "noddy.Noddy",             /* tp_name */
    sizeof(Noddy),             /* tp_basicsize */
    0,                         /* tp_itemsize */
    (destructor)Noddy_dealloc, /* tp_dealloc */
    0,                         /* tp_print */
    0,                         /* tp_getattr */
    0,                         /* tp_setattr */
    0,                         /* tp_compare */
    0,                         /* tp_repr */
    0,                         /* tp_as_number */
    0,                         /* tp_as_sequence */
    0,                         /* tp_as_mapping */
    0,                         /* tp_hash */
    0,                         /* tp_call */
    0,                         /* tp_str */
    0,                         /* tp_getattro */
    0,                         /* tp_setattro */
    0,                         /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT |
        Py_TPFLAGS_BASETYPE,   /* tp_flags */
    "Noddy objects",           /* tp_doc */
    0,                         /* tp_traverse */
    0,                         /* tp_clear */
    0,                         /* tp_richcompare */
    0,                         /* tp_weaklistoffset */
    0,                         /* tp_iter */
    0,                         /* tp_iternext */
    Noddy_methods,             /* tp_methods */
    Noddy_members,             /* tp_members */
    0,                         /* tp_getset */
    0,                         /* tp_base */
    0,                         /* tp_dict */
    0,                         /* tp_descr_get */
    0,                         /* tp_descr_set */
    0,                         /* tp_dictoffset */
    (initproc)Noddy_init,      /* tp_init */
    0,                         /* tp_alloc */
    Noddy_new,                 /* tp_new */
};

static PyMethodDef module_methods[] = {
    {NULL}  /* Sentinel */
};

#ifndef PyMODINIT_FUNC	/* declarations for DLL import/export */
#define PyMODINIT_FUNC void
#endif
PyMODINIT_FUNC
initnoddy2(void)
{
    PyObject* m;

    if (PyType_Ready(&NoddyType) < 0)
        return;

    m = Py_InitModule3("noddy2", module_methods,
                       "Example module that creates an extension type.");

    if (m == NULL)
        return;

    Py_INCREF(&NoddyType);
    PyModule_AddObject(m, "Noddy", (PyObject *)&NoddyType);
}

2,使用:

bruce@bruce-Lenovo-IdeaPad-V450:~$ python
Python 2.7.12+ (default, Sep 17 2016, 12:08:02) 
[GCC 6.2.0 20160914] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import noddy2
>>> c=noddy2.Noddy("hello","world")  #创建类
>>> print c.first,c.last
hello world
>>>

https://blog.youkuaiyun.com/arnozhang12/article/details/5409155