(.env) [boris@fedora33server FIBONACHI]$ cat test.c
#include <Python.h>
int Cfib(int n)
{
if (n < 2)
return n;
else
return Cfib(n-1)+Cfib(n-2);
}
// Our Python binding to our C function
// This will take one and only one non-keyword argument
static PyObject *fib(PyObject* self, PyObject* args)
{
// instantiate our `n` value
int n;
// if our `n` value
if(!PyArg_ParseTuple(args, "i", &n))
return NULL;
// return our computed fib number
int result = Cfib(n);
return Py_BuildValue("i",result);
}
// Our Module's Function Definition struct
// We require this `NULL` to signal the end of our method
// definition
static PyMethodDef myMethods[] = {
{ "fib", fib, METH_VARARGS, "Calculate fibonacii value" },
{ NULL, NULL, 0, NULL }
};
// Our Module Definition struct
static struct PyModuleDef myModule = {
PyModuleDef_HEAD_INIT,
"myModule",
"Test Module",
-1,
myMethods
};
// Initializes our module using our above struct
PyMODINIT_FUNC PyInit_myModule(void)
{
return PyModule_Create(&myModule);
}
(.env) [boris@fedora33server FIBONACHI]$ cat setup.py
from distutils.core import setup, Extension
setup(name = 'myModule', version = '1.0', \
ext_modules = [Extension('myModule', ['test.c'])])
(.env) [boris@fedora33server FIBONACHI]$ python3 setup.py install
(.env) [boris@fedora33server FIBONACHI]$ cat MyProg.py
import myModule
a = int(input("Input number:"))
print(myModule.fib(a))
(.env) [boris@fedora33server FIBONACHI]$ python MyProg.py
Input number:11
89
Relatively complicated sample based on
and minor refactoring just to make things clear
(.env) [boris@sever33fedora enhancePython]$ cat demo.h
unsigned long cfactorial_sum(char num_chars[]);
unsigned long ifactorial_sum(long nums[], int size);
unsigned long factorial(long n);
(.env) [boris@sever33fedora enhancePython]$ cat demolib.c
#include <stdio.h>
#include "demo.h"
unsigned long cfactorial_sum(char num_chars[]) {
unsigned long fact_num;
unsigned long sum = 0;
for (int i = 0; num_chars[i]; i++) {
int ith_num = num_chars[i] - '0';
fact_num = factorial(ith_num);
sum = sum + fact_num;
}
return sum;
}
unsigned long ifactorial_sum(long nums[], int size) {
unsigned long fact_num;
unsigned long sum = 0;
for (int i = 0; i < size; i++) {
fact_num = factorial(nums[i]);
sum += fact_num;
}
return sum;
}
unsigned long factorial(long n) {
if (n == 0)
return 1;
return (unsigned)n * factorial(n-1);
}
(.env) [boris@sever33fedora enhancePython]$ cat demo.c
#include <Python.h>
#include <stdio.h>
#include "demo.h"
// wrapper function for cfactorial_sum
static PyObject *DemoLib_cFactorialSum(PyObject *self, PyObject *args) {
char *char_nums;
if (!PyArg_ParseTuple(args, "s", &char_nums)) {
return NULL;
}
unsigned long fact_sum;
fact_sum = cfactorial_sum(char_nums);
return Py_BuildValue("i", fact_sum);
}
// wrapper function for ifactorial_sum
static PyObject *DemoLib_iFactorialSum(PyObject *self, PyObject *args) {
PyObject *lst;
if (!PyArg_ParseTuple(args, "O", &lst)) {
return NULL;
}
int n = PyObject_Length(lst);
if (n < 0) {
return NULL;
}
long nums[n];
for (int i = 0; i < n; i++) {
PyLongObject *item = PyList_GetItem(lst, i);
/* long num = PyLong_AsLong(item); */
nums[i] = PyLong_AsLong(item);
}
unsigned long fact_sum;
fact_sum = ifactorial_sum(nums, n);
return Py_BuildValue("i", fact_sum);
}
// module's function table
static PyMethodDef DemoLib_FunctionsTable[] = {
{
"sfactorial_sum", // name exposed to Python
DemoLib_cFactorialSum, // C wrapper function
METH_VARARGS, // received variable args (but really just 1)
"Calculates factorial sum from digits in string of numbers" // documentation
}, {
"ifactorial_sum", // name exposed to Python
DemoLib_iFactorialSum, // C wrapper function
METH_VARARGS, // received variable args (but really just 1)
"Calculates factorial sum from list of ints" // documentation
}, {
NULL, NULL, 0, NULL
}
};
// modules definition
static struct PyModuleDef DemoLib_Module = {
PyModuleDef_HEAD_INIT,
"demo", // name of module exposed to Python
"Demo Python wrapper for custom C extension library.", // module documentation
-1,
DemoLib_FunctionsTable
};
PyMODINIT_FUNC PyInit_demo(void) {
return PyModule_Create(&DemoLib_Module);
}
(.env) [boris@sever33fedora enhancePython]$ cat setup.py
from setuptools import Extension, setup
module = Extension("demo",
sources=[
'demo.c',
'demolib.c'
])
setup(name='demo',
version='1.0',
description='Python wrapper for custom C extension',
ext_modules=[module])
(.env) [boris@sever33fedora enhancePython]$ python setup.py install
(.env) [boris@sever33fedora enhancePython]$ python MyProg.py
Callng sfactorial_sum("1234567") gives
5913
Calling ifactorial_sum([1,2,3,4,5,6,7]) gives
5913
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