C extension not working in Python 3.7 says ImportError: dynamic module does not define module export function (PyInit_loop)

Question

I have created a C extension to create a loop and print 10 objects. It is compiling successfully but when I import it in python program and compile it then the terminal gives me an error saying:

ImportError: dynamic module does not define module export function (PyInit_loop)

Using ubuntu 19.04 with Python 3.7. I have created a virtualenv and I am doing whole work in it. Couldn't find specific solution anywhere but I someone said that the C file is hooking up with the Python2.7 in my system but since I am using virtualenv I don't expect this to be the case. Doing it for the first time.

This is my C Extension File

#include <Python.h>
#include <stdio.h>

static PyObject* loop(PyObject* self)
{
    int i =0;
    for(i=0;i<10;i++)
    {
        printf("The number is %d\n",i);
    }
    Py_RETURN_NONE;
}

static char loop_docs[] = "loop(): This function is going to create a printing loop for 10 times.\n";

static PyMethodDef loop_methods[] = {
    {"loop", (PyCFunction)loop, METH_NOARGS, loop_docs},
    {NULL}
};

static struct PyModuleDef loop_module_def = 
{
    PyModuleDef_HEAD_INIT,
    "loop",
    "Module that is still in development",
    -1,
    loop_methods
};

PyMODINIT_FUNC PyInit_fibonacci(void){
    Py_Initialize();

    return PyModule_Create(&loop_module_def);
}

this is my setup.py

from distutils.core import setup, Extension
setup(name='loop', version='1.0',ext_modules=[Extension('loop', ['loop.c'])])

this is the file I am trying to run

import loop #<- Here Error Occurs

print(loop.loop())

Answer 1

The entry point of your native module (function with PyMODINIT_FUNC) should have a name based on the module name.
Here, this function is named PyInit_fibonacci() but your module is named loop.
I would suggest to name your function PyInit_loop() (or alternatively name your module fibonacci).

(https://docs.python.org/3/extending/building.html#c.PyInit_modulename)

Note that the error message shows the expected name for the missing function:

ImportError: dynamic module does not define module export function (PyInit_loop)