Help with ctypes and "c_int*"

[Jstechg]

I am python beginner and I am trying to run a simple python program that call a c function using ctypes
on a linux Ubuntu PC.

It is based on web examples, but I have not the full source code of "test_funtionslib_using_wrapper.py".

Besides I prefer not to use additional python packets, as numpy or others, and being able to run it on initial python installation for Ubuntu.

funtionslib.c

#include <stdio.h>

void c_square(int n, double *array_in, double *array_out)
{
  int i;

  for (i=0; i<n; i++)
  {
    array_out[i] = array_in[i] * array_in[i];
  }
}

testlibwrapper.py

from ctypes import *
import sys

clib_path = "./functionslib_linux.so"
try:
  c_functions_lib = CDLL(clib_path)
except:
  print("No se ha podido abrir la libreria " + str(clib_path))

def do_square_using_c(list_in):
  n = len(list_in)
  c_array_in = (c_double* n)(*list_in)
  c_array_out = (c_double* n)()

  function_c_square = c_functions_lib.c_square
  function_c_square.restype = None
  function_c_square(c_int(n), c_array_in, c_array_out)

  return c_array_out[:]

test_funtionslib_using_wrapper.py

from testlibwrapper import do_square_using_c

my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
squared_list = do_square_using_c(*my_list)

compile.sh (optional script to compile C linux library)

gcc -shared -Wl,-soname,testlib -o functionslib_linux.so -fPIC functionslib.c

run_python.sh (optional script to run python)

  #!/bin/bash
  python testlibwrapper.py

When I run, I get the error:

Traceback (most recent call last):
File "test_funcionslib_using_wrapper.py", line 7, in <module>
squared_list = do_square_using_c(*my_list)
TypeError: do_square_using_c() takes exactly 1 argument (10 given)


How can I fix this error without using numpy?

The original source of "test_funtionslib_using_wrapper.py" on the web is:

from testlibwrapper import do_square_using_c
import numpy as np

#Previous declarations or initializations are not detailed on the web
# (. . .)

my_list = np.arange(1000)
squared_list = do_square_using_c(*my_list)

[Larz60+]

try removing the * from squared_list = do_square_using_c(*my_list)