C Programming

How to Call a C function in Python

Python and C are popular programming languages allowing users to build several mobile and web-based applications. However, these programming languages require different environments and packages to run on your system. But they can be integrated, especially calling a C function in Python.

If you are unsure whether it can be possible to call a C function in Python, follow this article’s guidelines for further help.

Call a C Function in Python

Calling a C function in Python is a matter of simple steps discussed below:

Step 1: First, create a C file on any system. I am creating the file on a Linux system using the following command:

nano mycode.c

Step 2: Inside the file, add the following function.

int mycode(int numb)


    if (numb == 0)


        // Do not perform any operation if number is 0.

        return 0;


        // Return 1 else return 0 if number is power of 2

        return ((numb & (numb - 1)) == 0 ? 1 : 0) ;



Note: You can add any C function you want inside the file.

Step 3: Now, you must generate a shared library “libfun.so” of the file using the following command:

cc -fPIC -shared -o libfun.so mycode.c

This generates the “libfun.so” shared library on the system.

ctypes is a Python library that allows users to call a C function inside a Python program. To use this library, the users must import it at the start of the Python program.

Step 4: Let’s create a Python file using nano editor in Linux from the following command:

nano myfile.py

Step 5: Inside the file, add the following code:

import ctypes

Num= 16

# libfun loads the python file

# via fun.mycode(),

# Access the C function

fun = ctypes.CDLL("location of libfun.so") # Or full path to file

# ctypes will check it whenever an argument is passed


fun.mycode.argtypes = [ctypes.c_int]


# Call the function using instant (fun)

# return the value by function in C

# code

returnVale = fun.mycode(Num)

Note: Ensure replacing “mycode()” with your function name and the location of libfun.so file.

Step 6: Save the file using “CTRL+X”, add “Y” and enter to exit.

Step 7: Execute the Python code to confirm its successful compilation on the system.

python3 myfile.py

In this way, you can call a C function in Python on any system by following the above-given steps.


Calling a C function inside the Python program can be done easily by first creating a C function inside a file with a .c extension. Then compile the file to generate a shared library after that, import “ctypes” library in a Python program and use the shared library inside the code to call a function in Python on any system.

About the author

Awais Khan

I'm an Engineer and an academic researcher by profession. My interest for Raspberry Pi, embedded systems and blogging has brought me here to share my knowledge with others.