Python call functions written in C

Calling functions written purely with C using python code.

Python is one of the best languages to write code if you want to develop something quickly.

From what i can see (get it? see –> C), i would only use this in cases where with python you are not able to access some system resource or C gives you the performance boost that you require.

The following is the C code that i will use for this example.

// filename : c_tools.c
// author   : eshan shafeeq
// date     : 2017-10-06

int addAll( int value );
int addAll( int value ){
    int total=0;
    while( value > 0 ){
        total+=value;
        value--;
    }
    return total;
}

I compiled the above the code into c-tools.so using the following command.

gcc -shared -fPIC c_tools.c -o c-tools.so

The code above just keeps adding value to total while value gets deducted and value is still greater than 0. Nothing too complicated, since this is just for demonstration. Here is the python code which calls the addAll function.

# filename  : python-call-c-functions.py
# author    : eshan shafeeq
# description : Use python to call function written using c

from ctypes import *

# Loading the shared object file
tools = CDLL('./c-tools.so')

value = 6
total = tools.addAll( value )
print('Sum of the values added up : ' + str(total) )

The code above is also pretty straight forward. We can see how it’s able to load the shared C object file, and call the function within the object file as well. Doing so while passing in a value which is defined in python. This gives us very interesting possibilities in the future. I am so going to use this method to control GPIO pins on the raspberry pi just because i can!

Below is the output generated from the program.

python python-call-c-functions.py
Sum of the values added up : 21