Communicating continuously between python script and C app

c, python

Solution

There are several possible ways.

You could start the C program from the python program using the `subprocess` module. In that case you could write from the python program to the standard input of the C program. This is probably the easiest way.

import subprocess

network_data = 'data from the network goes here'
p = subprocess.Popen(['the_C_program', 'optional', 'arguments'], 
                     stdin=subprocess.PIPE)
p.stdin.write(network_data)

N.B. if you want to send data multiple times, then you should not use `Popen.communicate()`.

Alternatively, you could use socket. But you would have to modifiy both programs to be able to do that.

Edit: J.F Sebatian's comment about using a pipe on the command line is very true, I forgot about that! But the abovementioned technique is still useful, because it is one less command to remember and especially if you want to have two-way communication between the python and C programs (in which case you have to add `stdout=subprocess.PIPE` to the `subprocess.Popen` invocation and then your python program can read from `p.stdout`).

Problem

I have a python script that interfaces with some network pool to read data from, that is continuously 320 bits. This 320 bits should be forward to some C app, that continuously reads these 320 bits from the python script and places them into an int array[8]. To be honest, I have no idea whether this is possible at all and would be thankful for a starting point for this issue. I tried to incooperate some of your ideas, trying to send data via stdin from python to the C app: test.exe: ``` #include <stdio.h> int main(void) { int ch; /* read character by character from stdin */ do { ch = fgetc(stdin); putchar(ch); } while (ch != EOF); return 0; } ``` test.py: ``` def run(self): while True: payload = 'some data' sys.stdout.write(payload) time.sleep(5) ``` Then I start this whole thing using a pipe: python test.py | test.exe Unfortunately, there is no data that is received on the test.exe side, shouldn't this data ba available on stdin?

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