Interactive stuffs

cpp.cc

#include <bits/stdc++.h>

using namespace std;

void read(int& x, int& y) {
	cin >> x >> y;
	cerr << "cc< " << x << " " << y << endl;
}

void write(int x, int y) {
	cout << x << " " << y << endl;
	cerr << "cc> " << x << " " << y << endl;
}

int main(int argc, char** argv) {
	int x = 2, y = 4;
	while(x < 10) {
		write(x, y);
		read(x, y);
		++x;
	}

	return 0;
}

py.py

#!/usr/bin/python3

import sys

def read():
	x, y = map(int, input().split())
	sys.stderr.write("py< {} {}\n".format(x, y))
	sys.stderr.flush()
	return [ x, y ]

def write(x, y):
	print("{} {}".format(x, y))
	sys.stdout.flush()
	sys.stderr.write("py> {} {}\n".format(x, y))
	sys.stderr.flush()

while True:
	x, y = read()
	y += 1
	write(x, y)

run.sh

g++ -o cpp cpp.cc
mkfifo fifo
# ./cpp <fifo | tee >(./py.py | tee fifo)
./cpp <fifo | ./py.py >fifo
rm fifo	cpp