Unable to make executable that properly communicates with node.js

I'm testing the communication between node.js and executables launched as child processes. An executable will be launched from within node.js via child_process.spawn() and its output will be monitored by node.js. I'm testing this capability both on Linux and Windows OSs.

I've successfully spawned tail -f /var/log/syslog and listened to its output, but my own executables can't seem to write correctly to stdout (in whatever form it exists when captured by node.js).

Test code:

#include <iostream>
#include <stdio.h>
#include <unistd.h>

int main()
{
    using namespace std;

    long x = 1;

    while (true)
    {

        fprintf(stdout, "xtime - %ld\n", x++);
        usleep(1000000);
    }
}

(Note: some includes may be useless; I've not checked them)