#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
using namespace std;

int main(int argc, char **argv)
{
  int fds[2];
  pid_t pid;

  if (pipe(fds) == -1) {    // create pipe
    perror("pipe failed"); exit(1);
  }
  if ((pid = fork()) < 0) { // spawn child
    perror("fork failed"); exit(2);
  }

  if (pid == 0) {       // child

    close(fds[1]);      // close output
    char c;
    while (read(fds[0], &c, 1) > 0) {
      cout << "read: " << c << endl;
    }
    close(fds[0]);   // close input
    cout << "child done" << endl;

  } else {          // parent 

    close(fds[0]);  // close input

    char msg[] = "hello..world..";
    write(fds[1], msg, strlen(msg));
    close(fds[1]);  // close output -> EOF

    waitpid(pid, 0, 0);  // wait for child
    cout << "parent done" << endl;    
  }
  exit(0);
}