watch directory for changes and print "update" on change

watch.c

#include <sys/event.h>
#include <sys/time.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <iostream>

int main (int argc, const char *argv[])
{
    // argv[1]
    
    int f, kq, nev;
    struct kevent change;
    struct kevent event;
    
    kq = kqueue();
    // if (kq == -1)
        // perror("kqueue");
    
    f = open("/Users/max/directory", O_RDONLY); // it wont watch subdirs
    // if (f == -1)
        // perror("open");
    
    EV_SET(&change, f, EVFILT_VNODE,
           EV_ADD | EV_ENABLE | EV_ONESHOT,
           NOTE_DELETE | NOTE_EXTEND | NOTE_WRITE | NOTE_ATTRIB,
           0, 0);
    
    for (;;) {
        nev = kevent(kq, &change, 1, &event, 1, NULL);
        if (nev == -1) {
            // perror("kevent");
        }
        else if (nev > 0) {
            if (event.fflags & NOTE_DELETE) {
                std::cout << "update\n"; // File deleted
                break;
            }
            if (event.fflags & NOTE_EXTEND ||
                event.fflags & NOTE_WRITE)
                std::cout << "update\n"; // File modified
                
            if (event.fflags & NOTE_ATTRIB)
                std::cout << "update\n"; // File attributes modified
                
        }
    }
    
    close(kq);
    close(f);
    return EXIT_SUCCESS;
}

there is an issue with stdout and stderr.