#include <iostream>

#include <unistd.h>  // get/set hostname
#include <limits.h>  // HOST_NAME_MAX

#include <stdio.h>   // perror
#include <errno.h>   // errno
#include <string.h>  // strerror


using namespace std;

const int LEN = HOST_NAME_MAX;

int main() {
     char name[LEN];
     char eName[1];

     if (0 != gethostname(eName, 1)) {
         perror("Failed to get the host name");
     }

     if (0 != sethostname(eName, 1)) {
         perror("Failed to set the host name");
     }

     return 0;
}