IPV6 Host Name Resolving in Linux

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

int main(int argc, char *argv[])
{

                char tmphstbuf [4096];
                size_t hstbuflen  = sizeof (tmphstbuf);
                struct hostent hostinfo_buf = {0,};
                struct hostent *hostresult = NULL;
                int herr ;

                int ret = -1 ;

                size_t len;

                char ip_addr[INET6_ADDRSTRLEN] = {0,};
                 struct sockaddr_in6 addr;

                len = sizeof(tmphstbuf);

                ret = gethostbyname_r(argv[1], &hostinfo_buf, tmphstbuf, len, &hostresult, &herr);


                printf("Addresses:\t");
                inet_ntop(AF_INET6, hostinfo_buf.h_addr_list[0], ip_addr, INET6_ADDRSTRLEN);
                 printf("%s\n", ip_addr);


}

/* Keep add your hostnames in /etc/hosts file */