Linux下C/C++怎样通过主机名获得IP?

#include <stdio.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <netdb.h>



int main(int argc, char **argv)

{

        struct hostent *ip;

        unsigned long hostname;



        if (argc != 2)

        {

                printf("Need to specify an IP address.\n");

                return -1;

        }

        if ((hostname = inet_addr(argv[1])) == -1)

        {

                printf("Could not find %s\n", argv[1]);

                return -1;

        }

        else

        {

                printf("hostname : %ld\n", hostname);

        }

        if ((ip = gethostbyaddr((char *)&hostname, sizeof(long), AF_INET)) != NULL)

                printf("%s is %s\n", argv[1], ip->h_name);

        else

                printf("Could not resolve %s\n", argv[1]);

        return 0;

}