Linux下C語言實現「域名「轉「ip「

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

int main(int argc, char *argv[])
{
        assert(argc == 2);
        const char *hostname = argv[1];
        struct hostent* host;

        host = gethostbyname(hostname);
        if (host == NULL)
        {
                perror("cannot get host by hostname");
                exit(EXIT_FAILURE);
        }

        const char *hostip = inet_ntoa(*((struct in_addr*)host->h_addr));
        printf("host ip = %s \n", hostip);
        return EXIT_SUCCESS;
}