/* lookup.c: *  * Example of gethostbyname(3) : */#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <string.h>#include <errno.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <netdb.h>extern int h_errno;intmain(int argc,char **argv) {    int x, x2;    struct hostent *hp;    for ( x=1; x<argc; ++x ) {        /*         * Look up the host name :         */        hp = gethostbyname(argv[x]);        if ( !hp ) {            /* Report lookup failure */            fprintf(stderr,                "%s: host '%s'\n",                hstrerror(h_errno),                argv[x]);            continue;        }        /*         * Report the findings :         */        printf("Host %s :\n",argv[x]);        printf("  Officially:\t%s\n",            hp->h_name);        fputs("  Aliases:\t",stdout);        for ( x2=0; hp->h_aliases[x2]; ++x2 ) {            if ( x2 )                fputs(", ",stdout);            fputs(hp->h_aliases[x2],stdout);        }        fputc('\n',stdout);        printf("  Type:\t\t%s\n",            hp->h_addrtype == AF_INET                ? "AF_INET"                : "AF_INET6");        if ( hp->h_addrtype == AF_INET ) {            for ( x2=0; hp->h_addr_list[x2]; ++x2 )                printf("  Address:\t%s\n",                    inet_ntoa( *(struct in_addr *)                        hp->h_addr_list[x2]));        }        putchar('\n');    }    return 0;}