prg7_1.c

Unix下用C语言进行网络编程的范例

// File: prg7_1.c
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

main(int argc, const char **argv)
{
    ulong_t addr;
    struct hostent *hp;
    char **p;
    if (argc != 2) {
        (void) printf("usage: %s host_name\n", argv[0]);
        exit (1);
        }
    hp = gethostbyname(argv[1]);
    if (hp == NULL) {
        (void) printf("host information for %s not found\n", argv[1]);
        exit (2);
        }
    for (p = hp->h_addr_list; *p != 0; p++) {
        struct in_addr in;
        char **q;
        (void) memcpy(&in.s_addr, *p, sizeof (in.s_addr));
        (void) printf("%s\t%s", inet_ntoa(in), hp->h_name);
        for (q = hp->h_aliases; *q != 0; q++)
            (void) printf(" %s", *q);
        (void) putchar('\n');
        }
    exit (0);
}