gethostbyname_test.cpp

//
// Created by jxq on 19-8-6.
//

#include <iostream>
#include <stdio.h>
#include <cstring>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#define ERR_EXIT(m) \
        do \
        { \
            perror(m); \
            exit(EXIT_FAILURE); \
        } while (0);

int getlocalip(char *ip)
{
    char host[100] = {0};
    if (gethostname(host, sizeof host) < 0)
    {
        ERR_EXIT("gethostname");
    }

    struct hostent *hp;
    if ((hp = gethostbyname(host)) == NULL)
    {
        ERR_EXIT("gethostbyname");
    }
    strcpy(ip, inet_ntoa(*(struct in_addr*)hp->h_addr_list[0]));
    return 0;
}

int main(void)
{
//    char host[100] = {0};
//    if (gethostname(host, sizeof host) < 0)
//    {
//        ERR_EXIT("gethostname");
//    }
//
//    struct hostent *hp;
//    if ((hp = gethostbyname(host)) == NULL)
//    {
//        ERR_EXIT("gethostbyname");
//    }
//    int i = 0;
//    while (hp->h_addr_list[i] != NULL)
//    {
//        printf("%s\n", inet_ntoa(*(struct in_addr*)hp->h_addr_list[i]));
//        ++i;
//    }

    char ip[16] = {0};
    getlocalip(ip);
    printf("localip = %s\n", ip);

    return 0;
}