Linux C 获取本机IP

#include <stdio.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <net/if.h>
#include <arpa/inet.h>
#define ERRORIP "cannot find host ip"
char *ip_search(void)
{
    int sfd, intr;
    struct ifreq buf[16];
    struct ifconf ifc;
    sfd = socket (AF_INET, SOCK_DGRAM, 0); 
    if (sfd < 0)
        return ERRORIP;
    ifc.ifc_len = sizeof(buf);
    ifc.ifc_buf = (caddr_t)buf;
    if (ioctl(sfd, SIOCGIFCONF, (char *)&ifc))
        return ERRORIP;
    intr = ifc.ifc_len / sizeof(struct ifreq);
    while (intr-- > 0 && ioctl(sfd, SIOCGIFADDR, (char *)&buf[intr]));
    close(sfd);
    return inet_ntoa(((struct sockaddr_in*)(&buf[intr].ifr_addr))-> sin_addr);
}
int main(void)
{
    printf("%s\n", ip_search());
    return 0;
}

 转，完全不懂啊，( > c < ) !