用C語言得到Linux主機的IP地址

#include <stdio.h>;  #include <sys/types.h>;  #include <sys/socket.h>;  #include <sys/ioctl.h>;  #include <netinet/in.h>;  #include <net/if.h>;  #include <net/if_arp.h>;  #include <arpa/inet.h>;  #include <errno.h>;        #define ETH_NAME        "eth0"        int main()  {          int sock;          struct sockaddr_in sin;          struct ifreq ifr;                        sock = socket(AF_INET, SOCK_DGRAM, 0);          if (sock == -1)          {                  perror("socket");                  return -1;                          }                        strncpy(ifr.ifr_name, ETH_NAME, IFNAMSIZ);          ifr.ifr_name[IFNAMSIZ - 1] = 0;                        if (ioctl(sock, SIOCGIFADDR, &ifr) < 0)          {                  perror("ioctl");                  return -1;          }                memcpy(&sin, &ifr.ifr_addr, sizeof(sin));          fprintf(stdout, "eth0: %s\n", inet_ntoa(sin.sin_addr));                        return 0;  }