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;  
}