linux获取IP地址

 #include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
int sock_fd;
struct  my_addr;
struct ifreq ifr;
    unsigned char * addr;
#define ETH_INTERFACE_NAME    "eth0"
    /**//* Get socket file descriptor */
    if ((sock_fd = socket(PF_INET, SOCK_DGRAM, 0)) == -1)...{
        perror("socket");
        exit(1);
    }
    /**//* Get IP Address */
    strncpy(ifr.ifr_name, ETH_INTERFACE_NAME, IF_NAMESIZE);
    ifr.ifr_name[IFNAMSIZ-1]='\0';
    if (ioctl(sock_fd, SIOCGIFADDR, &ifr) < 0)...{
        perror("ioctl");
        exit(1);
    }
    memcpy(&my_addr, &ifr.ifr_addr, sizeof(my_addr));
    addr=inet_ntoa(my_addr.sin_addr);