获取某张网卡的IP地址

#include <string.h>

#include <sys/socket.h>

#include <net/if.h>

#include <sys/ioctl.h>

#include <netinet/in.h>

#include <stdio.h>
#define IP_ADDR_LEN     20

//   intf:指向网卡名的指针

//   ipaddr:指向IP地址的指针

int get_ipaddr(char *intf,char *ipaddr) 

{

            int  sock;
            struct ifreq ifr;

            struct sockaddr_in *sin = NULL;
            memset(&ifr,0,sizeof(struct ifreq));
            sock = socket(AF_INET, SOCK_DGRAM, 0); 
            strcpy(ifr.ifr_name, intf);
            if (ioctl(sock, SIOCGIFADDR, &ifr) < 0)
                printf("ioctl error\n");
            sin = (struct sockaddr_in*) &ifr.ifr_addr;
            inet_ntop(AF_INET, &sin->sin_addr.s_addr, ipaddr, IP_ADDR_LEN);

            return 0;

}

/*          test the function         */

void main()

{

             char   *name="eth0";

             char   ip[IP_ADDR_LEN];

             get_ipaddr(name,ip);

             printf("IP:%s\n",ip);

}