Linux C代码 获取IP地址

Ubuntu 16.04下，可编译通过：

 #include <stdio.h>
 #include <ifaddrs.h>
 #include <arpa/inet.h>
 #include <cstring>

 #define MAX_LENGTH 254

 int main(void)
 {
     char ipAddr[MAX_LENGTH];

     ipAddr[] = '\0';

     struct ifaddrs * ifAddrStruct = NULL;
     void * tmpAddrPtr = NULL;

     if (getifaddrs(&ifAddrStruct) != )
     {
         //if wrong, go out!
         printf("Somting is Wrong!\n");
         return -;
     }

     struct ifaddrs * iter = ifAddrStruct;

     while (iter != NULL) {
         if (iter->ifa_addr->sa_family == AF_INET) { //if ip4
             // is a valid IP4 Address
             tmpAddrPtr = &((struct sockaddr_in *)iter->ifa_addr)->sin_addr;
             char addressBuffer[INET_ADDRSTRLEN];
             inet_ntop(AF_INET, tmpAddrPtr, addressBuffer, INET_ADDRSTRLEN);
             if (strlen(ipAddr) + strlen(addressBuffer) < MAX_LENGTH - )
             {
                 if (strlen(ipAddr) > )
                 {
                      strcat(ipAddr, ";");
                 }
                 strcat(ipAddr, addressBuffer);
             }
             else
             {
                 printf("Too many ips!\n");
                 break;
             }
         }
         //else if (ifaddrstruct->ifa_addr->sa_family == af_inet6) { // check it is ip6

         /* deal ip6 addr */
         //    tmpaddrptr = &((struct sockaddr_in *)ifaddrstruct->ifa_addr)->sin_addr;
         //    char addressbuffer[inet6_addrstrlen];
         //    inet_ntop(af_inet6, tmpaddrptr, addressbuffer, inet6_addrstrlen);

         //}
         iter = iter->ifa_next;
     }
     //releas the struct
     freeifaddrs(ifAddrStruct);

     printf("The ips: %s\n", ipAddr);

     return ;
 }

效果：