How to get IP address?

monsieur_jj

Hi all How do I get my IP address by code? Whats the shortest way possible? I tried getenv but I found out not every computer has their IP add in their environment variables. Thanks, Jayjay

kcynic

get host name first and then get the details. The following code might be helpful: char host_name[128]; hostent* host; gethostname(host_name,128); host = gethostbyname(host_name); printf("The local host: Address : %s\n", inet_ntoa(*(struct in_addr*)host->h_addr)); Regards

monsieur_jj

Hi kcynic, the gethostname didnt fill up the host_name. Is there a requirement before using your code? Thanks, Jayjay

kcynic

did you forget to call WSAStartup？

monsieur_jj

Hi kcynic, It is working now however there is no h_addr just h_addr_list[0] in the struct of hostent, I still can't find the ipadd. Whats your advise on this? Thanks, Jayjay

enhzflep

Hmm, interesting. With the following code compiled and linked with wsock32, I get an output of Hostname: xpDesktop The local host: Address : 210.84.23.xxx Press any key to continue . . .

#include <windows.h>
#include <winsock2.h>
#include <stdio.h>

int main()
{
char host_name[128];
hostent* host;
WORD verRequested = MAKEWORD(1,1), err; // version 1.1
WSADATA wsaData;
err = WSAStartup(verRequested, &wsaData);
gethostname(host_name,128);
printf("Hostname: %s\n", host_name);
host = gethostbyname(host_name);
printf("The local host: Address : %s\n", inet_ntoa(*(struct in_addr*)host->h_addr));
WSACleanup();
system("pause");
}

kcynic

in winsock2.h: struct hostent { char FAR * h_name; /* official name of host */ char FAR * FAR * h_aliases; /* alias list */ short h_addrtype; /* host address type */ short h_length; /* length of address */ char FAR * FAR * h_addr_list; /* list of addresses */ #define h_addr h_addr_list[0] /* address, for backward compat */ }; if you call WSAStartup first, you should get the result.

monsieur_jj

Actually yes i called WSAStartup first The host name is jdeguzman however the h_addr_list[0] value is

*jdeguzman

which i dont get why it returns that instead my ip address. Thanks, Jayjay

kcynic

yes, my result is similar to yours. and the ip result is returned by calling inet_ntoa function. what's you code look like? of course you should check all the callings successful or not. msdn will give you more details i think.

monsieur_jj

Its all working now Thanks!

Hamid Taebi

And see Getting Addresses IP informations[^] of course its more of your answer but it has good info for you. :)

monsieur_jj

This is my function for you all:

char* GetIpAddress()
{
WSADATA wsaData;

	char host\_name\[128\];    
	hostent\* host;    
	WORD verRequested = MAKEWORD(1,1), err;  
	err = WSAStartup(verRequested, &wsaData);    
	gethostname(host\_name,128);      
	host = gethostbyname(host\_name);   
	host->h\_addr\_list\[0\];  
	WSACleanup();    
	
	return inet\_ntoa(\*(struct in\_addr\*)host->h\_addr);

}