网络编程获得本机IP

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/socket.h>
#include<errno.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<ctype.h>
#include<netdb.h>
#define ERR_EXIT(m) do{perror(m);exit(EXIT_FAILURE);}while(0)
int main()
{
	char host[100];
	if (gethostname(host, sizeof(host)) < 0)ERR_EXIT("gethostname");
	struct hostent *hp;
	if ((hp = gethostbyname(host)) == NULL)ERR_EXIT("gethostbyname");
	int i = 0;
	while (hp->h_addr_list[i] != NULL)
	{
		printf("%s\n", inet_ntoa(*(struct in_addr*)hp->h_addr_list[i]));
		i++;
	}
}