获得本机IP地址

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/types.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>

int getlocalip(char* outip)
{
	int i=0;
	int sockfd;
	struct ifconf ifconf;
	char buf[512];
	struct ifreq *ifreq;
	char* ip;
	//初始化ifconf
	ifconf.ifc_len = 512;
	ifconf.ifc_buf = buf;

	if((sockfd = socket(AF_INET, SOCK_DGRAM, 0))<0){
		return -1;
	}
	ioctl(sockfd, SIOCGIFCONF, &ifconf);    //获取所有接口信息
	close(sockfd);
	//接下来一个一个的获取IP地址
	ifreq = (struct ifreq*)buf;
	
	for(i=(ifconf.ifc_len/sizeof(struct ifreq)); i>0;i--){
		ip = inet_ntoa(((struct sockaddr_in*)&(ifreq->ifr_addr))->sin_addr);

		if(strcmp(ip,"127.0.0.1")==0){  //排除127.0.0.1，继续下一个
			ifreq++;
			continue;
		}
		strcpy(outip,ip);
		return 0;
	}

	return -1;
}

int main(void)
{
	char ip[20];
	if ( getlocalip(ip) == 0 ){
		printf("%s\n",ip );
	}else{
		printf("xxxxx\n");
	}
}