#include <stdio.h>   
#include <stdlib.h>   
#include <error.h>   
#include <string.h>   
#include <netdb.h>   
#include <sys/types.h>   
#include <netinet/in.h>   
#include <sys/socket.h>   
#include <unistd.h>   
#include <sys/ioctl.h> 
#include <arpa/inet.h>   
#include <net/if_arp.h> 
#include <net/if.h>   
#include <arpa/inet.h>  
 
int main(int argc, char *argv[])  
 
{    
    char ipbuf[16];   
    getlocaip(ipbuf);       
    printf("loca ip = %s/n", ipbuf);      
    exit(0);       
}   
   
int getlocaip(char *ip)    
{   
    int sockfd;      
    if(-1 == (sockfd = socket(PF_INET, SOCK_STREAM, 0)))   
    {   
        perror( "socket" );     
        return -1;   
   }   
  
    struct ifreq req;     
    struct sockaddr_in *host;     
    bzero(&req, sizeof(struct ifreq));     
    strcpy(req.ifr_name, "eth0");     
    ioctl(sockfd, SIOCGIFADDR, &req);    
    host = (struct sockaddr_in*)&req.ifr_addr;    
    strcpy(ip, inet_ntoa(host->sin_addr));     
    close(sockfd);     
    return 1;    

} 

*********************************************************************************

//获取本地IP地址

QString GetLocalIp()  
{  
 
    int sock_get_ip;  
    char ipaddr[50];  
 
    struct   sockaddr_in *sin;  
    struct   ifreq ifr_ip;     
 
    if ((sock_get_ip=socket(AF_INET, SOCK_STREAM, 0)) == -1)  
    {  
         printf("socket create failse...GetLocalIp!/n");  
         return "";  
    }  
     
    memset(&ifr_ip, 0, sizeof(ifr_ip));     
    strncpy(ifr_ip.ifr_name, "eth0", sizeof(ifr_ip.ifr_name) - 1);     
   
    if( ioctl( sock_get_ip, SIOCGIFADDR, &ifr_ip) < 0 )     
    {     
         return "";     
    }       
    sin = (struct sockaddr_in *)&ifr_ip.ifr_addr;     
    strcpy(ipaddr,inet_ntoa(sin->sin_addr));         
      
    printf("local ip:%s /n",ipaddr);      
    close( sock_get_ip );  
      
    return QString( ipaddr );  
}  
 

//修改本机IP地址的函数

int SetLocalIp( const char *ipaddr )  
{  
 
    int sock_set_ip;  
      
    struct sockaddr_in sin_set_ip;  
    struct ifreq ifr_set_ip;  
 
    bzero( &ifr_set_ip,sizeof(ifr_set_ip));  
   
    if( ipaddr == NULL )  
        return -1;  
 
    if(sock_set_ip = socket( AF_INET, SOCK_STREAM, 0 ) == -1);  
    {  
        perror("socket create failse...SetLocalIp!/n");  
        return -1;  
    }  
   
    memset( &sin_set_ip, 0, sizeof(sin_set_ip));  
    strncpy(ifr_set_ip.ifr_name, "eth0", sizeof(ifr_set_ip.ifr_name)-1);     
      
    sin_set_ip.sin_family = AF_INET;  
    sin_set_ip.sin_addr.s_addr = inet_addr(ipaddr);  
    memcpy( &ifr_set_ip.ifr_addr, &sin_set_ip, sizeof(sin_set_ip));  
 
    if( ioctl( sock_set_ip, SIOCSIFADDR, &ifr_set_ip) < 0 )  
    {  
        perror( "Not setup interface/n");  
        return -1;  
    }  
 
    //设置激活标志  
    ifr_set_ip.ifr_flags |= IFF_UP |IFF_RUNNING;  
 
    //get the status of the device  
    if( ioctl( sock_set_ip, SIOCSIFFLAGS, &ifr_set_ip ) < 0 )  
    {  
         perror("SIOCSIFFLAGS");  
         return -1;  
    }  
 
    close( sock_set_ip );  
    return 0;  
} 

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/davidge333/archive/2010/01/24/5250566.aspx