SOCK连接错误???

#include <stdio.h>
#include <winsock.h>

int doit(int rgc,char** rgv)
{
char ac[80];
struct hostent* phe;
struct in_addr addr;
int i;
if(gethostname(ac,sizeof(ac))==SOCKET_ERROR)
{
printf("error %d when getting local hostname.\n",WSAGetLastError());
return 1;
}
printf("the host name is:%s\n",ac);
phe=gethostbyname(ac);
if(phe==0)
{
printf("error!bad host lookup.\n");
return 1;
}
for (i=0;phe->h_addr_list[i]!=0;++i)
{
memcpy(&addr,phe->h_addr_list[i],sizeof(struct in_addr));
printf("address %d is %s.\n",i,inet_ntoa(addr));
}
return 0;
}
int main(int argc,char* argv[])
{
WSADATA wsadata;
int retval;
if(WSAStartup(MAKEWORD(1,1),&wsadata)!=0)
{
return 255;
}
retval=doit(argc,argv);
WSACleanup();
return retval;
}

出现
Linking...
test2.obj : error LNK2001: unresolved external symbol _inet_ntoa@4
test2.obj : error LNK2001: unresolved external symbol _gethostbyname@4
test2.obj : error LNK2001: unresolved external symbol _WSAGetLastError@0
test2.obj : error LNK2001: unresolved external symbol _gethostname@8
test2.obj : error LNK2001: unresolved external symbol _WSACleanup@0
test2.obj : error LNK2001: unresolved external symbol _WSAStartup@8
Debug/test2.exe : fatal error LNK1120: 6 unresolved externals
Error executing link.exe.

test2.exe - 7 error(s), 0 warning(s)

该如何解决呢?