IP扫描；SendARP() 查询本地网络在线电脑IP，MAC，以及获得主机名。

#include <windows.h>
#include <stdio.h>
#include <iphlpapi.h>
#include <winsock.h>
#pragma comment(lib, "ws2_32")
#pragma comment(lib, "iphlpapi")

int main()
{
 WORD wVersionRequested;
 WSADATA wsaData;
 int err;
 
 wVersionRequested = MAKEWORD( 2, 2 );
 
 err = WSAStartup( wVersionRequested, &wsaData );
 if ( err != 0 )
 {
  return -1;
 }

    HRESULT hr;
    ULONG   pulMac[2];
    ULONG   ulLen;

 in_addr beginaddr, endaddr;   //
 unsigned long be, en;
 char badd[16]={0};  
 char eadd[16]={0};
 char add[16]={0};
 char name[30]={0};
 hostent *pht=NULL;
 printf("输入起始ip地址：");
 scanf("%16s",badd);
 printf("输入终止ip地址：");
 scanf("%16s",eadd);

 beginaddr.S_un.S_addr = inet_addr(badd);
 endaddr.S_un.S_addr = inet_addr(eadd);
 be = ntohl(beginaddr.S_un.S_addr);
 en = ntohl(endaddr.S_un.S_addr);
 

 printf("%-18s %-20s %-20s/n", "IP", "NAME", "MAC");

 while(be<=en)
 {
  ulLen = 6;
  hr = SendARP(beginaddr.S_un.S_addr, 0, pulMac, &ulLen);
  if(hr == NO_ERROR)
  {
   memcpy(add,inet_ntoa(beginaddr),16);
   pht = gethostbyaddr((char*)&beginaddr, sizeof(beginaddr), AF_INET);
   if (pht != NULL)
   {
    size_t i, j;
    char * szMac = new char[ulLen*3];
    PBYTE pbHexMac = (PBYTE) pulMac;
    for (i = 0, j = 0; i < ulLen - 1; ++i) {
     j += sprintf (szMac + j, "%02X:", pbHexMac[i]);
    }

    sprintf (szMac + j, "%02X", pbHexMac[i]);

    memcpy(name, pht->h_name, 30);   
    printf("%-18s %-20s %-20sis online./n", add, name, szMac);
    delete [] szMac;
   }
   be++;
   beginaddr.S_un.S_addr = htonl(be);
  }
  else
  {
   be++;
   beginaddr.S_un.S_addr = htonl(be);
   continue;
  }

 }
    
 
 WSACleanup( );

 system("pause");
    return 0;
}