Can you help me see if this small network program runs wrong? ?

sjtwenzhou

#include <Windows.h>
#include <stdio.h>
#include "Iphlpapi.h" // Contains the definition of the IP helper function

#pragma comment (lib, "Iphlpapi.lib")
#pragma comment (lib, "WS2_32.lib")

// Global data
u_char g_ucLocalMac [6]; // Local MAC address
DWORD g_dwGatewayIP; // Gateway IP address
DWORD g_dwLocalIP; // Local IP address
DWORD g_dwMask; // Subnet mask
BOOL GetGlobalData ()
{
 PIP_ADAPTER_INFO pAdapterInfo = NULL;
 ULONG ulLen = 0;
 // Apply memory for the adapter structure
 :: GetAdaptersInfo (pAdapterInfo,&ulLen);
 pAdapterInfo = (PIP_ADAPTER_INFO) :: GlobalAlloc (GPTR, ulLen);
 // Get local adapter structure information
 if (:: GetAdaptersInfo (pAdapterInfo,&ulLen) == ERROR_SUCCESS)
 {
Ranch
if (pAdapterInfo! = NULL)
{
memcpy (g_ucLocalMac, pAdapterInfo-> Address, 6);
  g_dwGatewayIP = :: inet_addr (pAdapterInfo-> GatewayList.IpAddress.String);
  g_dwLocalIP = :: inet_addr (pAdapterInfo-> IpAddressList.IpAddress.String);
  g_dwMask = :: inet_addr (pAdapterInfo-> IpAddressList.IpMask.String);
        
}
 }

 printf ("\n ------------------------------- Local host information ------------ ------------\n\n ");
 in_addr in;
 in.S_un.S_addr = g_dwLocalIP;
 printf ("IP Address:% s\n", :: inet_ntoa (in));
 in.S_un.S_addr = g_dwMask;
 printf ("Subnet Mask:% s\n", inet_ntoa (in));
in.S_un.S_addr = g_dwGatewayIP;
printf ("Default Gateway:% s\n", :: inet_ntoa (in));
u_char * p = g_ucLocalMac;
printf ("MAC Address:% 02x-% 02x-% 02x-% 02x-% 02x-% 02x\n", p [0],
p [1], p [2], p [3], p [4], p [5]);
printf ("\n\n");
return true;
}

int main ()
{
GetGlobalData ();
system ("pause");
    return 0;
}

The result is:
------------------------------- Local host information ---------------- ---

        IP Address: 0.0.0.0
     Subnet Mask: 0.0.0.0
Default Gateway: 0.0.0.0
    MAC Address: 00-ff-da-51-62-0a

Please press any key to continue ...

Why are some running results all zeros? This program is an example in the book. Master friends help me see?