请教gethostbyaddr的参数

[dotnba]

struct hostent FAR * gethostbyaddr (
const char FAR * addr,
int len,
int type
);
Parameters
addr
[in] A pointer to an address in network byte order.
len
[in] The length of the address.
type
[in] The type of the address.
addr指的是IP地址吗？如果不是那是什么？
len是不是 strlen(addr)？如果不是那是什么？
若addr是IP地址，那么type是不是 AF_INET?如果不是那是什么？

我对C和winsock都不熟悉。请详细指点。

[zhao_as]

addr指的是IP地址,但不光ip地址，
len是 strlen(addr）
type在用IP的所有协议中是 AF_INET
但这个函数 不光是tcp/ip可以用 用它的多了
既然都不懂 那干吗不从头来看呢？

[dotnba]

您批评的是.
struct hostent * pHostent
pHostent = gethostbyaddr("192.168.192.1",strlen("192.168.192.1"),AF_INET)
if (pHostent == NULL) return "Error";
//Codes Goes Here
//....
为什么我的返回值是NULL呢？

[dotnba]

另外,NetBEUI协议的话，type应该是什么？
type
[in] The type of the address
这个type是不是跟addr有关啊？
如果type == AF_ISO,那么相应的addr是不是应该是另外一种形式，是什么？

[copy_paste]

char* gethost(int s)
{
int size;
char host[30];
struct sockaddr_in addr;
struct hostent *pHostent;
::ZeroMemory(host, sizeof(host));
if (SOCKET_ERROR != getpeername(s, &addr, sizeof(addr)))
{
pHostent = gethostbyaddr(&addr.sin_addr.s_addr, sizeof(int), PF_INET);
if (pHostent)
strcpy(host, pHostent->h_name);
}
return host;
}

[dotnba]

谢谢：问题解决

[kingzai]

//you may initialize socket,such as
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 2 );
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 )
{
/* Tell the user that we could not find a usable */
/* WinSock DLL. */
return 0;
}

[kingzai]

Some applications use the gethostbyaddr( ) function to resolve an IP address to a host name. The gethostbyaddr( ) call uses the following (default) sequence:

Check the hosts file for a matching address entry.
If a DNS server is configured, query it.
Send a NetBIOS Adapter Status Request to the IP address being queried, and if it responds with a list of NetBIOS names registered for the adapter, parse it for the computer name.

[Bind]

INT addr = htonl("127.0.0.1");
hostent* pHost = gethostbyaddr(&addr, sizeof(addr), AF_INET);

[Bind]

SORRY，更正一下
int addr = inet_addr("127.0.0.1");