应该调用WinSock的几个函数。先使用gethostname获得本机的名字，然后使用gethostbyname得到IP地址。下面的例子摘自微软的Knowledge
Base的文章：“Q160215 OWTO: Obtain the Host IP Address Using Windows Sockets”。
1. 启动Visual Basic，将建立Form1。
2. 放置按钮Command1在Form1上。
3. 在 Form1的声明部分放置如下代码:
Private Const WS_VERSION_REQD = &H101
Private Const WS_VERSION_MAJOR = WS_VERSION_REQD \ &H100 And &HFF&
Private Const WS_VERSION_MINOR = WS_VERSION_REQD And &HFF&
Private Const MIN_SOCKETS_REQD = 1
Private Const SOCKET_ERROR = -1
Private Const WSADescription_Len = 256
Private Const WSASYS_Status_Len = 128

Private Type HOSTENT
hName As Long
hAliases As Long
hAddrType As Integer
hLength As Integer
hAddrList As Long
End Type

Private Type WSADATA
wversion As Integer
wHighVersion As Integer
szDescription(0 To WSADescription_Len) As Byte
szSystemStatus(0 To WSASYS_Status_Len) As Byte
iMaxSockets As Integer
iMaxUdpDg As Integer
lpszVendorInfo As Long
End Type

Private Declare Function WSAGetLastError Lib "WSOCK32.DLL" () As Long
Private Declare Function WSAStartup Lib "WSOCK32.DLL" (ByVal _
wVersionRequired&, lpWSAData As WSADATA) As Long
Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long

Private Declare Function gethostname Lib "WSOCK32.DLL" (ByVal hostname$,_
ByVal HostLen as Long) as long
Private Declare Function gethostbyname Lib "WSOCK32.DLL" (ByVal _
hostname$) As Long
Private Declare Sub RtlMoveMemory Lib "KERNEL32" (hpvDest As Any, ByVal_
hpvSource&, ByVal cbCopy&)

Function hibyte(ByVal wParam As Integer)

hibyte = wParam \ &H100 And &HFF&

End Function

Function lobyte(ByVal wParam As Integer)

lobyte = wParam And &HFF&

End Function

Sub SocketsInitialize()
Dim WSAD As WSADATA
Dim iReturn As Integer
Dim sLowByte As String, sHighByte As String, sMsg As String

iReturn = WSAStartup(WS_VERSION_REQD, WSAD)

If iReturn <> 0 Then
MsgBox "Winsock.dll is not responding."
End
End If

If lobyte(WSAD.wversion) WS_VERSION_MAJOR And hibyte(WSAD.wversion) < WS_VERSION_MINOR) Then

sHighByte = Trim$(Str$(hibyte(WSAD.wversion)))
sLowByte = Trim$(Str$(lobyte(WSAD.wversion)))
sMsg = "Windows Sockets version " & sLowByte & "." & sHighByte
sMsg = sMsg & " is not supported by winsock.dll "
MsgBox sMsg
End
End If

'iMaxSockets is not used in winsock 2. So the following check is only
'necessary for winsock 1. If winsock 2 is requested,
'the following check can be skipped.

If WSAD.iMaxSockets < MIN_SOCKETS_REQD Then
sMsg = "This application requires a minimum of "
sMsg = sMsg & Trim$(Str$(MIN_SOCKETS_REQD)) & " supported sockets."
MsgBox sMsg
End
End If

End Sub

Sub SocketsCleanup()
Dim lReturn As Long

lReturn = WSACleanup()

If lReturn <> 0 Then
MsgBox "Socket error " & Trim$(Str$(lReturn)) & " occurred in Cleanup "
End
End If

End Sub

Sub Form_Load()

SocketsInitialize

End Sub

Private Sub Form_Unload(Cancel As Integer)

SocketsCleanup

End Sub

Private Sub Command1_click()
Dim hostname As String * 256
Dim hostent_addr As Long
Dim host As HOSTENT
Dim hostip_addr As Long
Dim temp_ip_address() As Byte
Dim i As Integer
Dim ip_address As String

If gethostname(hostname, 256) = SOCKET_ERROR Then
MsgBox "Windows Sockets error " & Str(WSAGetLastError())
Exit Sub
Else
hostname = Trim$(hostname)
End If

hostent_addr = gethostbyname(hostname)

If hostent_addr = 0 Then
MsgBox "Winsock.dll is not responding."
Exit Sub
End If

RtlMoveMemory host, hostent_addr, LenB(host)
RtlMoveMemory hostip_addr, host.hAddrList, 4

MsgBox hostname

'get all of the IP address if machine is multi-homed

Do
ReDim temp_ip_address(1 To host.hLength)
RtlMoveMemory temp_ip_address(1), hostip_addr, host.hLength

For i = 1 To host.hLength
ip_address = ip_address & temp_ip_address(i) & "."
Next
ip_address = Mid$(ip_address, 1, Len(ip_address) - 1)

MsgBox ip_address

ip_address = ""
host.hAddrList = host.hAddrList + LenB(host.hAddrList)
RtlMoveMemory hostip_addr, host.hAddrList, 4
Loop While (hostip_addr <> 0)

End Sub


4. 按F5键运行程序。
5. 点击Command1获得主机信息。