对于那些必须和internet链结才能工作的程序来说，知道当前计算机是否处于链结状态是非常有意义的。当Windows系统处于链结状态时，它会在注册表里改动一个键值，下面的例子告诉你如何读取这个键值，并得知系统是否与internet相连。
＇声明以下函数变量常量:
Public Const ERROR_SUCCESS = 0&
Public Const APINULL = 0&
Public Const HKEY_LOCAL_MACHINE = &H80000002
Public ReturnCode As Long
Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Declare Function RegQueryvalueEx Lib "advapi32.dll" Alias "RegQueryvalueExA" (ByVal hKey As Long, ByVal lpvalueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Any, lpcbData As Long) As Long
＇代码:
Public Function ActiveConnection() As Boolean
Dim hKey As Long
Dim lpSubKey As String
Dim phkResult As Long
Dim lpvalueName As String
Dim lpReserved As Long
Dim lpType As Long
Dim lpData As Long
Dim lpcbData As Long
ActiveConnection = False
lpSubKey = "System\CurrentControlSet\Services\RemoteAccess"
ReturnCode = RegOpenKey(HKEY_LOCAL_MACHINE, lpSubKey, phkResult)
If ReturnCode = ERROR_SUCCESS Then
hKey = phkResult
lpvalueName = "Remote Connection"
lpReserved = APINULL
lpType = APINULL
lpData = APINULL
lpcbData = APINULL
ReturnCode = RegQueryvalueEx(hKey, lpvalueName, lpReserved, lpType, ByVal lpData, lpcbData)
lpcbData = Len(lpData)
ReturnCode = RegQueryvalueEx(hKey, lpvalueName, lpReserved, lpType, lpData, lpcbData)
If ReturnCode = ERROR_SUCCESS Then
If lpData = 0 Then
ActiveConnection = False
Else
ActiveConnection = True
End If
End If
RegCloseKey (hKey)
End If
End Function
下面是使用以上代码的例子:
If ActiveConnection = True Then
Call MsgBox("现在处于链结状态。", vbInformation)
Else
Call MsgBox("现在处于断开状态。", vbInformation)
End If