53.txt

VB文章集（含API、窗口、数据库、多媒体、系统、文件、等等）

如何检测是否已连接到Internet？
 

声明：

Public Declare Function RasEnumConnections Lib "RasApi32.dll" _
    Alias "RasEnumConnectionsA" (lpRasCon As Any, _
    lpcb As Long, lpcConnections As Long) As Long
Public Declare Function RasGetConnectStatus Lib "RasApi32.dll" _
    Alias "RasGetConnectStatusA" (ByVal hRasCon As Long, _
    lpStatus As Any) As Long
 
Public Const RAS95_MaxEntryName = 256
Public Const RAS95_MaxDeviceType = 16
Public Const RAS95_MaxDeviceName = 32
 
Public Type RASCONN95
    dwSize As Long
    hRasCon As Long
    szEntryName(RAS95_MaxEntryName) As Byte
    szDeviceType(RAS95_MaxDeviceType) As Byte
    szDeviceName(RAS95_MaxDeviceName) As Byte
End Type
 
Public Type RASCONNSTATUS95
    dwSize As Long
    RasConnState As Long
    dwError As Long
    szDeviceType(RAS95_MaxDeviceType) As Byte
    szDeviceName(RAS95_MaxDeviceName) As Byte
End Type

程序：
Private Sub main()
    If IsConnected = True Then
        MsgBox "已连接到Internet！", vbInformation, "提示"
    Else
        MsgBox "未连接到Internet！", vbInformation, "提示"
    End If
End Sub
 
Public Function IsConnected() As Boolean
    Dim TRasCon(255) As RASCONN95
    Dim lg As Long
    Dim lpcon As Long
    Dim RetVal As Long
    Dim Tstatus As RASCONNSTATUS95
    '
    TRasCon(0).dwSize = 412
    lg = 256 * TRasCon(0).dwSize
    '
    RetVal = RasEnumConnections(TRasCon(0), lg, lpcon)
    If RetVal <> 0 Then
        MsgBox "产生错误！", vbInformation, "提示"
        Exit Function
    End If
    '
    Tstatus.dwSize = 160
    RetVal = RasGetConnectStatus(TRasCon(0).hRasCon, Tstatus)
    If Tstatus.RasConnState = &H2000 Then
        IsConnected = True
    Else
        IsConnected = False
    End If
End Function