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vb功能实例介绍。详细、很好的实例说明。

<p>如何检测是否已连接到Internet？</p>
<p> </p>
<p></p>
<p>声明：</p>
<p></p>
<p>Public Declare Function RasEnumConnections Lib "RasApi32.dll" _</p>
<p>    Alias "RasEnumConnectionsA" (lpRasCon As Any, _</p>
<p>    lpcb As Long, lpcConnections As Long) As Long</p>
<p>Public Declare Function RasGetConnectStatus Lib "RasApi32.dll" _</p>
<p>    Alias "RasGetConnectStatusA" (ByVal hRasCon As Long, _</p>
<p>    lpStatus As Any) As Long</p>
<p> </p>
<p>Public Const RAS95_MaxEntryName = 256</p>
<p>Public Const RAS95_MaxDeviceType = 16</p>
<p>Public Const RAS95_MaxDeviceName = 32</p>
<p> </p>
<p>Public Type RASCONN95</p>
<p>    dwSize As Long</p>
<p>    hRasCon As Long</p>
<p>    szEntryName(RAS95_MaxEntryName) As Byte</p>
<p>    szDeviceType(RAS95_MaxDeviceType) As Byte</p>
<p>    szDeviceName(RAS95_MaxDeviceName) As Byte</p>
<p>End Type</p>
<p> </p>
<p>Public Type RASCONNSTATUS95</p>
<p>    dwSize As Long</p>
<p>    RasConnState As Long</p>
<p>    dwError As Long</p>
<p>    szDeviceType(RAS95_MaxDeviceType) As Byte</p>
<p>    szDeviceName(RAS95_MaxDeviceName) As Byte</p>
<p>End Type</p>
<p></p>
<p>程序：</p>
<p>Private Sub main()</p>
<p>    If IsConnected = True Then</p>
<p>        MsgBox "已连接到Internet！", vbInformation, "提示"</p>
<p>    Else</p>
<p>        MsgBox "未连接到Internet！", vbInformation, "提示"</p>
<p>    End If</p>
<p>End Sub</p>
<p> </p>
<p>Public Function IsConnected() As Boolean</p>
<p>    Dim TRasCon(255) As RASCONN95</p>
<p>    Dim lg As Long</p>
<p>    Dim lpcon As Long</p>
<p>    Dim RetVal As Long</p>
<p>    Dim Tstatus As RASCONNSTATUS95</p>
<p>    '</p>
<p>    TRasCon(0).dwSize = 412</p>
<p>    lg = 256 * TRasCon(0).dwSize</p>
<p>    '</p>
<p>    RetVal = RasEnumConnections(TRasCon(0), lg, lpcon)</p>
<p>    If RetVal <> 0 Then</p>
<p>        MsgBox "产生错误！", vbInformation, "提示"</p>
<p>        Exit Function</p>
<p>    End If</p>
<p>    '</p>
<p>    Tstatus.dwSize = 160</p>
<p>    RetVal = RasGetConnectStatus(TRasCon(0).hRasCon, Tstatus)</p>
<p>    If Tstatus.RasConnState = &H2000 Then</p>
<p>        IsConnected = True</p>
<p>    Else</p>
<p>        IsConnected = False</p>
<p>    End If</p>
<p>End Function</p>
<p> </p>