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InternetCheckConnection function

Applies to: desktop apps only

Allows an application to check if a connection to the Internet can be established.

Syntax

Copy

BOOL InternetCheckConnection(
  __in  LPCTSTR lpszUrl,
  __in  DWORD dwFlags,
  __in  DWORD dwReserved
);

Parameters

lpszUrl [in]

Pointer to a null-terminated string that specifies the URL to use to check the connection. This value can be NULL.

dwFlags [in]

Options. FLAG_ICC_FORCE_CONNECTION is the only flag that is currently available. If this flag is set, it forces a connection. A sockets connection is attempted in the following order:

If lpszUrl is non-NULL, the host value is extracted from it and used to ping that specific host.
If lpszUrl is NULL and there is an entry in the internal server database for the nearest server, the host value is extracted from the entry and used to ping that server.

dwReserved [in]

This parameter is reserved and must be 0.

Return value

Returns TRUE if a connection is made successfully, or FALSE otherwise. Use GetLastError to retrieve the error code. ERROR_NOT_CONNECTED is returned by GetLastError if a connection cannot be made or if the sockets database is unconditionally offline.

Remarks

Note WinINet does not support server implementations. In addition, it should not be used from a service. For server implementations or services use Microsoft Windows HTTP Services (WinHTTP).

Requirements

Minimum supported client	Windows 2000 Professional
Minimum supported server	Windows 2000 Server
Header	Wininet.h
Library	Wininet.lib
DLL	Wininet.dll
Unicode and ANSI names	InternetCheckConnectionW (Unicode) and InternetCheckConnectionA (ANSI)

'Will check to see if user is online, if not close program
    Public Declare Function InternetGetConnectedStateEx Lib "wininet.dll" (ByRef lpdwFlags As Long, ByVal lpszConnectionName As String, ByVal dwNameLen As Integer, ByVal dwReserved As Long) As Long

    Public Function CheckInternetConnection() As Boolean

        Dim aux As String = Nothing

        Dim r As Long = Nothing

        r = InternetGetConnectedStateEx(Nothing, aux, 254, 0)

        If r = 1 Then

            CheckInternetConnection = True

        Else

            CheckInternetConnection = False
            MessageBox.Show("You must be online to access this content")
        End If
        Return CheckInternetConnection
    End Function

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