Microsoft KB Archive/177698

= How To Call WNetConnectionDialog1 and WNetDisconnectDialog1 =

Article ID: 177698

Article Last Modified on 7/11/2005

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APPLIES TO


 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 6.0 Professional Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition
 * Microsoft Visual Basic 6.0 Enterprise Edition
 * Microsoft Platform Software Development Kit-January 2000 Edition

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This article was previously published under Q177698



SUMMARY
The functions WNetConnectionDialog1 and WNetDisconnectDialog1 are very useful for connecting and disconnecting from remote resources. The functions take parameters that allow you to change the default values of the connect and disconnect dialogs before calling them.

They also provide a common set of error-handling messages to the user automatically.

This article demonstrates how to use some of these functions from 32-Bit Visual Basic. These functions are available on Windows 2000, Windows NT, Windows 95, Windows 98, and Windows Me.



MORE INFORMATION
The hardest part of getting these functions working is getting the strings and the NETRESOURCE structure setup in the CONNECTDLGSTRUCT. Fortunately, there are only a few strings in the DISCDLGSTRUCT structure.

 Create a new project with two CommandButtons on the main form. Name the buttons cmdConnectDlg and cmdDisconnectDlg . Add a Textbox to the form and name it txtDisconnect .  Place the following code in the form: Option Explicit

Private Const CONNDLG_RO_PATH = &H1   'Resource path should be                                             'read-only. Private Const CONNDLG_CONN_POINT = &H2 'Netware-style movable 'connection-point enabled. Private Const CONNDLG_USE_MRU = &H4   'Use MRU combobox Private Const CONNDLG_HIDE_BOX = &H8  'Hide persistent connect 'check box. '/*     ' * NOTE:  Set, at most, one of the below flags. If neither flag is     ' *        set, then the persistence is set to whatever the user ' *       chose during a previous connection. '     Private Const CONNDLG_PERSIST = &H10     'Force persistent 'connection. Private Const CONNDLG_NOT_PERSIST = &H20 'Persistent not allowed. ' */

Private Const DISC_UPDATE_PROFILE = &H1 'Remove persistent 'connection. Private Const DISC_NO_FORCE = &H40      'Don't force the disconnect 'if files are still open. Private Const RESOURCETYPE_DISK = &H1 Private Const NO_ERROR = 0 Private Const WN_SUCCESS = NO_ERROR

Private Declare Function MapDrive Lib "mpr.dll" Alias _ "WNetConnectionDialog1A" ( _        lpConnectDlgStruct As Any) As Long Private Declare Function UnMapDrive Lib "mpr.dll" Alias _ "WNetDisconnectDialog1A" ( _        lpDiscDlgStruct As Any) As Long

Private Type CONNECTDLGSTRUCT cbStructure As Long hwndOwner As Long lpConnRes As Long dwFlags As Long dwDevNum As Long End Type

Private Type DISCDLGSTRUCT cbStructure As Long hwndOwner As Long lpLocalName As String lpRemoteName As String dwFlags As Long End Type

Private Type NETRESOURCE dwScope As Long dwType As Long dwDisplayType As Long dwUsage As Long lpLocalName As Long lpRemoteName As String lpComment As Long lpProvider As Long End Type

'Memory Management Routines & Constants Private Const GMEM_FIXED = &H0 Private Const GMEM_ZEROINIT = &H40 Private Const GPTR = (GMEM_FIXED Or GMEM_ZEROINIT) Private Declare Function GlobalAlloc Lib "kernel32" ( _        ByVal wFlags As Long, _         ByVal dwBytes As Long) As Long Private Declare Function GlobalFree Lib "kernel32" ( _        ByVal hMem As Long) As Long Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _ (lpOut As Any, _        lpIn As Any, _         ByVal cbCopy As Long)

Private Sub cmdConnectDlg_Click Dim cs As CONNECTDLGSTRUCT, nr As NETRESOURCE, res As Long 'Setup the NETRESOURCE structure. nr.lpRemoteName = "\\servername\sharename" nr.dwType = RESOURCETYPE_DISK

With cs 'Setup the connection dialog structure. .cbStructure = LenB(cs) .hwndOwner = Me.hWnd .lpConnRes = GlobalAlloc(GPTR, LenB(nr)) CopyMemory ByVal .lpConnRes, nr, LenB(nr) .dwFlags = CONNDLG_USE_MRU Or _ CONNDLG_HIDE_BOX Or _ CONNDLG_NOT_PERSIST End With

res = MapDrive(cs) 'Call WNetConnectionDialog1. If res = WN_SUCCESS Then MsgBox "MapDrive Succeeded." txtDisconnect.Text = Chr$(cs.dwDevNum + 64) & ":" Else MsgBox "Error: " & Err.LastDllError End If        GlobalFree (cs.lpConnRes) End Sub

Private Sub cmdDisconnectDlg_Click Dim ds As DISCDLGSTRUCT, res As Long 'Setup the disconnect dialog structure. ds.cbStructure = LenB(ds) ds.hwndOwner = Me.hWnd ds.lpLocalName = txtDisconnect.Text ds.dwFlags = DISC_NO_FORCE Or DISC_UPDATE_PROFILE

res = UnMapDrive(ds) 'Call WnetDisconnectDialog1. If res = WN_SUCCESS Then MsgBox "UnMapDrive Succeeded." Else MsgBox "Error: " & Err.LastDllError End If     End Sub

 Run the program. Click the cmdConnectDlg button, and connect to a network share. The drive letter that is connected is placed in the txtDisconnect text box. Now click the cmdDisconnectDlg button. The mapped drive will be disconnected. Click the cmdDisconnectDlg button again: On Windows NT and Windows 2000, an error will be displayed and then the error value will be returned by the WNetDisconnectDialog1 function. Click the cmdConnectDlg button, and pass an invalid server name to the dialog. Another error message will appear explaining the problem and, again, passing the error back to the program.</li></ol>

Keywords: kbhowto kbwnet KB177698

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