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Editor to share with you the VB.NET network application connectivity detection example analysis, I believe that most people do not know much about it, so share this article for your reference, I hope you will learn a lot after reading this article, let's go to know it!

VB.NET Network Application Connectivity Detection

Many applications often need to network directly in the program in order to perform some necessary processing (such as online registration and online help, etc.), which requires us to establish some connections in the program. Many software launch browsers to find the URL without knowing whether the user is connected to the Internet, and the result can only find a wrong web page, which is a waste of user time and has no effect. If the application can automatically determine whether the user is online before looking up the web page, it will save a lot of time and improve the efficiency of the program.

The following is the VB 6 code for network connectivity detection:

Private Sub Form_Load () If IsConnected = TRUE Then MsgBox ("you are already connected to Internet!") End If If IsConnected = FALSE Then MsgBox ("you are not connected to Internet!") End If End Sub Option Explicit / * related API statements and definitions * / 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 / * setting of constants and variables * / 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 The End Type / * function IsConnected returns the connected state If True, it means connected * / Public Function IsConnected () As Boolean Dim TRasCon (255th) As RASCONN95 Dim lg As Long Dim lpcon As Long Dim RetVal As Long Dim Tstatus As RASCONNSTATUS95 TRasCon (0). DwSize = 412lg = 256* TRasCon (0). DwSize RetVal = RasEnumConnections (TRasCon (0), lg, lpcon) If RetVal 0 Then MsgBox "error" Exit Function End If Tstatus.dwSize = 160RetVal = RasGetConnectStatus (TRasCon (0) .hRasCon) Tstatus) If Tstatus.RasConnState = & H2000 Then IsConnected = TRUE Else IsConnected = FALSE End If End Function above are all the contents of the article "sample Analysis of Connectivity Detection for VB.NET Network applications" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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