Question

vb怎么判断网络是否已经连接上？

Answer 1

GetHostbyName API可获取域名对应的IP地址,当没有联网状态将会返回一个错误值。所以可利用它来判断是否联网。

Private Sub Form_Load()
If IsConnectedState Then
MsgBox "连接网络"
Else
MsgBox "没有联网"
End If
End Sub

VBScript code复制代码

Option Explicit

Private Type WSADATA
wversion As Integer
wHighVersion As Integer
szDescription(0 To 256) As Byte
szSystemStatus(0 To 128) As Byte
iMaxSockets As Integer
iMaxUdpDg As Integer
lpszVendorInfo As Long
End Type

Private Declare Function WSAStartup Lib "WSOCK32.DLL" (ByVal wVersionRequired As Integer, lpWSAData As WSADATA) As Long
Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long
Private Declare Function gethostbyname Lib "WSOCK32.DLL" (ByVal szHostname As String) As Long
Private Const WS_VERSION_REQD = &H101

Public Function IsConnectedState() As Boolean
Dim udtWSAD As WSADATA
Call WSAStartup(WS_VERSION_REQD, udtWSAD)
IsConnectedState = CBool(gethostbyname("www.baidu.com"))
Call WSACleanup
End Function