Question

VB2010中USB接口开发，在遍历USB设备时遇到问题

Public Declare Function HidD_GetHidGuid Lib "hid.dll" (ByRef HidGuid As GUID) As Long

Public Structure GUID
Dim data1 As Long
Dim data2 As Integer
Dim data3 As Integer
Dim data4() As Byte
End Structure

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim HidGuid As GUID
Dim DeviceInfoSet As Long
Dim vbNullString As String = Nothing

Result = HidD_GetHidGuid(HidGuid) 这里HidGuid出现NULL引用异常
End Sub

初步估计GUID这个结构体初始化不正确，望有经验的高手指点一二……

Answer 1

对你的API函数不了解，不予置评，但是要指出来的是：VB2010本身支持GUID类型数据，不需要你用结构体定义：
Dim HidGuid As Guid

删除掉你自定义的GUID结构体，用系统本身的Guid数据类型就好了

Answer 2

对不起，帮不了你！