[RESOLVED] Detecting Drive Letter of USB Drive

[chris128]

So how does one get this code to work with
Option explicit = On
Option strict = On

There are many problems with them set to On that will not allow this code to compile.

Just do what Option Strict tells you to do to correct the errors I just turned it on and fixed them (and tidied up a couple of little things in the code) - see code below:

Imports System.Runtime.InteropServices
 
Public Class Form1
 
    Private Const WM_DEVICECHANGE As Integer = &H219
    Private Const DBT_DEVICEARRIVAL As Integer = &H8000
    Private Const DBT_DEVTYP_VOLUME As Integer = &H2
 
    'Device information structure
    Public Structure DEV_BROADCAST_HDR
        Public dbch_size As Int32
        Public dbch_devicetype As Int32
        Public dbch_reserved As Int32
    End Structure
 
    'Volume information Structure
    Private Structure DEV_BROADCAST_VOLUME
        Public dbcv_size As Int32
        Public dbcv_devicetype As Int32
        Public dbcv_reserved As Int32
        Public dbcv_unitmask As Int32
        Public dbcv_flags As Int16
    End Structure
 
    'Function that gets the drive letter from the unit mask
    Private Function GetDriveLetterFromMask(ByRef Unit As Int32) As Char
        Dim i As Integer
        For i = 0 To 25
            If CBool(Unit And i) Then Exit For
            Unit = Unit >> 1
        Next
        Return Chr(i + 1 + Asc("A"))
    End Function
 
    'Override message processing to check for the DEVICECHANGE message
    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = WM_DEVICECHANGE Then
            If CInt(m.WParam) = DBT_DEVICEARRIVAL Then
                Dim DeviceInfo As DEV_BROADCAST_HDR
                DeviceInfo = DirectCast(Marshal.PtrToStructure(m.LParam, GetType(DEV_BROADCAST_HDR)), DEV_BROADCAST_HDR)
                If DeviceInfo.dbch_devicetype = DBT_DEVTYP_VOLUME Then
                    Dim Volume As DEV_BROADCAST_VOLUME
                    Volume = DirectCast(Marshal.PtrToStructure(m.LParam, GetType(DEV_BROADCAST_VOLUME)), DEV_BROADCAST_VOLUME)
                    Dim DriveLetter As String = (GetDriveLetterFromMask(Volume.dbcv_unitmask) & ":\")
                    If IO.File.Exists(IO.Path.Combine(DriveLetter, "test.txt")) Then
                        '<<<< The test file has been found >>>>
                        MessageBox.Show("Found test file")
                    Else
                        '<<<< Test file has not been found >>>>
                        MessageBox.Show("Could not find test file")
 
                    End If
                End If
            End If
        End If
        MyBase.WndProc(m)
    End Sub
 
End Class