How to: Determine a File's Extension in Visual Basic

Retrieve the file path or name of the file and the Split function to determine the extension by supplying the delimiter. This example uses the GetFiles method to return the collection of file names in the directory testDirectory and reports each file's extension.

For Each foundFile As String In
My.Computer.FileSystem.GetFiles("C:\TestDir")
    Dim check As String =
    System.IO.Path.GetExtension(foundFile)
    MsgBox("The file extension is " & check)
Next