CountFileCharacters - Counting how many characters of a given type are in a file

' Count how many characters of a given type are in a file
' Example:
'    Dim charCount(255) As Integer
'    CountFileCharacters("c:\test.txt", charCount)
'    Debug.WriteLine("the char 'A' was found " & charCount(Asc("A")) & " times")
'    Debug.WriteLine("the char 'a' was found " & charCount(Asc("a")) & " times")

Sub CountFileCharacters(ByVal filePath As String, ByVal charCount() As Integer)
    Dim i As Integer, acode As Integer
    Dim fs As System.IO.FileStream
    Dim fileLength As Integer = New System.IO.FileInfo(filePath).Length
    Dim content(fileLength - 1) As Byte

    Try
        ' read the file contents in a temporary Byte array
        fs = New System.IO.FileStream(filePath, IO.FileMode.Open)
        fs.Read(content, 0, fs.Length)
    Finally
        If Not fs Is Nothing Then fs.Close()
    End Try

    ' parse the array, update charCount()
    For i = 0 To content.GetUpperBound(0)
        acode = content(i)
        charCount(acode) = charCount(acode) + 1
    Next i
End Sub