' FB 1.05.0 Win64

Dim a(65 to 90) As Integer  ' array to hold frequency of each letter, all elements zero initially
Dim fileName As String = "input.txt"
Dim s As String
Dim i As Integer
Open fileName For Input As #1

While Not Eof(1)
  Line Input #1, s
  s = UCase(s)
  For i = 0 To Len(s) - 1
    a(s[i]) += 1
  Next
Wend

Close #1

Print "The frequency of each letter in the file "; fileName; " is as follows:"
Print
For i = 65 To 90
  If a(i) > 0 Then
    Print Chr(i); " : "; a(i)
  End If
Next
Print
Print "Press any key to quit"
Sleep