Source code in the freebasic programming language

' FB 1.05.0 Win64

Function isOrdered(s As Const String) As Boolean
  If Len(s) <= 1 Then Return True
  For i As Integer = 1 To Len(s) - 1
    If s[i] < s[i - 1] Then Return False
  Next 
  Return True
End Function

Dim words() As String
Dim word As String
Dim maxLength As Integer = 0
Dim count As Integer = 0 
Open "undict.txt" For Input As #1
While Not Eof(1)
  Line Input #1, word
  If isOrdered(word) Then
    If Len(word) = maxLength Then
      Redim Preserve words(0 To count)
      words(count) = word
      count += 1
    ElseIf Len(word) > maxLength Then
      Erase words
      maxLength = Len(word)
      Redim words(0 To 0)
      words(0) = word
      count = 1
    End If
  End If
Wend

Close #1

Print "The ordered words with the longest length ("; Str(maxLength); ") in undict.txt are :"
Print
For i As Integer = 0 To UBound(words)
  Print words(i)
Next
Print
Print "Press any key to quit"
Sleep