Private Sub Command1_Click()

  Dim a(65 To 122) As Integer

  Dim i As Integer, ch As String, count As Integer

  Dim Max As Integer, Maxi As Integer, flag As Boolean

  List1.Clear

  flag = False

  count = 0

  s = Text1.Text

  For i = 1 To Len(s)

     ch = Mid(s, i, 1)

     If ch>= "a" And ch<= "z" Or ch>= "A" And ch<= "Z" Then

        a(Asc(ch)) =

        If flag = False Then

           count = count + 1

           flag = True

        End If

     Else

     End If

  Next i

  Max = 0: Maxi = 0

  For i = 65 To 122     ’A的ASCII码值为65，a的ASCII码值为97

    If a(i) > 0 Then

        List1.AddItem Chr(i) + ":  " + Str(a(i))

    End If

    If a(i) > Max Then

       Max = a(i)

       Maxi = i

    End If

  Next i

  Label1.Caption = "频率最高字母：" + 

  Label2.Caption = "共有单词数：" + Str(count) + "个"

End Sub