Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Dim a() As Char

        Dim i, j, k As Integer

        i =  : j =  : k =

        a = InputBox("请输入字符串", "输入")

        For b As Integer =  To Len(a) -

            Select Case a(b)

                Case "a" To "z"

                    i +=

                Case "A" To "Z"

                    j +=

                Case "" To ""

                    k +=

            End Select

        Next

        Label1.Text = "小写字母： " & i & Chr() & "大学字母： " & j & Chr() & "数字：     " & k

    End Sub

End Class