判断该年是否为闰年，并根据给定的月份判断该月有多少天

闰年是可被4整除不能被100整除，即：y Mod 4=0  And y Mod100 <>0 Or y Mod 400=0

      Private Sub Command1_Click()

           Dim y As Integer, m As Integer, days As Integer

           Dim leap As Boolean

          If   Text1.Text=""  Then MsgBox "请输入正确的年份，重试!" :Exit Sub

          If   Text2.Text=""  Or Val (Text2.Text)<0 Or Val (Text2.Text)>12 Then MsgBox "请输入正确的年份，重试!" :Exit Sub

                 y=Val (Text1.Text)

                m=Val (Text2.Text)

        If  (y Mod 4=0 And y Mod 100<>0) Or (y Mod 400=0) Then

              leap=True

        Else

       Select Case m

           Case 1,3,5,7,8,10,12

               days=31

          Case 4,6,9,11

              days=30

           Case 2

                If leap Then

                  days=29

               Else

                  days=28

               End If

        End Select

       Label4.Caption=y & "年" & IIf (leap,"是", "不是") & "闰年," & Chr(13) & m & "月有" & days & “天"

          Text1.SetFocus

      End Sub

    Private Sub Command2_Click()

         Text1.SetFocus

        Text1.text= " "

        Text2.text= " "

       Label4.Caption = " "

  End Sub

心得体会：应知道布尔型只有True 和False 两种，学会使用Select Case语句，以实现多分支选择。