实验3 VB.docx

Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Dim x%, y%
x = EventArgs) Handles
If Val() Mod 2 <> 0 Then MsgBox("输入数字不是偶数，请重新输入") = ""
()
End If End Sub
Private Sub TextBox1_TextChanged(ByVal sender As , ByVal e As ) Handles
If Val() < 0 Then
MsgBox("输入数字为负数，请重新输入") = ""
() End If
End Sub End Class
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Dim i%
= Val() = Val() = Trim() Select Case
Case "+"
= Val() + Val() Case "-"
= Val() - Val() Case "*"
= Val() * Val()
Case "/"
If Val() = 0 Then
i = MsgBox("分母为 0", + 48, "警告")
If i = Then Close()
= "" ()
Else
= Val() / Val()
End If End If
End Select
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles End
End