为什么我的情况没有按预期工作？

Question

我的状况并不好，那是什么问题？任何人都可以帮我吗？

Public Class Form5 

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged 
     Dim a As Integer 
     If TextBox1.Text = "" Then 
      TextBox2.Text = "" 
     End If 

     a = Val(TextBox1.Text) 
     If TextBox1.Text = "" Then 
      TextBox2.Text = "" 
     ElseIf (a < 4.9) Then 
      TextBox2.Text = ("Little or No Damage") 
     ElseIf (a <= 5 AndAlso a >= 5.5) Then 
      TextBox2.Text = ("Some Damage") 
     ElseIf (a <= 5.6 And a >= 6.5) Then 
      TextBox2.Text = ("Serious Damage") 
     ElseIf (a <= 6.6 And a >= 7.5) Then 
      TextBox2.Text = ("Disaster") 
     ElseIf (a > 7.5) Then 
      TextBox2.Text = ("Catasthrope") 
     End If 

    End Sub 
End Class 

Answer 1

你只混了<=和>=。

但它会更易读且不易出错，如果你会使用Select代替，例如：

Select Case a 
    Case Is < 4.9 
     TextBox2.Text= "Little or No Damage" 
    Case 5 To 5.5 
     TextBox2.Text= "Some Damage" 
    Case 5.6 To 6.5 
     TextBox2.Text= "Serious Damage" 
    Case 6.6 To 7.5 
     TextBox2.Text= "Disaster" 
    Case Is > 7.5 
     TextBox2.Text= "Catasthrope" 
End Select