なぜ私のメッセージボックスがここに

Question

が動作していないことは、私のコードです：それはdblpreviousがdblcurrentより大きい場合invalidinputを呼び出すためのものです が、それは私が知っている代わりに、負の出力を示しているその単純なことになった

Public Class Form1 
'names the the class veriables 
Dim dblCurrent As Double 
Dim dblPervious As Double 
Private Sub invalidinput() 
    Const Message As String = "check your input" 
    Const title As String = " Attention!" 
    Const buttons = MessageBoxButtons.OK 
    MessageBox.Show(Message, title, buttons) 
End Sub 

Private Sub Total() 

    Dim dblTotalP As Double 
    Dim dblTotalG As Double 
    Const dblPerGC As Double = 5.15 
    Const dbltMinC As Double = 19.69 

    'stores the veriables 
    Double.TryParse(txtCurrentreading.Text, dblCurrent) 
    Double.TryParse(txtPerivousreading.Text, dblPervious) 
    dblTotalG = dblCurrent - dblPervious 
    dblTotalP = dblTotalG/1000 * dblPerGC 
    If dblTotalP < dbltMinC Then 
     dblTotalP = dbltMinC 
    End If 


    'displays totals 
    lblTotalG.Text = dblTotalG 
    lblTotalP.Text = dblTotalP.ToString("C2") 
End Sub 

Private Sub bntExit_Click(sender As Object, e As EventArgs) Handles bntExit.Click 
    Me.Close() 

End Sub 

Private Sub txtCurrentreading_keypress(sender As Object, e As KeyPressEventArgs) Handles txtCurrentreading.KeyPress 
    'allows text box to accept only numbers and the back space key 

    If (e.KeyChar < "0" OrElse e.KeyChar > "9") AndAlso e.KeyChar <> ControlChars.Back Then 
     e.Handled = True 
    End If 

End Sub 

Private Sub txtPerivousreading_keypess(sender As Object, e As KeyPressEventArgs) Handles txtPerivousreading.KeyPress 
    'allows text box to accept only numbers and the back space key 


    If (e.KeyChar < "0" OrElse e.KeyChar > "9") AndAlso e.KeyChar <> ControlChars.Back Then 
     e.Handled = True 
    End If 

End Sub 

Private Sub bntCalculate_Click(sender As Object, e As EventArgs) Handles bntCalculate.Click 

    'determines which calculations to do 
    If dblCurrent >= dblPervious Then 
     Call Total() 
    ElseIf dblPervious < dblCurrent Then 
     Call invalidinput() 
    End If 
End Sub 
End Class 

Answer 1

dblpreviousが dblcurrent

変化よりも大きい場合にはinvalidinputを呼び出すためのものです：

If dblCurrent >= dblPervious Then 
    Call Total() 
ElseIf dblPervious < dblCurrent Then 
    Call invalidinput() 
End If 

へ：If dblPervious < dblCurrent Thenの他のブロックで

If dblCurrent >= dblPervious Then 
    Call Total() 
Else 
    Call invalidinput() 
End If 

あなたのオリジナルのチェックが直接あなたの要件が規定されるどのような矛盾！ "dblCurrent"が "dblPervious"以上でない場合、 "dblPervious"は "dblCurrent"より大きくなければなりません。したがって、2つ目のチェックを完全に削除することができます。