Question

我正在研究计算器，我想知道是否有人可以提示如何在文本框中显示数字和运算符。我试过自己做但没有成功......

问候，

Pd积。仅提示，而非代码完成。我需要学习！

这是我的代码。

Public Class Form1
Dim FirstNumber As Double
Dim Operation As String
Dim ClearField As Boolean = True

Private Sub AddNumber(NewValue As String)
    If ClearField = True Then Viewer.Text = ""
    Viewer.Text &= NewValue
    ClearField = False

End Sub

'BUTTONS
'Numbers

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    AddNumber("1")

End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    AddNumber("2")
End Sub

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    AddNumber("3")
End Sub

Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
    AddNumber("4")
End Sub

Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
    AddNumber("5")
End Sub

Private Sub Button6_Click(sender As Object, e As EventArgs) Handles Button6.Click
    AddNumber("6")
End Sub

Private Sub Button7_Click(sender As Object, e As EventArgs) Handles Button7.Click
    AddNumber("7")
End Sub

Private Sub Button8_Click(sender As Object, e As EventArgs) Handles Button8.Click
    AddNumber("8")
End Sub

Private Sub Button9_Click(sender As Object, e As EventArgs) Handles Button9.Click
    AddNumber("9")
End Sub

Private Sub Button15_Click(sender As Object, e As EventArgs) Handles Zero.Click
    AddNumber("0")
End Sub

'Buttons "," "del" "clear"

Private Sub Button14_Click(sender As Object, e As EventArgs) Handles Dot.Click
    Viewer.Text = Viewer.Text + ","
End Sub

Private Sub Button17_Click(sender As Object, e As EventArgs) Handles Del.Click
    Viewer.Text = Viewer.Text.Remove(Viewer.Text.Length - 1, 1)
End Sub

Private Sub Clear_Click(sender As Object, e As EventArgs) Handles Clear.Click
    Viewer.Text = ""
End Sub

Private Sub Sum_Click(sender As Object, e As EventArgs) Handles Sum.Click
    FirstNumber = Val(Viewer.Text)
    Operation = "SUM"
    Viewer.Text = ""
End Sub

Private Sub Minus_Click(sender As Object, e As EventArgs) Handles Minus.Click
    FirstNumber = Val(Viewer.Text)
    Operation = "MINUS"
    Viewer.Text = ""
End Sub

Private Sub Multi_Click(sender As Object, e As EventArgs) Handles Multi.Click
    FirstNumber = Val(Viewer.Text)
    Operation = "MULTI"
    Viewer.Text = ""
End Sub

Private Sub Div_Click(sender As Object, e As EventArgs) Handles Div.Click
    FirstNumber = Val(Viewer.Text)
    Operation = "DIV"
    Viewer.Text = ""
End Sub

Private Sub Result_Click(sender As Object, e As EventArgs) Handles Result.Click
    Dim SecondNumber As Double
    Dim Result As Double

    SecondNumber = Val(Viewer.Text)

    'Fx
    If Operation = "SUM" Then
        Result = FirstNumber + SecondNumber
    End If

    If Operation = "MINUS" Then
        Result = FirstNumber - SecondNumber
    End If

    If Operation = "MULTI" Then
        Result = FirstNumber * SecondNumber
    End If

    If Operation = "DIV" Then
        Result = FirstNumber / SecondNumber
    End If

    Viewer.Text = Result
    ClearField = True

End Sub


Private Sub SalirToolStripMenuItem1_Click(sender As Object, e As EventArgs) Handles SalirToolStripMenuItem1.Click
    End
End Sub

结束班

Answer 1

a）不要使用Val

这很糟糕，从长远来看会造成问题。

b）使用枚举：

Enum myOp
   None 
   Adding 
   Subbing
   Divide
   Equals
End Enum

Dim Op As myOp

这些最终具有从0到4的整数值，但您可以按名称引用它们。 Case语句可以减少大多数人认为更容易阅读的代码：

Select Case Op
      Case myOp.Adding
           Result = FirstNumber + SecondNumber

      Case myOp.Subbing
            Result = FirstNumber - SecondNumber
    ' etc

当你忘记它是“添加”，“添加”，“添加”，“添加”还是“添加”（和/或拼错它“添加”）时，这可以防止令人讨厌的错误。

计算器;显示数字和运算符

1 个答案: