vb 制作简易计算器

功能要求：

1、  能进行加减乘除4种运算

2、  可以清除运行结果

3、  输错的数字可以退格改正

追问：写一下  做这题的感受 遇到什么问题 什么的  谢谢  老师留得作业

答案：初学者的VB计算器

窗体代码如下

Option Explicit

Dim blnStratrOperationFlag As Boolean   '是否开始运算
Dim lngOperationFlag As Long            '运算标志
Dim dblFirstOperationValue As Double    '先前的操作数

Private Sub cmdValuedDecimal_Click(Index As Integer) '数字及小数点

    Select Case Index

        Case 0

        AddTextOperationValue "0"

        Case 1

        AddTextOperationValue "1"

        Case 2

        AddTextOperationValue "2"

        Case 3

        AddTextOperationValue "3"

        Case 4

        AddTextOperationValue "4"

        Case 5

        AddTextOperationValue "5"

        Case 6

        AddTextOperationValue "6"

        Case 7

        AddTextOperationValue "7"

        Case 8

        AddTextOperationValue "8"

        Case 9

        AddTextOperationValue "9"

        Case 10

        AddTextOperationValue "."

    End Select

End Sub

Private Sub AddTextOperationValue(strOperationValue As String)

    If Len(txtOperationValue) > 8 And blnStratrOperationFlag = False Then Exit Sub '判断是否输入数字超过9个

    If txtOperationValue = "0" And strOperationValue = "0" Then Exit Sub           '是否什么也没输入或为0时候输入0则退出

    If lngOperationFlag <> 0 And blnStratrOperationFlag = True Then                '如果有操作符且开始运算为真则

        txtOperationValue = ""
        blnStratrOperationFlag = False

    End If

    If txtOperationValue = "0" And strOperationValue <> "." Then txtOperationValue = "" '头次输入数字

    If Right$(txtOperationValue, 1) = "." And strOperationValue = "." Then Exit Sub     '避免多次输入小数点

    txtOperationValue = txtOperationValue & strOperationValue        '累加字符

End Sub

Private Sub cmdOperation_Click(Index As Integer)  '+ - * / =

    Select Case Index

        Case 0

        lngOperationFlag = 1

        Evaluate

        Case 1

        lngOperationFlag = 2

        Evaluate

        Case 2

        lngOperationFlag = 3

        Evaluate

        Case 3

        lngOperationFlag = 4

        Evaluate

        Case 4

        DisposeResult

    End Select

End Sub

Private Sub Evaluate()      '四则运算赋值

    dblFirstOperationValue = Val(txtOperationValue)

    blnStratrOperationFlag = True
    txtOperationValue = ""

End Sub

Private Sub DisposeResult()  '处理计算结果

    On Error GoTo ToExit     '打开错误陷阱

    Select Case lngOperationFlag  '操作标志

        Case 1

        txtOperationValue = dblFirstOperationValue + Val(txtOperationValue)

        Case 2

        txtOperationValue = dblFirstOperationValue - Val(txtOperationValue)

        Case 3

        txtOperationValue = dblFirstOperationValue * Val(txtOperationValue)

        Case 4

        txtOperationValue = dblFirstOperationValue / Val(txtOperationValue)

    End Select

    lngOperationFlag = 0     '操作标志清0

    Exit Sub

ToExit:

    MsgBox "除数不能为0！", vbOKOnly, "错误"

    Resume Next

End Sub

Private Sub cmdClearAll_Click()        'C按钮清除所有的运算结果

    lngOperationFlag = 0
    txtOperationValue = "0"

End Sub

Private Sub cmdClearLastInput_Click()  'CE按钮清除最后一次输入的数字

    txtOperationValue = "0"

End Sub

Private Sub Form_Unload(Cancel As Integer)

    Set frmCalculator = Nothing

End Sub

其他：这里有篇源码参考
http://wenku.zhaoxi.net/view/b46311c52cc58bd63186bd0f.html 关键你是得先熟悉计算器的计算过程
这要完全做好可不是个简单的事，你参考一下我以前做的一个例子。如果要源代码的话给我邮箱，我把这个例子发给你！

设计时使用了控件数组 cmdnum 0-9 数字
cmdCaculate 0-3 表示+-*/

还用数组记录运算数据，考虑了括号 
布局是在form_load()
 中进行的，如果在窗体中做好了，可以考虑不要部分代码
下面是代码


Private number() As Double, i As Integer
Private strcalculate() As String

Private Sub CALCULATE(strFuhao As String)
If strFuhao = "=" And strcalculate(0, i) = "" Then Exit Sub
Select Case strFuhao '判断当前是什么运算符
Case "+" '刚输入+   ***************************************************************************************************
   strcalculate(1, i) = strFuhao
   Select Case strcalculate(0, i) '判断前面是什么运算
   Case "+"
     number(0, i) = number(0, i) + Val(txtshow.Text)
      txtshow.Text = number(0, i)

   Case "-"
     number(0, i) = number(0, i) - Val(txtshow.Text)
      txtshow.Text = number(0, i)

   Case "*"
     number(0, i) = number(0, i) * Val(txtshow.Text)
     Select Case strcalculate(2, i) '判断乘除法前面有没有加减法要计算,有计算
     Case "+"
        number(0, i) = number(1, i) + number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     Case "-"
        number(0, i) = number(1, i) - number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     End Select
     txtshow.Text = number(0, i)

  Case "/"
     number(0, i) = number(0, i) / Val(txtshow.Text)
     Select Case strcalculate(2, i) '判断乘除法前面有没有加减法要计算,有计算
     Case "+"
        number(0, i) = number(1, i) + number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     Case "-"
        number(0, i) = number(1, i) - number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     End Select
     txtshow.Text = number(0, i)

  Case Else
     number(0, i) = txtshow.Text

  End Select
Case "-" '刚输入-              *******************************************************************************************
   strcalculate(1, i) = strFuhao
   Select Case strcalculate(0, i) '判断前面是什么运算
   Case "+"
     number(0, i) = number(0, i) + Val(txtshow.Text)
           txtshow.Text = number(0, i)

   Case "-"
     number(0, i) = number(0, i) - Val(txtshow.Text)
           txtshow.Text = number(0, i)

   Case "*"
     number(0, i) = number(0, i) * Val(txtshow.Text)
     Select Case strcalculate(2, i) '判断乘除法前面有没有加减法要计算,有计算
     Case "+"
        number(0, i) = number(1, i) + number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     Case "-"
        number(0, i) = number(1, i) - number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     End Select
           txtshow.Text = number(0, i)

  Case "/"
     number(0, i) = number(0, i) / Val(txtshow.Text)
     Select Case strcalculate(2, i) '判断乘除法前面有没有加减法要计算,有计算
     Case "+"
        number(0, i) = number(1, i) + number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     Case "-"
        number(0, i) = number(1, i) - number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     End Select
           txtshow.Text = number(0, i)

  Case Else
     number(0, i) = txtshow.Text

  End Select
Case "*" '刚输入*      *******************************************************************************************
  strcalculate(1, i) = strFuhao
  Select Case strcalculate(0, i)
  Case "*"
    number(0, i) = number(0, i) * Val(txtshow.Text)
          txtshow.Text = number(0, i)

  Case "/"
    number(0, i) = number(0, i) / Val(txtshow.Text)
          txtshow.Text = number(0, i)

  Case "+", "-"
    number(1, i) = number(0, i)
    number(0, i) = Val(txtshow.Text)
    strcalculate(2, i) = strcalculate(0, i)
  Case Else
     number(0, i) = Val(txtshow.Text)
    
  End Select
  

Case "/" '刚输入/     *******************************************************************************************
  strcalculate(1, i) = strFuhao
  Select Case strcalculate(0, i)
  Case "*"
    number(0, i) = number(0, i) * Val(txtshow.Text)
    txtshow.Text = number(0, i)

  Case "/"
    number(0, i) = number(0, i) / Val(txtshow.Text)
          txtshow.Text = number(0, i)

  Case "+", "-"
    number(1, i) = number(0, i)
    number(0, i) = Val(txtshow.Text)
    strcalculate(2, i) = strcalculate(0, i)
  Case Else
     number(0, i) = txtshow.Text
    
  End Select


Case "(" '刚输入前括号    *******************************************************************************************
   i = i + 1
   ReDim Preserve number(2, i) As Double
   ReDim Preserve strcalculate(2, i) As String
   txtshow.Text = 0
Case ")"   ' 刚输入后括号 *******************************************************************************************
   Select Case strcalculate(0, i)
   Case "+"
     number(0, i) = number(0, i) + Val(txtshow.Text)
      txtshow.Text = number(0, i)
       i = i - 1 '让数组最后一纬减1
       ReDim Preserve number(2, i) As Double
       ReDim Preserve strcalculate(2, i) As String

   Case "-"
     number(0, i) = number(0, i) - Val(txtshow.Text)
       txtshow.Text = number(0, i)
       i = i - 1 '让数组最后一纬减1
       ReDim Preserve number(2, i) As Double
       ReDim Preserve strcalculate(2, i) As String

   Case "*"
     number(0, i) = number(0, i) * Val(txtshow.Text)
     Select Case strcalculate(2, i)
     Case "+"
       number(0, i) = number(1, i) + number(0, i)
       txtshow.Text = number(0, i)
       i = i - 1 '让数组最后一纬减1
       ReDim Preserve number(2, i) As Double
       ReDim Preserve strcalculate(2, i) As String
     Case "-"
       number(0, i) = number(1, i) - number(0, i)
       txtshow.Text = number(0, i)
       i = i - 1 '让数组最后一纬减1
       ReDim Preserve number(2, i) As Double
       ReDim Preserve strcalculate(2, i) As String
     End Select
  Case Else
     MsgBox "括号里没有表达式！", vbSystemModal + vbInformation, "输入有误码"
     Exit Sub
  End Select

Case "="
   Select Case strcalculate(0, i) '判断前面是什么运算
   Case "+"
     number(0, i) = number(0, i) + Val(txtshow.Text)
           txtshow.Text = number(0, i)

   Case "-"
     number(0, i) = number(0, i) - Val(txtshow.Text)
           txtshow.Text = number(0, i)

   Case "*"
     number(0, i) = number(0, i) * Val(txtshow.Text)
     Select Case strcalculate(2, i) '判断乘除法前面有没有加减法要计算,有计算
     Case "+"
        number(0, i) = number(1, i) + number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     Case "-"
        number(0, i) = number(1, i) - number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     End Select
           txtshow.Text = number(0, i)

   Case "/"
     number(0, i) = number(0, i) / Val(txtshow.Text)
     Select Case strcalculate(2, i) '判断乘除法前面有没有加减法要计算,有计算
     Case "+"
        number(0, i) = number(1, i) + number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     Case "-"
        number(0, i) = number(1, i) - number(0, i)
        number(1, i) = 0
        strcalculate(2, i) = ""
     End Select
           txtshow.Text = number(0, i)

   End Select
End Select


strcalculate(0, i) = strcalculate(1, i)

'Case 5
' i = i + 1
' ReDim Preserve number(2, i) As Double
' ReDim Preserve strcalculate(2, i) As Integer
' strcalculate(1, i) = strcalculate(1, i - 1)
' GoTo calc1234


'Case 6




'End Select

'txtshow.Text = number(0, i)
'strcalculate(0, i) = strcalculate(1, i)


End Sub


Private Sub cmdBackspace_Click()
If Len(txtshow.Text) > 1 Then
 txtshow.Text = Left(txtshow.Text, Len(txtshow.Text) - 1)
ElseIf txtshow.Text <> "0" Then
 txtshow.Text = "0"
End If

End Sub

Private Sub cmdC_Click()
  ReDim number(2, 0) As Double
  ReDim strcalculate(2, 0) As String
  txtshow.Text = "0"
  i = 0


End Sub

Private Sub cmdcalculate_Click(Index As Integer)

CALCULATE (cmdcalculate(Index).Caption)

End Sub

Private Sub cmdCE_Click()
txtshow.Text = "0"

End Sub

Private Sub cmdnegative_Click()
txtshow.Text = -Val(txtshow.Text)
number(0, i) = txtshow.Text
End Sub

Private Sub cmdnum_Click(Index As Integer)
  If CStr(number(0, i)) = txtshow.Text Then
     txtshow.Text = "0"
  End If
  If Index = 0 And txtshow.Text = "0" Then
  ElseIf txtshow.Text = "0" Then
      txtshow.Text = Index
  Else
      txtshow.Text = txtshow.Text & Index
  End If
  
End Sub

Private Sub cmdparentheses_Click(Index As Integer)
CALCULATE (cmdparentheses(Index).Caption)
Dim intkuohao As Integer
Dim strkuohao As String
For intkuohao = 1 To i
  strkuohao = strkuohao & " ("
Next intkuohao
Label1.Caption = strkuohao
Label1.Refresh

End Sub

Private Sub cmdpoint_Click()
 If InStr(txtshow.Text, ".") = 0 Then txtshow.Text = txtshow.Text & "."
End Sub



Private Sub cmdResult_Click()
  If i = 0 Then
    For intkuohao = i To 1 Step -1
       CALCULATE (")")
    Next intkuohao
  
  End If
  CALCULATE (cmdResult.Caption)
  ReDim strcalculate(2, 0) As String
  ReDim number(2, 0) As Double
  i = 0
  
End Sub

Private Sub Form_Load()
Dim intwidth As Integer, intheight As Integer
intwidth = cmdnum(0).Width + 50
intheight = cmdnum(0).Height + 50


For i = 1 To 9
  cmdnum(i).Caption = i
  cmdnum(i).Move cmdnum(0).Left + intwidth * ((i - 1) Mod 3), cmdnum(0).Top - intheight * ((i - 1) \ 3) - intheight
Next i
For i = 0 To 3
  cmdcalculate(i).Move cmdnum(9).Left + intwidth, cmdnum(9).Top + intheight * i
Next i
cmdnegative.Move cmdnum(0).Left + intwidth, cmdnum(0).Top
cmdpoint.Move cmdnum(0).Left + intwidth * 2, cmdnum(0).Top
cmdCE.Move cmdnum(0).Left + intwidth * 2, cmdnum(0).Top - 4 * intheight
cmdC.Move cmdnum(0).Left + intwidth * 3, cmdnum(0).Top - 4 * intheight
cmdResult.Move cmdnum(0).Left + intwidth * 4, cmdnum(0).Top - 4 * intheight
cmdBackspace.Move cmdnum(0).Left + intwidth * 4, cmdnum(0).Top - 2 * intheight
For i = 0 To 1
  cmdparentheses(i).Move cmdnum(0).Left + i * intwidth, cmdnum(0).Top - 4 * intheight
Next i

txtshow.Move cmdnum(0).Left, cmdnum(7).Top - 3 * intheight, 5 * intwidth
Label1.Move cmdnum(0).Left, cmdnum(7).Top - 3 * intheight - Label1.Height, 5 * intwidth

txtshow.Text = "0"

i = 0
ReDim strcalculate(2, i) As String
ReDim number(2, i) As Double

End Sub

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