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http://duckula.blogbus.com/logs/209912.html

Private Sub Command1_Click()

    If TxtNum1.Text = "" Then
        MsgBox "请输入数字！", vbExclamation + vbOKOnly
        Else
            If (Val(TxtNum1.Text) < 1) Or (Val(TxtNum1.Text) >= 10) Then
                MsgBox "请输入一个1－10的数！", vbExclamation + vbOKOnly
                    Else
                        Num(1) = Val(TxtNum1.Text)
            End If
    End If
   
    If TxtNum2.Text = "" Then
        MsgBox "请输入数字！", vbExclamation + vbOKOnly
        Else
            If (Val(TxtNum2.Text) < 1) Or (Val(TxtNum2.Text) >= 10) Then
                MsgBox "请输入一个1－10的数！", vbExclamation + vbOKOnly
                    Else
                        Num(2) = Val(TxtNum2.Text)
            End If
    End If
   
    If TxtNum3.Text = "" Then
        MsgBox "请输入数字！", vbExclamation + vbOKOnly
        Else
            If (Val(TxtNum3.Text) < 1) Or (Val(TxtNum3.Text) >= 10) Then
                MsgBox "请输入一个1－10的数！", vbExclamation + vbOKOnly
                    Else
                        Num(3) = Val(TxtNum3.Text)
            End If
    End If
   
    If TxtNum4.Text = "" Then
        MsgBox "请输入数字！", vbExclamation + vbOKOnly
        Else
            If (Val(TxtNum4.Text) < 1) Or (Val(TxtNum4.Text) >= 10) Then
                MsgBox "请输入一个1－10的数！", vbExclamation + vbOKOnly
                    Else
                        Num(4) = Val(TxtNum4.Text)
            End If
    End If
   
    a = OperatorModule.Operator()
   
    If Not (OperateorString1 = "") Then
        Print OperateorString1
    End If
   
    If Not (OperateorString2 = "") Then
        Print OperateorString2
    End If
   
    If Not (OperateorString3 = "") Then
        Print OperateorString3
    End If
   
    If Not (OperateorString4 = "") Then
        Print OperateorString4
    End If
   
    If Not (OperateorString5 = "") Then
        Print OperateorString5
    End If
   
End Sub

－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－
'模块OperatorModule

Public Num(4) As Single             '定义数组，存储输入的数字

Public OperateorString1 As String       '运算表达式
Public OperateorString2 As String
Public OperateorString3 As String
Public OperateorString4 As String
Public OperateorString5 As String

Function Operator() As Integer

    Dim a As Integer        '定义数字数组下彪，用来产生数字组合
    Dim b As Integer
    Dim c As Integer
    Dim d As Integer
   
    Dim op1 As Integer      '定义运算付数组下标，用来产生运算符组合
    Dim op2 As Integer
    Dim op3 As Integer

    Dim answer1 As Single   '存储运算结果
    Dim answer2 As Single
    Dim answer3 As Single

    Dim BracketLeft1 As String, BracketRight1 As String, BracketLeft2 As String, BracketRight2 As String    '括号，分别表示为：第一个左括号，第一个右括号，第二个左括号，第二个右括号

    For a = 1 To 4                                          '产生4个数字的组合，一共有4!=24种组合
        For b = 1 To 4
            If b <> a Then
                For c = 1 To 4
                    If (c <> a) And (c <> b) Then
                        For d = 1 To 4
                            If (d <> a) And (d <> b) And (d <> c) Then
                               
                                For op1 = 1 To 4        '运算符排序 共有4*4*4=64种
                                    For op2 = 1 To 4
                                        For op3 = 1 To 4

                                           
                                            If caculate(Num(a), Num(b), op1, answer1) And caculate(answer1, Num(c), op2, answer2) And caculate(answer2, Num(d), op3, answer3) Then
                                                If answer3 = 24 Then        '如果结果为24，则产生运算表达式
                                                    '先将四个括号都清空
                                                    BracketLeft1 = ""
                                                    BracketRight1 = ""
                                                    BracketLeft2 = ""
                                                    BracketRight2 = ""
                                                    '如果第一个运算符为+或- 且第二个运算为 *或/ 那么第二个括号不能少
                                                    If (operate(op1) = "+" Or operate(op1) = "-") And (operate(op2) = "*" Or operate(op2) = "/") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If
                                                    '如果第二个运算符为+或- 且第三个运算为 *或/ 那么第一个括号不能少
                                                    If (operate(op2) = "+" Or operate(op2) = "-") And (operate(op3) = "*" Or operate(op3) = "/") Then
                                                        BracketLeft1 = "("
                                                        BracketRight1 = ")"
                                                    End If

                                                    OperateorString1 = BracketLeft1 + BracketLeft2 + Trim(Str$(Num(a))) + Trim(operate(op1)) + Trim(Str$(Num(b))) + BracketRight2 + Trim(operate(op2)) + Trim(Str$(Num(c))) + BracketRight1 + Trim(operate(op3)) + Trim(Str$(Num(d))) '返回((x@y)@z)@w 格式的表达式，但此时这两个括号未必都还在
                                                    Operator = answer3
                                                   
                                                End If
                                            End If

                                            If caculate(Num(a), Num(b), op1, answer1) And caculate(Num(c), Num(d), op3, answer2) And caculate(answer1, answer2, op2, answer3) Then
                                                If answer3 = 24 Then
                                                    BracketLeft1 = ""
                                                    BracketRight1 = ""
                                                    BracketLeft2 = ""
                                                    BracketRight2 = ""
                                                   
                                                    If (operate(op1) = "+" Or operate(op1) = "-") And (operate(op2) = "*" Or operate(op2) = "/") Then
                                                        BracketLeft1 = "("
                                                        BracketRight1 = ")"
                                                    End If
                                                  
                                                    If (operate(op3) = "+" Or operate(op3) = "-") And (operate(op2) = "*" Or operate(op2) = "/") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If
                                                   
                                                    If (operate(op2) = "-") And (operate(op3) = "+" Or operate(op3) = "-") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If

                                                    OperateorString2 = BracketLeft1 + Trim(Str$(Num(a))) + Trim(operate(op1)) + Trim(Str$(Num(b))) + BracketRight1 + Trim(operate(op2)) + BracketLeft2 + Trim(Str$(Num(c))) + Trim(operate(op3)) + Trim(Str$(Num(d))) + BracketRight2 '返回表达式
                                                    Operator = answer3
                                                   
                                                End If
                                            End If

                                            If caculate(Num(b), Num(c), op2, answer1) And caculate(Num(a), answer1, op1, answer2) And caculate(answer2, Num(d), op3, answer3) Then
                                                If answer3 = 24 Then
                                                    BracketLeft1 = ""
                                                    BracketRight1 = ""
                                                    BracketLeft2 = ""
                                                    BracketRight2 = ""
                                                   
                                                    If (operate(op1) = "/") Or (operate(op1) = "*" And (operate(op2) = "+" Or operate(op2) = "-")) Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If

                                                    If (operate(op1) = "-") And (operate(op2) = "+" Or operate(op2) = "-") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If

                                                   
                                                    If (operate(op1) = "+" Or operate(op1) = "-") And (operate(op3) = "*" Or operate(op3) = "/") Then
                                                        BracketLeft1 = "("
                                                        BracketRight1 = ")"
                                                    End If

                                                    OperateorString5 = BracketLeft1 + Trim(Str$(Num(a))) + Trim(operate(op1)) + BracketLeft2 + Trim(Str$(Num(b))) + Trim(operate(op2)) + Trim(Str$(Num(c))) + BracketRight2 + BracketRight1 + Trim(operate(op3)) + Trim(Str$(Num(d)))
                                                    Operator = answer3
                                                   
                                                End If
                                            End If

                                          
                                            If caculate(Num(b), Num(c), op2, answer1) And caculate(answer1, Num(d), op3, answer2) And caculate(Num(a), answer2, op1, answer3) Then
                                                If answer3 = 24 Then
                                                    BracketLeft1 = ""
                                                    BracketRight1 = ""
                                                    BracketLeft2 = ""
                                                    BracketRight2 = ""
                                                 
                                                    If (operate(op2) = "+" Or operate(op2) = "-") And (operate(op3) = "*" Or operate(op3) = "/") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If
                                                   
                                                    If (operate(op1) = "/") Or (operate(op1) = "*" And (operate(op3) = "+" Or operate(op3) = "-")) Then
                                                        BracketLeft1 = "("
                                                        BracketRight1 = ")"
                                                    End If
                                                  
                                                    If (operate(op1) = "-") And (operate(op3) = "+" Or operate(op3) = "-") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If

                                                    OperateorString3 = Trim(Str$(Num(a))) + Trim(operate(op1)) + BracketLeft1 + BracketLeft2 + Trim(Str$(Num(b))) + Trim(operate(op2)) + Trim(Str$(Num(c))) + BracketRight2 + Trim(operate(op3)) + Trim(Str$(Num(d))) + BracketRight1
                                                    Operator = answer3
                                                   
                                                End If
                                            End If

                                            If caculate(Num(c), Num(d), op3, answer1) And caculate(Num(b), answer1, op2, answer2) And caculate(Num(a), answer2, op1, answer3) Then
                                                If answer3 = 24 Then
                                                    BracketLeft1 = ""
                                                    BracketRight1 = ""
                                                    BracketLeft2 = ""
                                                    BracketRight2 = ""
                                                   
                                                    If (operate(op1) = "/") Or (operate(op1) = "*" And (operate(op2) = "+" Or operate(op2) = "-")) Then
                                                        BracketLeft1 = "("
                                                        BracketRight1 = ")"
                                                    End If

                                                  
                                                    If (operate(op1) = "-") And (operate(op2) <> "*" Or operate(op2) <> "/") Then
                                                        BracketLeft1 = "("
                                                        BracketRight1 = ")"
                                                    End If
                                                 
                                                    If (operate(op2) = "/") Or (operate(op2) = "*" And (operate(op3) = "+" Or operate(op3) = "-")) Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If

                                                  
                                                    If (operate(op2) = "-") And (operate(op3) = "+" Or operate(op3) = "-") Then
                                                        BracketLeft2 = "("
                                                        BracketRight2 = ")"
                                                    End If
                                                    OperateorString4 = Trim(Str$(Num(a))) + Trim(operate(op1)) + BracketLeft1 + Trim(Str$(Num(b))) + Trim(operate(op2)) + BracketLeft2 + Trim(Str$(Num(c))) + Trim(operate(op3)) + Trim(Str$(Num(d))) + BracketRight2 + BracketRight1
                                                    Operator = answer3
                                                   
                                                End If
                                            End If

                                        Next op3
                                    Next op2
                                Next op1
                            End If
                        Next d
                    End If
                Next c
            End If
        Next b
    Next a
    Operator = answer3
End Function
'计算结果
Function caculate(X As Single, Y As Single, Operator As Integer, answer As Single) As Boolean
    Select Case Operator
        Case 1
            On Error GoTo ErrDoing
            answer = X + Y
        Case 2
            On Error GoTo ErrDoing
            answer = X - Y
        Case 3
            On Error GoTo ErrDoing
            answer = X * Y
        Case 4
            On Error GoTo ErrDoing
            If Y = 0 Then  '被除数不能为0
                caculate = False
                Exit Function
            Else
                answer = X / Y
            End If
    End Select
ErrDoing:
    If Err.Number = 6 Then
        caculate = False
    End If
    caculate = True
End Function
'返回运算符
Function operate(op As Integer) As String
    Select Case op
        Case 1
            operate = "+"
        Case 2
            operate = "-"
        Case 3
            operate = "*"
        Case 4
            operate = "/"
    End Select
End Function