Question

我正在使用在线教程教自己VBA。使用我到目前为止学到的东西，我制作了一个简单的BODMAS问题生成器。但是，我无法弄清楚如何计算生成的问题的答案。这就是我所做的：

Dim Indicator As String, Equation As String, IndicatorNum As Integer, RandNum As Integer, Answer As Integer

Type EqnStatements
   Statement1 As Integer
   Statement2 As Integer
   Statement3 As Integer
End Type

Type Indicators
   Indicator1 As String
   Indicator2 As String
End Type

Private Sub IndicatorGenerator()
    IndicatorNum = Int(Rnd * 4)
    Select Case IndicatorNum
    Case Is = 0
        Indicator = "+"
    Case Is = 1
        Indicator = "-"
    Case Is = 2
        Indicator = "*"
    Case Is = 3
        Indicator = "/"
End Select
End Sub

Private Sub StatementGenerator()
RandNum = Int(Rnd * 10 + 1)
End Sub

Sub EquationGenerate()
Dim Eqn As EqnStatements, Ind As Indicators

    StatementGenerator
        Eqn.Statement1 = RandNum
    StatementGenerator
        Eqn.Statement2 = RandNum
    StatementGenerator
        Eqn.Statement3 = RandNum

    IndicatorGenerator
        Ind.Indicator1 = Indicator
    IndicatorGenerator
        Ind.Indicator2 = Indicator

    Equation = Eqn.Statement1 & " " & Ind.Indicator1 & " " & Eqn.Statement2 & " " & Ind.Indicator2 & " " & Eqn.Statement3

    Cells(2, 3) = Equation
    End Sub


Sub AnswerShow()

  Answer = Eqn.Statement1 & Ind.Indicator1 & Eqn.Statement2 & Ind.Indicator2 & Eqn.Statement3
  Cells(3, 3) = Answer

End Sub

第一个主要Sub工作正常，并产生输出。当我运行第二个主子（AnswerShow）时，我收到一个错误：“需要对象”。我不知道如何使用存储在变量中的值来计算方程式。

Answer 1

您需要面对＆＃39;对象的原因＆＃39;错误，是您尝试在Eqn过程中使用变量AnswerShow，但此变量不存在。

您在Eqn过程中为对象变量EquationGenerate的属性指定了值，但是在此过程完成运行后，此对象已从内存中丢失。

您必须将Eqn对象变量传递到AnswerShow过程才能访问属性。

我还建议使用函数生成数字，而不是使用公共变量的过程。见下面的代码。

Private Function Indicator() As String

    Dim indicator_num As Integer

    indicator_num = Int(Rnd * 4)
    Select Case indicator_num
        Case 0
            Indicator = "+"
        Case 1
            Indicator = "-"
        Case 2
            Indicator = "*"
        Case 3
            Indicator = "/"
    End Select

End Function

Private Function RandNum() As Integer

    RandNum = Int(Rnd * 10 + 1)

End Function

Sub EquationGenerate()

    Dim Eqn As EqnStatements, Ind As Indicators

    Eqn.Statement1 = RandNum
    Eqn.Statement2 = RandNum
    Eqn.Statement3 = RandNum

    Ind.Indicator1 = Indicator
    Ind.Indicator2 = Indicator

    Equation = Eqn.Statement1 & " " & Ind.Indicator1 & " " & Eqn.Statement2 & " " & Ind.Indicator2 & " " & Eqn.Statement3

    Cells(2, 3) = Equation

    AnswerShow Eqn, Ind

End Sub


Sub AnswerShow(ByRef Eqn As EqnStatements, ByRef Ind As Indicators)

    Answer = Eqn.Statement1 & Ind.Indicator1 & Eqn.Statement2 & Ind.Indicator2 & Eqn.Statement3
    Cells(3, 3) = Answer

End Sub

Answer 2

您将字符'*'，'/'，'+'和' - '存储在名为“Indicator”的内存位置。然而，这并不能使它们成为指标的功能。

从理论上讲，您需要编写解释每个字符的代码，然后命令进行适当的计算：

`If Ind = "*" then Ans = x * y

在你的情况下，有一些额外的编码可以使序列正确。

VBA有一个评估函数（https://msdn.microsoft.com/en-us/library/office/ff193019.aspx），它将评估一个字符串公式。因此，您只需将AnswerShow行更改为

即可

Answer = Evaluate(Eqn.Statement1 & Ind.Indicator1 & Eqn.Statement2 & Ind.Indicator2 & Eqn.Statement3)

学习VBA - BODMAS生成器

2 个答案: