该程序应该使用在 Select Case 语句中开头声明的枚举类型。当我运行程序时，无论我选择哪个运算符，它都只使用第一个 case 语句（用于添加）。我尝试在 case 语句中重新排列它们以查看它是否只使用了第一个，但它仍然只是选择了添加。我究竟做错了什么？
Public Class Assignment2Calculator
Dim Operand1 As Decimal
Dim Operand2 As Decimal
Dim CalcOperator As Integer
Enum OperatorEnum
add
divide
multiply
subtract
End Enum
Private Sub Assignment2Calculator_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
cboOperator.DataSource = [Enum].GetValues(GetType(OperatorEnum))
AcceptButton = btnCalculate
End Sub
Private Sub IsValidData(ByVal txtOperand1 As Object, ByVal txtOperand2 As Object)
Operand1 = Convert.ToDecimal(txtOperand1.Text)
Operand2 = Convert.ToDecimal(txtOperand2.Text)
If (Operand1 > 0 Or Operand1 < 1000000) And (Operand2 > 0 Or Operand2 < 1000000) Then
If IsNumeric(Operand1) And IsNumeric(Operand2) Then
End If
Else
MessageBox.Show("Operand 1 or 2 is not valid")
End If
End Sub
Private Sub btnCalculate_Click(sender As System.Object, e As System.EventArgs) Handles btnCalculate.Click
IsValidData(txtOperand1, txtOperand2)
Calculate(Operand1, Operand2, CalcOperator)
End Sub
Private Sub Calculate(ByVal Operand1 As Decimal, ByVal Operand2 As Decimal, _
ByVal CalcOperator As Integer)
'Performs requested operation using select case and enumeration
Dim answer As Decimal
Dim CalcOperatorCase As OperatorEnum
Select Case CalcOperatorCase
Case Is = OperatorEnum.add
answer = Operand1 + Operand2
txtResult.Text = FormatNumber(answer, 3)
Case Is = OperatorEnum.divide
answer = Operand1 - Operand2
txtResult.Text = FormatNumber(answer, 3)
Case Is = OperatorEnum.multiply
answer = Operand1 * Operand2
txtResult.Text = FormatNumber(answer, 3)
Case Is = OperatorEnum.subtract
answer = Operand1 / Operand2
txtResult.Text = FormatNumber(answer, 3)
Case Else
MessageBox.Show("Please select an operator")
End Select
End Sub
End Class