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我遇到了障碍。我只想了解如何为 SelectedIndex 项目分配声明的成本？我觉得我错过了一些明显的东西。

我已经声明了 taco 类型的成本，但我不确定如何将它们分配给ddlTacoTypeVisual Basic 中的 SelectedIndex 项。使用 switch 语句是个好主意吗？理想情况下，当用户选择“Chipotle Chicken”时，输出应显示成本为 8.99。

任何帮助将非常感激。

干杯，

理查德

输出截图

' Project:  Street Tacos Order Form
' Author:   Richard Lew
' Date:     November 3, 2019
' Purpose:  The web application allows a customer to fill out a street taco order form.

Public Class About
    Inherits Page
    Private _decChicken As Decimal = 8.99
    Private _decPork As Decimal = 9.99
    Private _strFish As Decimal = 12.99
    Private _strBeef As Decimal = 13.99
    Private _strExtra As Decimal = 0.99
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load

    End Sub

    Protected Sub btnSubmit_Click(sender As Object, e As EventArgs) Handles btnSubmit.Click
        ' The btnSubmit click event will calculate the cost of the street tacos
        ' based on the type of tacos selected.

        ' Declare and initialize variables
        Dim decTacoCost As Decimal
        Dim decFinalCost As Decimal
        Dim decTotalCost As Decimal
        Dim decChickenCost As Decimal = 8.99D
        Dim decPorkCost As Decimal = 9.99D
        Dim decFishCost As Decimal = 12.99D
        Dim decBeefCost As Decimal = 13.99D
        Dim decExtraCost As Decimal = 0.99
        Dim strName As String
        Dim strAddress As String
        Dim strPhone As String
        Dim decOrderCost As Decimal = 0D
        Dim strMessage As String

        ' Trim additional spaces that are entered by the user
        strName = txtName.Text.Trim
        strAddress = txtAddress.Text.Trim
        strPhone = txtPhone.Text.Trim

        ' Clear the Order Message
        lblOrder.Text = ""

        ' Ensure a Taco Selection is Selected
        If ddlTacoType.SelectedIndex < 0 Then
            lblTacoTypeError.Visible = True
        Else
            lblTacoTypeError.Visible = False
        End If
        ' Ensure a Topping is Selected
        If Not (chkRedChili.Checked Or chkGreenChili.Checked Or chkBeans.Checked Or chkCream.Checked Or chkLime.Checked Or chkNoToppings.Checked) Then
            lblToppingsError.Visible = True
        Else
            lblToppingsError.Visible = False
        End If

        ' Calculate the cost of the Taco(s) selected by the user
        Select Case decTotalCost
            Case 0
                decTacoCost = decChickenCost
            Case 1
                decTacoCost = decPorkCost
            Case 2
                decTacoCost = decFishCost
            Case 3
                decTacoCost = decBeefCost
            Case 4
                decTacoCost = decExtraCost
        End Select



    End Sub
End Class

当用户在ddlTacoType下拉列表中选择 taco 类型时，程序应将项目与其成本相关联，并在程序结束时计算所选项目的总成本。

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1 回答 1

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您需要在下拉列表的选定索引更改事件中编写逻辑

Protected Sub onSelectedIndexChanged(sender As Object, e As EventArgs) Handles ddlTacoType.SelectedIndexChanged

End Sub
于 2019-11-04T12:20:24.147 回答