Question

我正在使用asp.net vb，网站在客户端。我不知道如何执行此计算。该网站将设定付款计划。时间范围是12个月，最低付款金额可以是25，但如果他们输入超过25个是好的。 1.如果余额小于25，那么标签会显示他们无法设置pmt计划，但如果我将其更改为余额，则没有任何反应，它仍然显示标签的错误并且没有如果我做对了，我就继续前进吧。 2.如何确保用户遵守指南或他们无法进入祝贺页面？下面是我的代码，但它不起作用，我的逻辑不起作用。有人可以帮我这个。这是默认页面：

    <form id="form1" runat="server">
<div>
Enter balance<br />
    <asp:TextBox ID="Balance" runat="server"></asp:TextBox>
    <br />
    Enter amount to pay<br />
    <asp:TextBox ID="PmtAmount" runat="server" AutoPostBack="True"></asp:TextBox>
    <br />
    <asp:Label runat="server" ID="lblError" Text=""></asp:Label>
    <br />
    <br />
    <asp:Button ID="Button1" runat="server" Text="submit" Width="90px" />
</div>
</form>

代码背后：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    If Page.IsPostBack Then
    End If
End Sub

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    Dim pmt As Decimal
    Dim bal As Decimal
    Dim minpmt As Decimal

    If Not Decimal.TryParse(Balance.Text, bal) OrElse _
       Not Decimal.TryParse(PmtAmount.Text, pmt) Then
        lblError.Visible = True
        lblError.Text = "Balance and Payment Amount must be a decimal"
    Else
        If bal < 25.0 Then
            lblError.Visible = True
            lblError.Text = "You can't set a pymt plan, please pay in full"
        ElseIf pmt < 25.0 Then
            lblError.Visible = True
            lblError.Text = "min is 25.00"
        ElseIf bal > 300.0 Then
            minpmt = bal / 12
            lblError.Visible = True
            lblError.Text = "your min pmt is " & Math.Round(minpmt, 2)
        ElseIf pmt > (bal / 12) Then
            Response.Redirect("default2.aspx")
        End If
    End If

Answer 1

以下伪代码应该有助于您朝着正确的方向前进：

if balance is less than 25 then
    show label with text "You can't set a payment plan"
else if payment is less then 25 then
    show label with text "Minimum payment is 25"
else if paymentamount > balance / 12 then
    redirect to page 2

此外，pmt = Balance.Text / TF之类的操作危险 - 如果Balance.Text不是数字，则会出现异常。

我建议在Balance.Text和PmtAmount.Text上使用Decimal.TryParse将文本转换为小数（如果转换失败，则显示错误）。

修改

If Decimal.TryParse(Balance.Text, bal) < 25.0 Then不是使用Decimal.TryParse的正确方法。

Decimal.TryParse返回一个布尔值并将转换结果存储在out参数中，因此您需要执行以下操作：

Dim bal As Decimal If Not Decimal.TryParse(Balance.Text, bal) Then ' Set the error label letting the user know to enter a number End If

如果转化成功，bal将获得转化结果，您可以稍后在代码中使用。

您可以将上面的伪代码修改为以下内容：

if balance is not a number or payment amount is not a number show label with text "balance and payment amount must be a decimal value" else if balance is less than 25 then show label with text "You can't set a payment plan" else if payment is less then 25 then show label with text "Minimum payment is 25" else if paymentamount > balance / 12 then redirect to page 2

简而言之，在余额和付款金额上使用Decimal.TryParse - 如果其中任何一个失败，请显示错误消息。

否则（else）使用out变量中包含的转换值进行剩余的验证。

<强>代码

你走在正确的轨道上 - 你的最终代码看起来像这样：

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click Dim TF As Decimal = 12 'TimeFrame Dim Min As Decimal = 25 'Minimum payment plan amount Dim pmt As Decimal Dim bal As Decimal If Not Decimal.TryParse(Balance.Text, bal) OrElse _ Not Decimal.TryParse(PmtAmount.Text, pmt) Then lblError.Visible = True lblError.Text = "Balance and Payment Amount must be a decimal" Else If bal < 25.0 Then lblError.Visible = True lblError.Text = "You can't set a pymt plan, please pay in full" ElseIf pmt < 25.0 Then lblError.Visible = True lblError.Text = "min is 25.00" ElseIf pmt > (bal / 12) Then Response.Redirect("default2.aspx") End If End If End Sub

有人可以帮我解释这个计算的逻辑吗？

1 个答案: