Question

我是VB的新手，对于一个班级项目，我们要制作一个改变计算器，类似于之前提出的问题。我有欠款和金额标签和文本框。如果拥有的金额大于支付的金额，程序应显示消息以提醒客户并告诉他们还要支付多少钱。

我想出来了，但消息中显示的仍然是的数量是-1。

实施例：欠款额：25 支付金额：10 该消息将显示，支付的金额少于欠款。请多支付-1美元。

我不确定我做错了什么，而且我被卡住了。任何帮助将不胜感激！

Option Strict On
Option Explicit On

Public Class Form1
Dim AmountPaid As Double
Dim AmountOwed As Double


Private Sub CalculateButton_Click(sender As Object, e As EventArgs) Handles       CalculateButton.Click
    'input amount owed from OwedMaskedTextBox
    'input paid amount from PaidTextBox
    AmountOwed = Convert.ToDouble(OwedTextBox.Text)
    AmountPaid = Convert.ToDouble(PaidTextBox.Text)


    'calculate difference of amount owed and paid
    'display an alert message if paid amount is less than what is owed
    Dim dif As Double
    Dim result As Double = 0

    result = CDbl(AmountPaid < AmountOwed)


    dif = AmountPaid - AmountOwed
    If CBool(result) Then
        AlertLabel.Text = "Amount paid is less than what is owed." &
            "Please pay $ " & result & "  more."

    Else
        AlertLabel.Text = ""
    End If

    'display the result
    'let totallabel change text to display the difference
    TotalLabel.Text = "Change: " &
        dif.ToString()

End Sub
End Class

Answer 1

以这种方式更改代码

'calculate difference of amount owed and paid
'display an alert message if paid amount is less than what is owed
Dim result As Boolean

result = (AmountPaid < AmountOwed)
dif = AmountPaid - AmountOwed
If result Then
  .....

表达式(AmountPaid < AmountOwed)是一个布尔表达式，您可以直接赋值给布尔变量。然后你可以在显示你的消息之前测试这个布尔值。

因此，不需要这些转换会引入错误。

在改变计算器，VB VS2012上显示“支付金额”是不够的

1 个答案: