Question

我正在尝试使其能够计算用户在银行帐户余额低于0之前可以进行的提款次数。输入的数字分别为1000、60、50、300、800、53、2009和2015 。应该以1000开头，然后减去60，然后是50，然后是300，然后是800，这将是4次提款。我不这样做，我也不知道我在做什么错。

Private Sub btnBankAccount_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBankAccount.Click
    Dim inFile As StreamReader = New StreamReader("bank1.txt")
    Dim withdrawls As Integer 'count times
    Dim money As Integer 'amount of money
    Dim difference As Integer = 0 'difference caused by the withdrawls


    Do 'read in numbers
        money = Val(inFile.ReadLine())
        'determine the amount of money
        If money > 0 Then
            withdrawls = withdrawls + 1
            difference = difference - money
        End If
    Loop Until difference < 0
    'display results
    Me.lblOutput.Text = withdrawls
End Sub

Answer 1

在我看来，如果您将difference定义为：

Dim difference As Integer = 0

现在，为了帮助您提高编码风格，建议您像这样编写代码：

Private Sub btnBankAccount_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBankAccount.Click
    Me.lblOutput.Text = GetWithdrawlCount(1000, "bank1.txt")
End Sub

Private Function GetWithdrawlCount(ByVal limit As Decimal, ByVal file As String) As Integer

    Dim withdrawls As Integer = 0
    Dim difference As Decimal = limit

    For Each line In System.IO.File.ReadLines(file)
        Dim money = Decimal.Parse(line)
        If money > 0 Then
            withdrawls = withdrawls + 1
            difference = difference - money
        End If
        If difference < 0 Then
            Exit For
        End If
    Next

    Return withdrawls

End Function

我故意将GetWithdrawlCount分隔开，以便没有没有对任何UI元素的引用，并且没有魔术数字或魔术字符串。以这种方式编写代码可以使您的代码更简洁，更易于测试。

计算从银行帐户中提款的次数

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