Question

我有这行代码来捕获异常，如果输入一个字母，或者它是一个数字，但我已经添加了WHEN以避免捕获数字数据。现在我如何使用异常错误在我的case语句之前使用它以避免运行代码两次，因为一旦案例代码通过它将运行一个已经由try catch处理的清除txtbox，don`如果这对你来说很清楚，但我明白了。这是部分代码......

    Try
        'Integer Levels: intLvls is egual to the assigned text box, the first one from
        'the top, this line of code allow the user input to be captured into a variable.
        intLvls = txtBoxLvl.Text
    Catch ex As Exception When IsNumeric(intLvls)
        ErrTypeLetterFeild1()
    Finally
        analysingvalues1()
    End Try

我想做什么：使用循环直到重新引发异常错误以避免运行以下部分代码：

 Private Sub analysingvalues1()
    Do Until IsNumeric (ex As Exception)<------how do i do this???

    Loop

代码的案例部分：

Select Case intLvls
        'User is prompt with the following label: lblLvl "Level of salespersons 1 - 4"
        'to make a choice from 1 to 4 as available values.
        Case 1 To 4
            'This line regulates the range of acceptable values, first textbox: must be egual
            'or higher than 1 and lower or egual to 4. Upon such rules a validation becomes
            'correct and is directed to the isValidCalculation sub.
            isValidCalculation()
        Case Is < 1
            ErrType1NumberRangeFeild()
        Case Is > 4
            ErrType1NumberRangeFeild()
        Case Else
            If txtBoxLvl.Text = "" Then
                ErrTypeClear1()
            Else
                If Not IsNumeric(txtBoxLvl.Text) Then
                    ErrType1NumberRangeFeild()
                Else
                    ErrTypeLetterFeild1()
                    ErrTypeClear1()
                End If
            End If
    End Select 'Ending choices.
End Sub

请求帮助！

Answer 1

如果启用Option Strict this：

intLvls = txtBoxLvl.Text

将不再编译。这应该告诉你，你做了一些臭的事。

启用Option Strict

正确的解决方案不是盲目地允许运行时为您将字符串转换为int，并捕获异常。

当您将字符串用户输入转换为整数时，错误的输入不是一种异常情况，这是您应该期待的并且是防御性的代码。

我会把它重写成这样的东西：

    'Integer Levels: intLvls is egual to the assigned text box, the first one from
    'the top, this line of code allow the user input to be captured into a variable.

    if integer.TryParse( txtBoxLvl.Text, intLvls )
        analysingvalues1()
    else
        ErrTypeLetterFeild1()

编辑 - 正如Chris下面指出的，我的意思是Option Strict。我建议使用但是显式和严格，如果可用则推断。

如何使用Do Until与之前的Try Catch Exception一起避免运行代码两次

1 个答案: