Try...Catch...Finally 要检查字符串 VB.Net

Question

我正在尝试根据我之前制作的程序制作一个程序，该程序将平均 10 个数字，并在输入字母时捕获异常。没有检查字母的旧代码是

Module Module1
Sub Main()
    Dim Input As Decimal
    Console.WriteLine("Press the numbers you would like to average and press enter after each number.")
    Console.WriteLine("After the tenth number all the numbers will be averaged together.")
    Input = Console.ReadLine
    Console.WriteLine((Input + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine) / 10)
    Console.ReadKey()
End Sub
End Module

我目前拥有的新程序如下，我遇到了各种各样的问题，因此不胜感激。

Module Module1

Public Sub Main()
    Dim input As Object

    Console.WriteLine("Press the numbers you would like to average and press enter after each number.")
    Console.WriteLine("After the tenth number all the numbers will be averaged together.")
    input = Console.ReadLine
    If Char.IsNumber(Console.ReadLine) Then
        Console.WriteLine((Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine + Console.ReadLine) / 10)
        Console.ReadKey()
    End If
    If Not IsNumeric(Console.ReadLine) Then
        Try
        Catch ex As System.Exception
            System.Console.WriteLine("Please enter a number")
        Finally
            System.Console.WriteLine("Try again without entering any letters")
        End Try
        Console.ReadKey()
    End If



End Sub

End Module

Answer 1

Try/Catch 不能那样工作。该块将执行 Try 和 Catch 之间的任何代码，如果此代码中发生异常，它将转到 Catch-Code。无论如何，最终代码都会在之后执行。你的方法不是很简单。我会建议类似：

Sub Main()
    Console.WriteLine("Please enter ten numbers.")
    Dim nums As New List(Of Double)
    Do
        Dim input As String = Console.ReadLine
        If IsNumeric(input) Then
            nums.Add(CDbl(input))
            Console.WriteLine("Ok. Please enter " & (10 - nums.Count).ToString & " more numbers.")
        ElseIf input = "exit" Then
            Exit Sub
        Else
            Console.WriteLine("Please enter only numeric values. Please try again.")
        End If
    Loop Until nums.Count >= 10
    Dim res As Double = 0
    For i = 0 To nums.Count - 1
        res += nums(i)
    Next
    Console.WriteLine("----------------")
    Console.WriteLine("Average value: " & (res / nums.Count).ToString)
    Console.ReadKey()
End Sub

这不使用 Try/Catch。相反，它检查输入的每一行是否为数字。如果是这样，则将该数字添加到 List(Of Double) 以供以后计算平均值。如果不是数字，将显示一条消息，您必须重试。这一直持续到输入 10 个有效数字。然后计算平均值并显示出来。