How to Error handling in VB

Question

如何为生成异常处理代码以确保数字输入？我正在为我的visual basic课程做期末考试，有一些错误我想让我的程序变得完美：）。很抱歉他们的标题真的很难制作。我想要它，这样当有人键入字符串而不是整数时，程序就不会关闭。

模块1

Sub Main()
    Dim year, age, again As Integer
retry:
    Console.WriteLine("Enter The year you were born in!")
    Console.WriteLine("")
    year = Console.ReadLine()
    Console.WriteLine("")
    If year < 1894 Or year > 2014 Then GoTo Toyoung
    age = 2014 - year
    Console.WriteLine("You are " & age & " years old")
    Console.WriteLine("")

Answer 1

VB.NET中的异常处理通常是这样工作的。

随着每个过程的开始，你做这个

TRY
''Put some code here
CATCH
''Put code on what to do if it throws an error
FINALLY
''Optional: Any thing that has to be done regardless of wether it throws 
''an exception or not. Usually here is where you would close the connection
END TRY

在您的情况下，您只需要Validate用户输入即可。您需要做的是检查isnumber(nameoftextbox) = False是否给用户一条消息并退出子程序。

Answer 2

一种方法是输入一个字符串，并用isnumeric检查以确保它是数字的，如下所示：

Sub Main()
    Dim year, age, again As Integer
    Dim s as string
retry:
    Console.WriteLine("Enter The year you were born in!")
    Console.WriteLine("")
    s = Console.ReadLine()
    Console.WriteLine("")
    if not isnumeric(s) then goto retry
    year = s
    If year < 1894 Or year > 2014 Then GoTo Toyoung
    age = 2014 - year
    Console.WriteLine("You are " & age & " years old")
    Console.WriteLine("")

另一种方法是使用Try, Catch块。有些人更喜欢它。