解析字符串到整数（不惜任何代价水） [英] Parse String to Integer (come hell or high water)

问题描述

我需要保持传统VB.NET Web应用程序。数据类型是，我会说，不一致的。尤其是还有就是有时存储为整数，有时为字符串数据，我必须可靠地解析字符串为整数。如果解析出了问题，应该始终返回0。

I need to maintain a legacy VB.NET web application. Data typing is, I would say, inconsistent. Especially, there are data that is stored sometimes as integers and sometimes as strings, and I have to parse strings to integers reliably. If parsing goes wrong it should always return 0.

问题是，我不能使用任何的.NET / VB.NET解析功能，但我不得不依靠自制的功能。

The problem is, I can't use any of the .NET/VB.NET parsing functions for this, but I have to rely on a self-made function.

我可以用一个班轮标准框架调用做好每串到整数解析任务？

Could I use a one-liner standard framework call to do every String-to-Integer parsing task?

让我们说有一个可以为空，空字符串，包含像10重presentation整数或含有别的东西。

Let's say there is a string that can be null, empty, contain an integer representation like "10" or contain something else.

我曾与一个空，输入字符串尝试这些

CType(string, Integer) -> Conversion from string "" to type 'Integer' is not valid.
Convert.ToInt32(string) -> Input string was not in a correct format.
Integer.Parse(string) -> Input string was not in a correct format.
CInt(string) -> Conversion from string "" to type 'Integer' is not valid.
Val(string) -> Success!

但即使瓦尔可能会失败。该万无一失的方法是调用一个自制的功能：

But even Val can fail. The surefire way is to call a self-made function:

   Public Function ToInteger(ByVal s As String) As Integer

        s = Trim(s)
        Dim i As Integer

        Try
            i = Val(s)
        Catch ex As Exception
            i = 0
        End Try

        Return i

    End Function

我觉得这很烂。这是不好的，因为：

I think this sucks. This is bad because:

• 我试图解析字符串为整数！这不是火箭科学，即使语义参与


• 自制标准不沾得非常好。某处在code，你总能找到打破标准框架的解决方案

其结果是有在软件不必要的错误。我指责标准框架这一点。除非，当然更好的解决方案被发现：）

As a result there are unnecessary bugs in the software. And I accuse the standard framework for this. Unless, of course a better solution is found :)

感谢所有的答案。 Int32.TryParse是完美的在这里。

Thanks for all the answers. Int32.TryParse is perfect here.

但是，如果你要输入的第一个转换为字符串，中投可能会失败。一个可能的DBNull值从数据库中读取对象时一样。

But if you have to cast the input to a string first, the cast can fail. Like when reading from a database object with a possible DBNull value.

推荐答案

使用<一个href=\"http://msdn.microsoft.com/en-us/library/system.int32.tryparse.aspx\"><$c$c>Int32.TryParse而忽略了返回值 - 只使用了参数在的值。你所要做的，虽然修剪自己。

Use Int32.TryParse and ignore the return value - just use the value in the out parameter. You'll have to do the trimming yourself though.

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