开机可空布尔：案件进入空当值为true [英] Switch on Nullable Boolean : case goes to null when value is true

问题描述

我认识来处理可空类型的正确方法是使用HasValue属性。不过，我想知道为什么空的情况下，而不是默认以下switch语句休息。使用VS​​2015 C＃4.0。正在使用VS2010 C＃4.0的另一台计算机没有此相同的问题。

I realize the proper way to handle nullable types is to use the HasValue property. But I would like to know why the following switch statement breaks on the null case instead of default. Using VS2015 C#4.0. Another computer that is using VS2010 C#4.0 does not have this same problem.

 private void Testing()
    {
        bool? boolValue = true;

        switch (boolValue)
        {
            case null: 
                break; //even though value is true, code runs here

            default:
                break;
        }
    }

修改：行为与任何可空如果只情况下，空和观察到的默认中指定。

Edit: Behavior is observed with any Nullable if only case Null and default is specified.

推荐答案

这将是一个非常简短的回答：你刚才打的罗斯林BUG＃4701 ，报道两个星期前。

This is going to be a very short answer: You just hit Roslyn bug #4701, reported two weeks ago.

里程碑设置为1.1，所以现在你将有一个单独的如果子句来解决此，而等待下一个编译器的更新。

The milestone is set to 1.1, so right now you'll have to workaround this with a separate if clause, while waiting for the next compiler update.

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