C# 不能隐式转换类型 bool？
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Cannot implicitly convert type bool?
提问by user603007
I am trying to convert my nullable bool value and I am getting this error.
我正在尝试转换我的可为 null 的 bool 值，但出现此错误。
Cannot implicitly convert type 'bool?' to 'bool'. An explicit conversion exists (are you missing a cast?)
For example:
例如：
public virtual bool? MyBool
{
get;
set;
}
if (!MyBool){}
采纳答案by SLaks
As the error states, you can't use a bool?in a conditional. (What would happen if it's null?)
正如错误所述，您不能bool?在条件中使用 a 。（如果是会发生什么null？）
Instead, you can write if (MyBool != true)or if (MyBool == false), depending on whether you want to include null. (and you should add a comment explaining that)
相反，您可以编写if (MyBool != true)或if (MyBool == false)，具体取决于您是否要包含null. （你应该添加一条评论来解释）
回答by NotMe
You have to use MyBool.Value
你必须使用 MyBool.Value
for example:
例如：
if (!MyBool.Value) { }
However, you should test that it does indeed have a value to begin with. This tests that MyBool has a value and it is false.
但是，您应该测试它确实具有开始的价值。这会测试 MyBool 是否有一个值并且它是假的。
if (MyBool.HasValue && !MyBool.Value) { }
Or you might really want the following that runs the code block if it either has not been assigned or has is false.
或者，如果尚未分配或 has 为 false，您可能真的想要运行代码块的以下内容。
if (!MyBool.HasValue || !MyBool.Value) { }
The question really boils down to whether you truly intended to have a nullable boolean variable and, if so, how you want to handle the 3 possible conditions of null, true or false.
问题实际上归结为您是否真的打算拥有一个可为空的布尔变量，如果是，您希望如何处理null, true or false.
回答by The Real Baumann
You need to check if it has a value. What do you want to do if MyBool == null?
您需要检查它是否具有值。如果你想做什么MyBool == null？
if( MyBool.HasValue && !MyBool.Value ) // MyBool is false
if( MyBool.HasValue && MyBool.Value ) // MyBool is true
if( !MyBool.HasValue ) // MyBool is null
