不能将 int 转换为 bool [英] Can't cast int to bool

问题描述

我面临的问题是，在我的情况下，C# 无法将数字 1 转换为 bool.在我的场景中 (bool)intValue 不起作用.我收到一个 InvalidCastException.我知道我可以使用 Convert.ToBoolean(...) 但我只是想知道它不起作用.对此有什么解释吗?

I'm facing the problem that C# in my case can't cast the number 1 to bool. In my scenario (bool)intValue doesn't work. I get an InvalidCastException. I know I can use Convert.ToBoolean(...) but I'm just wondering it doesn't work. Any explanation for this?

我的代码是

if (actualValueType.Name == "Boolean" || setValueType.Name == "Boolean")
{
   if ((bool)actualValue != (bool)setValue)
   ...
}

推荐答案

int 和 bool 不能隐式转换(例如，与 C++ 相反).

int and bool can't be converted implicitly (in contrast to C++, for example).

这是一个语言设计者做出的明智决定，目的是在条件中使用数字时避免代码出错.条件需要显式地采用 boolean 值.

It was a concious decision made by language designers in order to save code from errors when a number was used in a condition. Conditions need to take a boolean value explicitly.

不能写:

int foo = 10;

if(foo) {
  // Do something
}

想象一下，如果开发者想将 foo 与 20 进行比较，但错过了一个等号:

Imagine if the developer wanted to compare foo with 20 but missed one equality sign:

if(foo = 20) {
  // Do something
}

上面的代码可以编译并运行 - 并且副作用可能不是很明显.

The above code will compile and work - and the side-effects may not be very obvious.

对switch 进行了类似的改进:您不能从一种情况跌落到另一种情况 - 您需要明确的 break 或 return.

Similar improvements were done to switch: you cannot fall from one case to the other - you need an explicit break or return.

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