为什么“int []是uint [] == true”在C＃

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问题描述

有人可以澄清C＃是关键字。特别是这两个问题：

Can somebody clarify the C# is keyword please. In particular these 2 questions:

Q1）第5行;为什么这会返回true？

Q1) line 5; Why does this return true?

Q2）line 7;为什么没有转义异常？

Q2) line 7; Why no cast exception?

public void Test()
{
    object intArray = new int[] { -100, -200 };

    if (intArray is uint[]) //why does this return true?
    {
        uint[] uintArray = (uint[])intArray; //why no class cast exception?

        for (int x = 0; x < uintArray.Length; x++)
        {
            Console.Out.WriteLine(uintArray[x]);
        }
    }
}

MSDN的说明情况。它表示是将返回true，如果满足这些条件之一。（http://msdn.microsoft.com/en-us/library/scekt9xw(VS.71).aspx>MDSN文章）

MSDN's description does not clarify the situation. It states that is will return true if either of these conditions are met. (http://msdn.microsoft.com/en-us/library/scekt9xw(VS.71).aspx>MDSN Article)


expression is not null.
expression can be cast to type.

我不相信你可以做一个有效的int []到uint []。因为：

I don't believe that you can do a valid cast of int[] into uint[]. Because:

A）此代码不编译：

int[] signed = new int[] { -100 };
uint[] unsigned = (uint[])signed;

B）在调试器中执行转换会产生错误：

B) Doing the cast in the debugger gives an error:

(uint[])signed
"Cannot convert type 'int[]' to 'uint[]'"

没错，如果第3行是int []而不是object，那么它永远不会编译。

Sure enough, if line 3 was int[] instead of object then it would never compile. Which brings me to a final question related to Q2.

Q3）为什么C＃在调试器和编译器中引发了转换/转换错误，而在运行时却没有？

Q3) Why does C# raise a cast/conversion error in the debugger and compiler but not at runtime?

Q2

为什么“int []是uint [] == true”在C＃

问题描述

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