为什么Enumerable.Cast引发InvalidCastException？ [英] Why Enumerable.Cast raises an InvalidCastException?

问题描述

如果我可以将整数值隐式转换为双精度值，例如：

If I can implicitly cast an integer value to a double, like:

int a = 4;    
double b = a;
// now b holds 4.0

为什么我不能这样做：

int[] intNumbers = {10, 6, 1, 9};    
double[] doubleNumbers2 = intNumbers.Cast<double>().ToArray();

我收到指定的转换无效 InvalidCastException 异常。

I get a "Specified cast is not valid" InvalidCastException exception.

相反（从双精度转换为整数）会导致相同的错误。

Doing the opposite (casting from double to int) results in the same error.

我在做什么错了？

推荐答案

好吧，您对 Cast ，仅此而已-它的目的是处理装箱/拆箱，参考和身份转换，仅此而已。不幸的是，文档不够清晰：（

Well, you have incorrect expectations of Cast, that's all - it's meant to deal with boxing/unboxing, reference and identity conversions, and that's all. It's unfortunate that the documentation isn't as clear as it might be :(

解决方案是使用 Select ：

doubleNumbers2 = intNumbers.Select(x => (double) x).ToArray();

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