将 Float 转换为 Long 给出负值

Question

为什么向后转换会给出 -ve 表达式？

float f = long.MaxValue;

Console.WriteLine("long to float: {0}",f);
Console.WriteLine("long Max: {0}",long.MaxValue);
Console.WriteLine("float to long casting: {0}",(long)f);
//Console.WriteLine("converting float to long: {0}",Convert.ToInt64(f));
//Above statement gives OverflowExection as expected.

---

输出：

long to float: 9.223372E+18
long Max: 9223372036854775807
float to long casting: -9223372036854775808

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同样，long.MinValue 给出了正确的结果。

Answer 1

正如评论中 M.kazem 所建议的那样，它导致了溢出，并且根据 C# 规范，编译器默默地忽略了它

Console.WriteLine("float to long casting: {0}",(long)f);

但是如果我们将上面的代码转换为 under checked 则会抛出一个溢出表达式。

checked 
{
   Console.WriteLine("float to long casting: {0}",(long)f);
}