具有负号的无符号整数字面量 [英] Unsigned Integer Literal Having Negative Sign

问题描述

今天我遇到了这种奇怪的行为，有人可以解释为什么会发生这种情况吗?

Today I came a cross this strange behaviour, could someone explain why it happens?

var x = -1U; // When using -1UL it complains though.
Console.WriteLine(x.GetType().Name);
Console.WriteLine(x);

输出:

Int64

-1

MSDN说:

如果文字以U或u结尾，则具有可以表示其值的第一种类型:uint，ulong.

If the literal is suffixed by U or u, it has the first of these types in which its value can be represented: uint, ulong.

https://msdn.microsoft.com/en-us/library/aa664674％28v = vs.71％29.aspx

推荐答案

您的困惑源于您将其解释为数字 -1 ，后接 U .它实际上是数字 1U 的否定-.如问题中的引号所示，该数字 1U 的类型为 uint .取反 uint 会产生 long .

Your confusion stems from you interpreting this as the number -1, followed by a suffix U. It's actually the negation - of the number 1U. That number 1U has type uint, as indicated by the quote in your question. Negating an uint produces a long.

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