C# 十六进制表示法和有符号整数
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Hexadecimal notation and signed integers
提问by kitsune
This is a follow up question. So, Java store's integers in two's-complementsand you can do the following:
这是一个后续问题。因此，Java 以二进制补码形式存储整数，您可以执行以下操作：
int ALPHA_MASK = 0xff000000;
In C# this requires the use of an unsigned integer, uint, because it interprets this to be 4278190080instead of -16777216.
在 C# 中，这需要使用无符号整数uint，因为它将其解释为4278190080而不是-16777216。
My question, how do declare negative values in hexadecimal notation in c#, and how exactly are integers represented internally? What are the differences to Java here?
我的问题是，如何在 c# 中以十六进制表示法声明负值，以及内部如何准确表示整数？这里与Java有什么区别？
采纳答案by Martin v. L?wis
C# (rather, .NET) also uses the two's complement, but it supports both signed and unsigned types (which Java doesn't). A bit mask is more naturally an unsigned thing - why should one bit be different than all the other bits?
C#（更确切地说，.NET）也使用二进制补码，但它同时支持有符号和无符号类型（Java 不支持）。位掩码更自然地是无符号的东西 - 为什么一位应该与所有其他位不同？
In this specific case, it is safe to use an unchecked cast:
在这种特定情况下，使用未经检查的强制转换是安全的：
int ALPHA_MASK = unchecked((int)0xFF000000);
To "directly" represent this number as a signed value, you write
要“直接”将此数字表示为有符号值，请编写
int ALPHA_MASK = -0x1000000; // == -16777216
Hexadecimal is not (or should not) be any different from decimal: to represent a negative number, you need to write a negative sign, followed by the digits representing the absolute value.
十六进制与十进制没有（或不应该）任何不同：要表示负数，您需要写一个负号，后跟表示绝对值的数字。
回答by Marc Gravell
Well, you can use an unchecked block and a cast:
好吧，您可以使用未经检查的块和强制转换：
unchecked
{
int ALPHA_MASK = (int)0xff000000;
}
or
或者
int ALPHA_MASK = unchecked((int)0xff000000);
Not terribly convenient, though... perhaps just use a literal integer?
不过不是很方便……也许只是使用文字整数？
回答by Quadko
And just to add insult to injury, this will work too:
只是为了雪上加霜，这也行得通：
-0x7F000000
