为什么标志枚举通常用十六进制值定义 [英] Why are flag enums usually defined with hexadecimal values

问题描述

很多时候我看到使用十六进制值的标志枚举声明.例如:

A lot of times I see flag enum declarations that use hexadecimal values. For example:

[Flags]
public enum MyEnum
{
    None  = 0x0,
    Flag1 = 0x1,
    Flag2 = 0x2,
    Flag3 = 0x4,
    Flag4 = 0x8,
    Flag5 = 0x10
}

当我声明一个枚举时，我通常是这样声明的:

When I declare an enum, I usually declare it like this:

[Flags]
public enum MyEnum
{
    None  = 0,
    Flag1 = 1,
    Flag2 = 2,
    Flag3 = 4,
    Flag4 = 8,
    Flag5 = 16
}

为什么有些人选择用十六进制而不是十进制写值有什么理由或理由?在我看来，使用十六进制值时更容易混淆，并且不小心写了 Flag5 = 0x16 而不是 Flag5 = 0x10.

Is there a reason or rationale to why some people choose to write the value in hexadecimal rather than decimal? The way I see it, it's easier to get confused when using hex values and accidentally write Flag5 = 0x16 instead of Flag5 = 0x10.

推荐答案

原理可能不同，但我看到的一个优点是十六进制提醒你:好吧，我们不是在任意人类发明的世界中处理数字不再以十为底.我们正在处理比特——机器的世界——我们将按照它的规则行事."除非您正在处理数据的内存布局很重要的相对较低级别的主题，否则很少使用十六进制.使用它暗示这就是我们现在所处的情况.

Rationales may differ, but an advantage I see is that hexadecimal reminds you: "Okay, we're not dealing with numbers in the arbitrary human-invented world of base ten anymore. We're dealing with bits - the machine's world - and we're gonna play by its rules." Hexadecimal is rarely used unless you're dealing with relatively low-level topics where the memory layout of data matters. Using it hints at the fact that that's the situation we're in now.

另外，我不确定 C#，但我知道在 C x <<y 是一个有效的编译时常量.使用位移似乎最清楚:

Also, i'm not sure about C#, but I know that in C x << y is a valid compile-time constant. Using bit shifts seems the most clear:

[Flags]
public enum MyEnum
{
    None  = 0,
    Flag1 = 1 << 0,  //1
    Flag2 = 1 << 1,  //2
    Flag3 = 1 << 2,  //4
    Flag4 = 1 << 3,  //8
    Flag5 = 1 << 4   //16
}

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