使用 [Flags] 属性定义 C# 枚举的多种方法？

发布于 2024-08-19 06:48:20 字数 554 浏览 4 评论 0原文

我了解枚举在 C# 中的工作原理，并且了解 Flags 属性给表带来的内容。

我在此处看到了这个问题。其中推荐第一种口味，但没有提供任何理由/理由。

这两者的定义方式是否存在差异，一个比另一个更好？使用第一个语法代替第二个有什么优点？在定义标志类型枚举时，我总是使用第二种风格......我一直都做错了吗？

[Serializable]
[Flags]
public enum SiteRoles
{
    User = 1 << 0,
    Admin = 1 << 1,
    Helpdesk = 1 << 2
}

这不就是一样吗

[Serializable]
[Flags]
public enum SiteRoles
{
    User = 1,
    Admin = 2,
    Helpdesk = 4
}

原文

I understand how Enums work in C#, and I get what the Flags attribute brings to the table.

I saw this question, here. Which recommends the first flavor, but doesn't provide any reason/justification for it.

Is there a difference in the way in which these two are defined, is one better than the other? What are the advantages to using the first synax as instead of the second? I've always used the second flavor when defining Flags type Enums... have I been doing it wrong all this time?

[Serializable]
[Flags]
public enum SiteRoles
{
    User = 1 << 0,
    Admin = 1 << 1,
    Helpdesk = 1 << 2
}

Is that not the same as

[Serializable]
[Flags]
public enum SiteRoles
{
    User = 1,
    Admin = 2,
    Helpdesk = 4
}

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难以启齿的温柔 2024-08-26 06:48:20

第一个的主要优点是您不需要计算每个标志的正确值，因为编译器会为您做这件事。除此之外，它们是相同的。

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醉殇 2024-08-26 06:48:20

考虑更复杂的示例：

[Flags]
public enum SiteRoles
{
    User = 1 << 12,
    Admin = 1 << 13,
    Helpdesk = 1 << 15,
    AdvancedUser = User | Helpdesk, //or (1<<12)|(1<<13)
}

[Flags]
public enum SiteRoles
{
    User = 4096, //not so obvious!
    Admin = 8192,
    Helpdesk = 16384,
    AdvancedUser = 12288, //!
}

[Flags]
public enum SiteRoles
{
    User = 0x1000, //we can use hexademical digits
    Admin = 0x2000,
    Helpdesk = 0x4000,
    AdvancedUser = 0x3000, //it much simpler calculate binary operator OR with hexademicals
}

此示例表明，在这种情况下，第一个版本的可读性要强得多。十进制文字并不是表示标志常量的最佳方式。有关按位运算（也可用于表示标志常量）的更多信息，请参阅 http://en。 wikipedia.org/wiki/Bitwise_operation

Consider more complex samples:

[Flags]
public enum SiteRoles
{
    User = 1 << 12,
    Admin = 1 << 13,
    Helpdesk = 1 << 15,
    AdvancedUser = User | Helpdesk, //or (1<<12)|(1<<13)
}

[Flags]
public enum SiteRoles
{
    User = 4096, //not so obvious!
    Admin = 8192,
    Helpdesk = 16384,
    AdvancedUser = 12288, //!
}

[Flags]
public enum SiteRoles
{
    User = 0x1000, //we can use hexademical digits
    Admin = 0x2000,
    Helpdesk = 0x4000,
    AdvancedUser = 0x3000, //it much simpler calculate binary operator OR with hexademicals
}

This samples shows that in this case first version is MUCH MORE readable. Decimal literals is not the best way to represent flag constants. And for more information about bitwise operations (that also can be used to represent flag constants) see http://en.wikipedia.org/wiki/Bitwise_operation

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