HasFlag始终返回True [英] HasFlag always returns True

问题描述

有一种方法可以检查我在一系列标志中是否有标志？

There is a way to check if I got a flag in a series of flag?

示例：

[Flags]
Enum TestEnum
{
  ALIVE, DEAD, ALMOSTDEAD, HURT, OTHERS

}
// check if is alive and has been hurt
TestEnum aTest = TestEnum.ALIVE | TestEnum.HURT
bool aTest2 = aTest.HasFlag(TestEnum.ALIVE)

但是 a.Test.HasFlag 始终返回true，即使没有TestEnum.ALIVE

But a.Test.HasFlag always returns true, even without the TestEnum.ALIVE

推荐答案

您当然可以像所有人一样使用 Enum.HasFlag 建议。但是，重要的是要确保您的枚举采用2的幂。两位的幂只有一个位，因此您的枚举应如下所示：

You can certainly use Enum.HasFlag like everyone has suggested. However, its important to make sure that your enumeration falls in powers of two. Powers of two have a single bit set, so your enumeration should look like this:

Enum TestEnum
{
    ALIVE = 1, DEAD = 2, ALMOSTDEAD = 4, HURT = 8, OTHERS = 16
}

之所以重要，是因为您正在比较位标志。在内存中，您的枚举标志将如下所示：

The reason this is important is because you are comparing the bit flags. In memory, your enum flags will look like this:

ALIVE      = 00001
DEAD       = 00010
ALMOSTDEAD = 00100
HURT       = 01000
OTHERS     = 10000

按位操作时比较，例如 DEAD | ALMOSTDEAD ，您正在执行以下操作：

When you do a bitwise compare, like DEAD | ALMOSTDEAD, you are doing this:

DEAD       = 00010
           OR
ALMOSTDEAD = 00100
------------------
RESULT     = 00110

由于结果>> 0，所以它为true。

Since the Result is > then 0, its true.

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