8

我有以下枚举标志：

[Flags]
private enum MemoryProtection: uint
{
    None             = 0x000,
    NoAccess         = 0x001,
    ReadOnly         = 0x002,
    ReadWrite        = 0x004,
    WriteCopy        = 0x008,
    Execute          = 0x010,
    ExecuteRead      = 0x020,
    ExecuteReadWrite = 0x040,
    ExecuteWriteCopy = 0x080,
    Guard            = 0x100,
    NoCache          = 0x200,
    WriteCombine     = 0x400,
    Readable         = (ReadOnly | ReadWrite | ExecuteRead | ExecuteReadWrite),
    Writable         = (ReadWrite | WriteCopy | ExecuteReadWrite | ExecuteWriteCopy)
}

现在我有一个枚举实例，我需要检查它是否可读。如果我使用以下代码：

myMemoryProtection.HasFlag(MemoryProtection.Readable)

在我的情况下它总是返回 false 因为我认为 HasFlag 检查它是否有每个标志。我需要一些优雅的东西来避免这样做：

myMemoryProtection.HasFlag(MemoryProtection.ReadOnly)         ||
myMemoryProtection.HasFlag(MemoryProtection.ReadWrite)        ||
myMemoryProtection.HasFlag(MemoryProtection.ExecuteRead)      ||
myMemoryProtection.HasFlag(MemoryProtection.ExecuteReadWrite)

我该怎么做？

4

3 回答 3

9

您可以翻转条件，并检查复合材料enum是否具有标志，而不是检查复合材料的标志，如下所示：

if (MemoryProtection.Readable.HasFlag(myMemoryProtection)) {
    ...
}

这是一个例子：

MemoryProtection a = MemoryProtection.ExecuteRead;
if (MemoryProtection.Readable.HasFlag(a)) {
    Console.WriteLine("Readable");
}
if (MemoryProtection.Writable.HasFlag(a)) {
    Console.WriteLine("Writable");
}

这打印Readable。

于 2013-04-25T00:41:29.533 回答
4

尝试按位运算符：

[TestMethod]
public void FlagsTest()
{
    MemoryProtection mp = MemoryProtection.ReadOnly | MemoryProtection.ReadWrite | MemoryProtection.ExecuteRead | MemoryProtection.ExecuteReadWrite;
    MemoryProtection value = MemoryProtection.Readable | MemoryProtection.Writable;
    Assert.IsTrue((value & mp) == mp);
}
于 2013-04-25T00:41:40.567 回答
4

是的，hasFlag检查是否设置了每个位字段（标志）。

与其将Readable其视为名称中包含的所有保护措施的组合Read，您能否扭转组合？例如

[Flags]
private enum MemoryProtection: uint
{
    NoAccess         = 0x000,
    Read             = 0x001,
    Write            = 0x002,
    Execute          = 0x004,
    Copy             = 0x008,
    Guard            = 0x010,
    NoCache          = 0x020,
    ReadOnly         = Read,
    ReadWrite        = (Read | Write),
    WriteCopy        = (Write | Copy),
    // etc.
    NoAccess         = 0x800
}

然后你可以编写如下代码：

myMemoryProtection.HasFlag(MemoryProtection.Read)
于 2013-04-25T00:53:10.393 回答