枚举标志属性C＃
这个问题在这里已经有了答案：
首先，您需要使用powers-of-2序列手动为您的值编号：
[Flags]
private enum MyEnum
{
Apple = 1,
Orange = 2,
Tomato = 4,
Potato = 8,
Melon = 16,
Watermelon = 32,
Fruit = Apple | Orange,
Vegetable = Tomato | Potato,
Berry = Melon | Watermelon,
}
[Flags]属性不是严格必要的，它只控制ToString()行为。
为了检查一个字符串是否与你的值匹配，你必须首先将它作为一个枚举：
private void Checking(string data)
{
//MyEnum v = (MyEnum) Enum.Parse(data);
MyEnum v = (MyEnum) Enum.Parse(typeof(MyEnum), data);
if((MyEnum.Fruit & v) != 0) MessageBox.Show("Fruit");
...
}
但请注意，像这样在Enum和字符串之间交换是有限的， Parse()是有限的。
除了Henk Holterman的解决方案，您还可以使用扩展方法：
[Flags]
private enum MyEnum {
None = 0,
Apple = 1,
Orange = 2,
Tomato = 4,
Potato = 8,
Melon = 16,
Watermelon = 32,
Berry = Melon | Watermelon,
Fruit = Apple | Orange,
Vegetable = Potato | Tomato
}
private static class MyEnumExtensions {
public static Boolean IsFruit(this MyEnum value) {
return (value & MyEnum.Fruit) == MyEnum.Fruit;
}
public static Boolean IsVegetable(this MyEnum value) {
return (value & MyEnum.Vegetable) == MyEnum.Vegetable;
}
public static Boolean IsBerry(this MyEnum value) {
return (value & MyEnum.Berry) == MyEnum.Berry;
}
}
...
MyEnum data = ...
if (data.IsBerry()) {
MessageBox.Show("Berry");
}
您也可以使用Enum类的HasFlag方法。 正如Henk指出的那样，需要使用2次幂次序的值手动为您的枚举赋值。
[Flags]
private enum MyEnum
{
Apple = 1,
Orange = 2,
Tomato = 4,
Potato = 8,
Melon 16,
Watermelon = 32,
Fruit = Apple | Orange,
Vegetable = Tomato | Potato,
Berry = Melon | Watermelon,
}
然后，检查您是否可以使用以下方法来处理枚举的所有组成部分：
void Cheking(string data)
{
// Get the enum value of the string passed to the method
MyEnum myEnumData;
if (Enum.TryParse<MyEnum>(data, out myEnumData))
{
// If the string was a valid enum value iterate over all the value of
// the underlying enum type
var values = Enum.GetValues(typeof(MyEnum)).OfType<MyEnum>();
foreach (var value in values)
{
// If the value is not a power of 2 it is a composed one. If it furthermore
// has the flag passed to the method this is one we searched.
var isPowerOfTwo = (value != 0) && ((value & (value - 1)) == 0);
if (!isPowerOfTwo && value.HasFlag(myEnumData))
{
MessageBox.Show(value.ToString());
}
}
}
// In case an invalid value had been passed to the method
// display an error message.
else
{
MessageBox.Show("Invalid Value");
}
}
或者使用LINQ以更短的方式编写它：
var results = Enum.GetValues(typeof(MyEnum))
.OfType<MyEnum>()
.Select(x => new { Value = x, IsPowerOfTwo = (x != 0) && ((x & (x - 1)) == 0) } )
.Where(x => !x.IsPowerOfTwo && x.Value.HasFlag(myEnumData))
.Select(x => x.Value.ToString());
这将给出一个包含结果的IEnumerable<string> 。 如果myEnumData的值为MyEnum.Apple则结果将只包含值"Fruit" 。