如何在C#中将int转换为枚举?
当前回答
这是一个标志枚举感知安全转换方法:
public static bool TryConvertToEnum<T>(this int instance, out T result)
where T: Enum
{
var enumType = typeof (T);
var success = Enum.IsDefined(enumType, instance);
if (success)
{
result = (T)Enum.ToObject(enumType, instance);
}
else
{
result = default(T);
}
return success;
}
其他回答
向Enum转换和从Enum转换的不同方式
enum orientation : byte
{
north = 1,
south = 2,
east = 3,
west = 4
}
class Program
{
static void Main(string[] args)
{
orientation myDirection = orientation.north;
Console.WriteLine(“myDirection = {0}”, myDirection); //output myDirection =north
Console.WriteLine((byte)myDirection); //output 1
string strDir = Convert.ToString(myDirection);
Console.WriteLine(strDir); //output north
string myString = “north”; //to convert string to Enum
myDirection = (orientation)Enum.Parse(typeof(orientation),myString);
}
}
你应该建立一些类型匹配的放松机制,以更加健壮。
public static T ToEnum<T>(dynamic value)
{
if (value == null)
{
// default value of an enum is the object that corresponds to
// the default value of its underlying type
// https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/default-values-table
value = Activator.CreateInstance(Enum.GetUnderlyingType(typeof(T)));
}
else if (value is string name)
{
return (T)Enum.Parse(typeof(T), name);
}
return (T)Enum.ToObject(typeof(T),
Convert.ChangeType(value, Enum.GetUnderlyingType(typeof(T))));
}
测试用例
[Flags]
public enum A : uint
{
None = 0,
X = 1 < 0,
Y = 1 < 1
}
static void Main(string[] args)
{
var value = EnumHelper.ToEnum<A>(7m);
var x = value.HasFlag(A.X); // true
var y = value.HasFlag(A.Y); // true
var value2 = EnumHelper.ToEnum<A>("X");
var value3 = EnumHelper.ToEnum<A>(null);
Console.ReadKey();
}
从int:
YourEnum foo = (YourEnum)yourInt;
从字符串:
YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);
// The foo.ToString().Contains(",") check is necessary for
// enumerations marked with a [Flags] attribute.
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
throw new InvalidOperationException(
$"{yourString} is not an underlying value of the YourEnum enumeration."
);
}
从一个数字:
YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum), yourInt);
简单地,可以将int强制转换为enum
public enum DaysOfWeeks
{
Monday = 1,
Tuesday = 2,
Wednesday = 3,
Thursday = 4,
Friday = 5,
Saturday = 6,
Sunday = 7,
}
var day= (DaysOfWeeks)5;
Console.WriteLine("Day is : {0}", day);
Console.ReadLine();
我更喜欢使用可为null的枚举类型变量。
var enumValue = (MyEnum?)enumInt;
if (!enumValue.HasValue)
{
throw new ArgumentException(nameof(enumValue));
}
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