How do I select a random value from an enumeration?

Array values = Enum.GetValues(typeof(Bar));
Random random = new Random();
Bar randomBar = (Bar)values.GetValue(random.Next(values.Length));

Use Enum.GetValues to retrieve an array of all values. Then select a random array item.

static T RandomEnumValue<T> ()
{
    var v = Enum.GetValues (typeof (T));
    return (T) v.GetValue (new Random ().Next(v.Length));
}

测试:

for (int i = 0; i < 10; i++) {
    var value = RandomEnumValue<System.DayOfWeek> ();
    Console.WriteLine (value.ToString ());
}

-gt;

Tuesday
Saturday
Wednesday
Monday
Friday
Saturday
Saturday
Saturday
Friday
Wednesday

Updated: This answer originally used OrderBy (x => _Random.Next()).FirstOrDefault () to select a random element. Only use it if you are irrationally attracted to shuffling by random keys. In any other case, use the accepted answer by Darin Dimitrov instead, which I incorporated in this answer later.

呼叫 Enum.GetValues ;这将返回一个数组,该数组表示枚举的所有可能值。从这个数组中选择一个随机项。Cast that item back to the original enum type.

Here is a generic function for it. Keep the RNG creation outside the high frequency code.

public static Random RNG = new Random();

public static T RandomEnum<T>()
{  
    Type type = typeof(T);
    Array values = Enum.GetValues(type);
    lock(RNG)
    {
        object value= values.GetValue(RNG.Next(values.Length));
        return (T)Convert.ChangeType(value, type);
    }
}

使用实例:

System.Windows.Forms.Keys randomKey = RandomEnum<System.Windows.Forms.Keys>();

You could just do this:

var rnd = new Random();
return (MyEnum) rnd.Next(Enum.GetNames(typeof(MyEnum)).Length);

No need to store arrays

就我个人而言,我非常喜欢扩展方法,所以我会使用类似的方法(虽然不是真正的扩展,但看起来很相似):

public enum Options {
    Zero,
    One,
    Two,
    Three,
    Four,
    Five
}

public static class RandomEnum {
    private static Random _Random = new Random(Environment.TickCount);

    public static T Of<T>() {
        if (!typeof(T).IsEnum)
            throw new InvalidOperationException("Must use Enum type");

        Array enumValues = Enum.GetValues(typeof(T));
        return (T)enumValues.GetValue(_Random.Next(enumValues.Length));
    }
}

[TestClass]
public class RandomTests {
    [TestMethod]
    public void TestMethod1() {
        Options option;
        for (int i = 0; i < 10; ++i) {
            option = RandomEnum.Of<Options>();
            Console.WriteLine(option);
        }
    }

}

Here's an alternative version as an Extension Method 使用 LINQ .

using System;
using System.Linq;

public static class EnumExtensions
{
    public static Enum GetRandomEnumValue(this Type t)
    {
        return Enum.GetValues(t)          // get values from Type provided
            .OfType<Enum>()               // casts to Enum
            .OrderBy(e => Guid.NewGuid()) // mess with order of results
            .FirstOrDefault();            // take first item in result
    }
}

public static class Program
{
    public enum SomeEnum
    {
        One = 1,
        Two = 2,
        Three = 3,
        Four = 4
    }

    public static void Main()
    {
        for(int i=0; i < 10; i++)
        {
            Console.WriteLine(typeof(SomeEnum).GetRandomEnumValue());
        }
    }           
}

二
一
四
四
四
三
二
四
一
三