C#•12mo ago

❔ How to get a random enum value?

I have a function here where I would like to get a random value from an enum type. The goal is to give NextValue any enum type, and it will calculate its length and return a random value. The cast on return isn't working. Is this possible to do?

public static T NextValue<T>() where T : Enum
        {
            return (T)Rand.Next(0, Enum.GetNames(typeof(T)).Length - 1);
        }

public static T NextValue<T>() where T : Enum
        {
            return (T)Rand.Next(0, Enum.GetNames(typeof(T)).Length - 1);
        }

18 Replies

Aaron•12mo ago

you want GetValues, not GetNames

TheRanger•12mo ago

iirc its return (T)(object)Rand.Next

Aaron•12mo ago

and also that well, no okay

triplemocha•12mo ago

Appears to be working:

        public static T NextValue<T>() where T : Enum
        {
            return (T)(object)Rand.Next(0, Enum.GetValues(typeof(T)).Length - 1);
        }

        public static T NextValue<T>() where T : Enum
        {
            return (T)(object)Rand.Next(0, Enum.GetValues(typeof(T)).Length - 1);
        }

Aaron•12mo ago

public static T NextValue<T>() where T : struct
{
    var values = Enum.GetValues<T>();
    return values[Rand.Next(0, values.Length)];
}

public static T NextValue<T>() where T : struct
{
    var values = Enum.GetValues<T>();
    return values[Rand.Next(0, values.Length)];
}

that

triplemocha•12mo ago

I got this message:

Aaron•12mo ago

did you get the edit I made I swapped it from T : Enum to T : struct

triplemocha•12mo ago

I did.

TheRanger•12mo ago

remove the - 1 or ull never get the last value

Aaron•12mo ago

no that just doesn't work

enum E
{
    Value = 50
}

enum E
{
    Value = 50
}

triplemocha•12mo ago

Same thing. It's a custom Random class I made, so last value is max - 1.

TheRanger•12mo ago

this works for me

    public static T NextValue<T>() where T : Enum
    {
        var values = (T[])Enum.GetValues(typeof(T));
        return values[Random.Shared.Next(0, values.Length)];
    }

    public static T NextValue<T>() where T : Enum
    {
        var values = (T[])Enum.GetValues(typeof(T));
        return values[Random.Shared.Next(0, values.Length)];
    }

Aaron•12mo ago

ah okay make the constraint unmanaged, Enum

public static T NextValue<T>() where T : unmanaged, Enum
{
    var values = Enum.GetValues<T>();
    return values[Rand.Next(0, values.Length)];
}

public static T NextValue<T>() where T : unmanaged, Enum
{
    var values = Enum.GetValues<T>();
    return values[Rand.Next(0, values.Length)];
}

triplemocha•12mo ago

Seems to be working. Thanks! unmanaged is new to me.

Aaron•12mo ago

I think struct, Enum might also work? unmanaged just means there are no objects in it, which applies so enums, so that's what I'm used to using

TheRanger•12mo ago

works

triplemocha•12mo ago

Ah, I see.

Accord•12mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ How to get a random enum value?