How can I reference a specific enumeration by an integer?

Question

namespace ChemicalTest
{

    enum Echemicals { oxygen, hydrogen, carbon }

    public class Chemicals
    {
        int[] chemicals = new int[3];

        public Chemicals()
        {
            foreach (int i in chemicals)
            {
                int[i] = //How can I reference each enumeration here?
                         //For example (pseudocode) - (i)Echemicals
            }
        }
    }
}

I have three enum values: oxygen {0}, hydrogen{1}, carbon{2}

I'd like to put each of these enums into an array to later be referenced by their own number, so that I could call them from the array.

I can use (int)Echemicals.hydrogen to return the default value of the second enumeration {1} but I don't know how to do this in reverse.

I am trying to store each of the names of the chemicals in an array by calling them by their integer value.

I'm very confused about the purpose of what you're trying to do. But to answer your question, you just cast the int to the enum type like `(Echemicals)1` will give you `Echemicals.hydrogen`. — itsme86, Nov 10 '17 at 14:09
What is your actual requirement? I think you are confused and try to make us also confused — sujith karivelil, Nov 10 '17 at 14:10

score 0 · Answer 1 · answered Nov 10 '17 at 14:11

0

You just need to cast to your enum:

Echemicals val = (Echemicals)i;

But you don't need to use int[] for this. Maybe you should give more details as to what the issue is.

answered Nov 10 '17 at 14:11

Ric

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15ee8f99-57ff-4f92-890c-b56153 · Answer 2 · 2017-11-10T14:20:44.843

By default, enum values in .NET are assigned integer values in order of declaration, starting at zero. Hence, with this enum...

enum Echemicals { oxygen, hydrogen, carbon }

int zero = (int)Echemicals.oxygen;
int one = (int)Echemicals.hydrogen;
int two = (int)Echemicals.carbon;

And vice versa:

Echemicals oxy = = (Echemicals)0;

But chemicals is an array of integers, not Echemicals. So it sounds like you want this:

int[i] = i;

If at some other time you want to convert int[2] into the Echemicals value corresponding to that integer value,

Echemicals chem = (Echemicals)int[2];

But if you want an array of all the Echemicals enum values, this will work -- and it'll be more useful than that array of integers:

var echemValues = (Echemicals[])Enum.GetValues(typeof(Echemicals));

Echemicals oxy = echemValues[0];

int thisWillBeZero = (int)echemValues[0];

You can also assign the integer values explicitly when you define the enum type:

enum Echemicals { oxygen = 8, hydrogen = 1, carbon = 6 }

score 0 · Answer 3 · answered Nov 10 '17 at 14:16

0

I believe it is easier if you do it the other way around, first get all enums and than cast them to integer:

var enumValues = Enum.GetValues(typeof(Echemicals));
var decimals = enumValues.OfType<Echemicals>().Select(x => (int)x).ToArray();

answered Nov 10 '17 at 14:16

Rand Random

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score 0 · Answer 4 · answered Nov 10 '17 at 14:25

You can do something like this:

enum Echemicals { 
    oxygen = 1, 
    hydrogen = 2, 
    carbon = 3 
}
// ...
int oxigenInt = (int) Echemicals.oxygen;
Echemicals oxigenEnum = (Echemicals) 1;

Alternatively you can use the Immutable Object Design:

public class Echemicals {
    private int index;

    private Echemicals(int index) {
        this.index = index;
    }

    public static Echemicals _Oxygen = new Echemicals(1);
    public static Echemicals Oxygen { get { return _Oxygen; } }

    // Other elements

    // A list of all values:
    public static Echemicals[] _Values;
    public static Echemicals[] Values { get { return _Values; } }

    static Echemicals() {
        _Values = new[] {Oxygen, /*other elements*/};
    }

    static Echemicals GetByIndex(index) {
        return Values.FirstOrDefault(e => e.index == index);
    }
}

A lot more work, but useful if you need more properties in that element other than just the index.

How can I reference a specific enumeration by an integer?

4 Answers4