Getting Enum Associated with Int Value

Get int value from enum in C#

Just cast the enum, e.g.

int something = (int) Question.Role;

The above will work for the vast majority of enums you see in the wild, as the default underlying type for an enum is int.

However, as cecilphillip points out, enums can have different underlying types.
If an enum is declared as a uint, long, or ulong, it should be cast to the type of the enum; e.g. for

enum StarsInMilkyWay:long {Sun = 1, V645Centauri = 2 .. Wolf424B = 2147483649};

you should use

long something = (long)StarsInMilkyWay.Wolf424B;

Getting enum associated with int value

EDIT August 2018

Today I would implement this as follows

public enum LegNo {
    NO_LEG(-1), LEG_ONE(1), LEG_TWO(2);

    private final int value;

    LegNo(int value) {
        this.value = value;
    }

    public static Optional<LegNo> valueOf(int value) {
        return Arrays.stream(values())
            .filter(legNo -> legNo.value == value)
            .findFirst();
    }
}

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You'll have to maintain a mapping inside the enum.

public enum LegNo {
    NO_LEG(-1), LEG_ONE(1), LEG_TWO(2);

    private int legNo;

    private static Map<Integer, LegNo> map = new HashMap<Integer, LegNo>();

    static {
        for (LegNo legEnum : LegNo.values()) {
            map.put(legEnum.legNo, legEnum);
        }
    }

    private LegNo(final int leg) { legNo = leg; }

    public static LegNo valueOf(int legNo) {
        return map.get(legNo);
    }
}

The static block will be invoked only once, so there is practically no performance issue here.

EDIT: Renamed the method to valueOf as it is more inline with other Java classes.

Associate enum value to integer

It is possible, but not by invoking the enum's constructor, as it's available only within the enum itself.

What you can do is add a static method in your enum that retrieves the correct instance based on a given value, e.g. ZERO if the given value is 0.

Then you'd invoke that method in your other class when given the int argument.

Self contained example

public class Main {
    static enum Numbers {
        // various instances associated with integers or not
        ZERO(0),ONE(1),FORTY_TWO(42), DEFAULT;
        // int value
        private int value;
        // empty constructor for default value
        Numbers() {}
        // constructor with value
        Numbers(int value) {
            this.value = value;
        }
        // getter for value
        public int getValue() {
            return value;
        }
        // utility method to retrieve instance by int value
        public static Numbers forValue(int value) {
            // iterating values
            for (Numbers n: values()) {
                // matches argument
                if (n.getValue() == value) return n;
            }
            // no match, returning DEFAULT
            return DEFAULT;
        }
    }
    public static void main(String[] args) throws Exception {
        System.out.println(Numbers.forValue(42));
        System.out.println(Numbers.forValue(10));
    }
}

Output

FORTY_TWO
DEFAULT

How to get the int for enum value in Enumeration

To answer your question "how can I get the integer for string value":

To convert from a string into an enum, and then convert the resulting enum to an int, you can do this:

public enum Animals
{
    dog = 0,
    cat = 1,
    rat = 2
}

...

Animals answer;

if (Enum.TryParse("CAT", true, out answer))
{
    int value = (int) answer;
    Console.WriteLine(value);
}

By the way, normal enum naming convention dictates that you should not pluralize your enum name unless it represents flag values (powers of two) where multiple bits can be set - so you should call it Animal, not Animals.

give an int number to enum and get its related value as string in c++

If you really can't use an array (which would be by far the easiest way), you could build a function with a switch case:

enum difficulty
{
    Easy = 1,
    Normal,
    Hard
};

std::string diff_name(difficulty d) {
    switch(d) {
        case Easy: return "Easy";
        case Normal: return "Normal";
        case Hard: return "Hard";
        default: return std::string();
    }
}

And then in main you could do

cout << "choice: ";
cin >> choice;

std::cout << "You chose: " 
          << diff_name(static_cast<difficulty>(choice)) << std::endl;

associating int value to enum and getting corresponding int value

You do not need the map to retrieve code from an enum object, because the call of TAXSLAB.getCode(s) produces the same value as s.getCode():

TAXSLAB s = ...
int c1 = TAXSLAB.getCode(s);
int c2 = s.getCode();
// c1 == c2 here

int code is a field of enum TAXSLAB object, so you can get it directly.

This works for values associated with an enum from within the enum. If you need to associate a value with an enum outside the enum, the most performant way of doing it is by using EnumMap class designed specifically for this purpose.

How to get integer values from Enum in c#

Basically you cam use Enum.Parse to parse the string and then cast to int like below :

var str  = "value1";
var value = (int)Enum.Parse<MyEnum>(str);

Fiddle

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