Enum evaluation in c#

Question

Say I have enum as follows (taken from MSDN example):

enum Days {Sat=1, Sun, Mon, Tue, Wed, Thu, Fri};

I can then use is in the code as follows:

int today = (int)Days.Sun;

Question:

Can I evaluate enums? Say I have a variable Day whose value is "Sun". Will Days.Day evaluate to Days.Sun?

Thanks!

Please don't get hung up on the days example and tell me I should use comparison etc...i am looking to replace the usage of arrays with enums as it is more compact. So what I am looking for is essentially an ability to retrieve values from enum similar to an array:

myArray[Day] where day will evaluate to array key....

Answer 1

Yes, you can do that. You can freely cast between an enum and its underlying type.

using System;

class Program
{
    static void Main()
    {
     // prints "zero"
     Console.WriteLine((Foo)0);
     // prints "1"
     Console.WriteLine((int)Foo.one);
    }
}

enum Foo { zero, one, two };

Answer 2

Am I right in saying you've got:

string day = "Sun";

and you want to get back the value Days.Sun?

If so, use:

string day = "Sun";
Day day = (Day) Enum.Parse(typeof(Days), day);

Answer 3

for int yes , but for string you should do something like this

Answer 4

You can also parse the string values as well. Using Enum.Parse

[TestFixture]
public class EnumParsingSO
{
 public enum Days
 {
  Sat = 1,
  Sun,
  Mon,
  Tues
 }

 [Test]
 public void EnumFromString()
 {
  Days expected = Days.Mon;
  int expectedInt = 3;
  Days actual = (Days)Enum.Parse(typeof(Days), "Mon");

  Assert.AreEqual(expected, actual);
  Assert.AreEqual(expectedInt, (int)actual);
 }
}

Answer 5

As Andrew says, you can cast from an enum to its underlying type. You can also unbox between the two as well, and there's an implicit conversion from the constant 0 to any enum type:

using System;

enum Demo { Foo, Bar, Baz };

class Test
{
    static void Main()
    {
        int i = 2;
        object o = i;
        // Unboxing from int to Demo
        Demo d = (Demo) o;
        Console.WriteLine(d);

        o = Demo.Baz;
        // Unboxing from Demo to int
        i = (int) o;
        Console.WriteLine(i);

        // Implicit conversion of 0
        d = 0;
        Console.WriteLine(d);
    }
}

Answer 6

Yes you can, you just need to provide the native integer value for each enum value. From your example:

enum Days {
    Sat=1, 
    Sun=2, 
    Mon=3, 
    Tue=4, 
    Wed=5, 
    Thu=6, 
    Fri=7
};

(Now, why you would order days of the week in this way is beyond me...)