convert an enum to another type of enum

I have an enum of for example 'Gender' (Male =0 , Female =1) and I have another enum from a service which has its own Gender enum (Male =0 , Female =1, Unknown =2)

My question is how can I write something quick and nice to convert from their enum to mine?

Solution 1:

Given Enum1 value = ..., then if you mean by name:

Enum2 value2 = (Enum2) Enum.Parse(typeof(Enum2), value.ToString());

If you mean by numeric value, you can usually just cast:

Enum2 value2 = (Enum2)value;

(with the cast, you might want to use Enum.IsDefined to check for valid values, though)

Solution 2:

Using an extension method works quite neatly, when using the two conversion methods suggested by Nate:

public static class TheirGenderExtensions
{
    public static MyGender ToMyGender(this TheirGender value)
    {
        // insert switch statement here
    }
}

public static class MyGenderExtensions
{
    public static TheirGender ToTheirGender(this MyGender value)
    {
        // insert switch statement here
    }
}

Obviously there's no need to use separate classes if you don't want to. My preference is to keep extension methods grouped by the classes/structures/enumerations they apply to.

Solution 3:

Just cast one to int and then cast it to the other enum (considering that you want the mapping done based on value):

Gender2 gender2 = (Gender2)((int)gender1);

Solution 4:

If we have:

enum Gender
{
    M = 0,
    F = 1,
    U = 2
}

and

enum Gender2
{
    Male = 0,
    Female = 1,
    Unknown = 2
}

We can safely do

var gender = Gender.M;
var gender2   = (Gender2)(int)gender;

Or even

var enumOfGender2Type = (Gender2)0;

If you want to cover the case where an enum on the right side of the '=' sign has more values than the enum on the left side - you will have to write your own method/dictionary to cover that as others suggested.