Convert Enum to String

Works for our project...

public static String convertToString(this Enum eff)
{
    return Enum.GetName(eff.GetType(), eff);
}

public static EnumType converToEnum<EnumType>(this String enumValue)  
{
    return (EnumType) Enum.Parse(typeof(EnumType), enumValue);
}

All of these internally end up calling a method called InternalGetValueAsString. The difference between ToString and GetName would be that GetName has to verify a few things first:

1. The type you entered isn't null.
2. The type you entered is, in fact an enumeration.
3. The value you passed in isn't null.
4. The value you passed in is of a type that an enumeration can actually use as it's underlying type, or of the type of the enumeration itself. It uses GetType on the value to check this.

.ToString doesn't have to worry about any of these above issues, because it is called on an instance of the class itself, and not on a passed in version, therefore, due to the fact that the .ToString method doesn't have the same verification issues as the static methods, I would conclude that .ToString is the fastest way to get the value as a string.

Best I can find is this unrelated question on MSDN, which contains an XML snippet that answers this question. Any of these methods share the same flaw: they call enum.toString(), which does not work properly when using Dotfuscation. Other concerns appear to relate to indirect boxing (GetName and Format). Unfortunately, I can't find any performance reasons for using any of the above.

Paraphrasing from the xml snippet,

Passing a boxed enum to string.Format() or any other function can result in enum.ToString() being called. This will cause problems when Dotfuscating. You should not use enum.ToString(), enum.GetNames(), enum.GetName(), enum.Format() or enum.Parse() to convert an enum to a string. Instead, use a switch statement, and also internationalize the names if necessary.

Enum.GetName()

Format() is really just a wrapper around GetName() with some formatting functionality (or InternalGetValueAsString() to be exact). ToString() is pretty much the same as Format(). I think GetName() is best option since it's totally obvious what it does for anyone who reads the source.

I create a "Description" extension method and attach it to the enum so that i can get truly user-friendly naming that includes spaces and casing. I have never liked using the enum value itself as displayable text because it is something we developers use to create more readable code. It is not intended for UI display purposes. I want to be able to change the UI without going through and changing enums all over.

I don't know what the "preferred" method is (ask 100 people and get 100 different opinions) but do what's simplest and what works. GetName works but requires a lot more keystrokes. ToString() seems to do the job very well.

For me the easiest way to Convert an Enum to String and vice-versa is:

// Sample for Enum.ToString(String)
using System;

class Sample
{
    enum Colors {Red, Yellow = 12};

    public static void Main()
    {
    Colors myColor = Colors.Yellow;

    Console.WriteLine("Colors.Red = {0}", Colors.Red.ToString("d"));
    Console.WriteLine("Colors.Yellow = {0}", Colors.Yellow.ToString("d"));

    Console.WriteLine("{0}myColor = Colors.Yellow{0}", Environment.NewLine);

    Console.WriteLine("myColor.ToString(\"g\") = {0}", myColor.ToString("g"));
    Console.WriteLine("myColor.ToString(\"G\") = {0}", myColor.ToString("G"));

    Console.WriteLine("myColor.ToString(\"x\") = {0}", myColor.ToString("x"));
    Console.WriteLine("myColor.ToString(\"X\") = {0}", myColor.ToString("X"));

    Console.WriteLine("myColor.ToString(\"d\") = {0}", myColor.ToString("d"));
    Console.WriteLine("myColor.ToString(\"D\") = {0}", myColor.ToString("D"));

    Console.WriteLine("myColor.ToString(\"f\") = {0}", myColor.ToString("f"));
    Console.WriteLine("myColor.ToString(\"F\") = {0}", myColor.ToString("F"));
    }
}
/*
This example produces the following results:
Colors.Red = 0
Colors.Yellow = 12

myColor = Colors.Yellow

myColor.ToString("g") = Yellow
myColor.ToString("G") = Yellow
myColor.ToString("x") = 0000000C
myColor.ToString("X") = 0000000C
myColor.ToString("d") = 12
myColor.ToString("D") = 12
myColor.ToString("f") = Yellow
myColor.ToString("F") = Yellow
*/ 

Now to convert the selected string back to Enum you can just Parse it:

var myYellowEnum = Enum.Parse(typeof (Colors), "Yellow"); // Returns Yellow

ToString() gives the most obvious result from a readability perspective, while using Enum.GetName() requires a bit more mental parsing to quickly understand what its trying to do (unless you see the pattern all the time).

From a pure performance point of view, as already provided in @nawfal's answer, Enum.GetName() is better.

If performance is really your goal though, it would be even better to provide a look-up beforehand (using a Dictionary or some other mapping).

In C++/CLI, this would look like

Dictionary<String^, MyEnum> mapping;
for each (MyEnum field in Enum::GetValues(MyEnum::typeid))
{
    mapping.Add(Enum::GetName(MyEnum::typeid), field);
}

Comparison using an enum of 100 items and 1000000 iterations:

Enum.GetName: ~800ms
.ToString(): ~1600ms
Dictionary mapping: ~250ms

With new Roslyn warnings this question got me thinking. My research led me to 2 libraries. Both show better performance than the built-in .NET 5 methods ToString, GetName, etc. Take a look at benchmarks:

Enums.NET

FastEnum