将枚举转换为字符串

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 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.

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.

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.

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.

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);
}

Enum.GetName(...)

This is the most elegant method that is meant for it.

var enumValueString = Enum.GetName(typeof (MyEnum), MyEnum.MyValue);

Although I don't see any issues with calling .ToString() as it is simply shorter.

var enumValueString = MyEnum.MyValue.ToString();

With new C# 6 syntax you can use:

nameof(MyEnum.MyValue)

In my tests, Enum.GetName was faster and by decent margin. Internally ToString calls Enum.GetName. From source for .NET 4.0, the essentials:

public override String ToString()
{
return Enum.InternalFormat((RuntimeType)GetType(), GetValue());
}


private static String InternalFormat(RuntimeType eT, Object value)
{
if (!eT.IsDefined(typeof(System.FlagsAttribute), false))
{
String retval = GetName(eT, value); //<== the one
if (retval == null)
return value.ToString();
else
return retval;
}
else
{
return InternalFlagsFormat(eT, value);
}
}

I cant say that is the reason for sure, but tests state one is faster than the other. Both the calls involve boxing (in fact they are reflection calls, you're essentially retrieving field names) and can be slow for your liking.

Test setup: enum with 8 values, no. of iterations = 1000000

Result: Enum.GetName => 700 ms, ToString => 2000 ms

If speed isn't noticeable, I wouldn't care and use ToString since it offers a much cleaner call. Contrast

Enum.GetName(typeof(Bla), value)

with

value.ToString()

Simple: enum names into a List:

List<String> NameList = Enum.GetNames(typeof(YourEnumName)).Cast<string>().ToList()

As of C#6 the best way to get the name of an enum is the new nameof operator:

nameof(MyEnum.EnumValue);


// Ouputs
> "EnumValue"

This works at compile time, with the enum being replaced by the string in the compiled result, which in turn means this is the fastest way possible.

Any use of enum names does interfere with code obfuscation, if you consider obfuscation of enum names to be worthwhile or important - that's probably a whole other question.

This would work too.

    List<string> names = Enum.GetNames(typeof(MyEnum)).ToList();

For VB aficionados:

EnumStringValue = System.Enum.GetName(GetType(MyEnum), MyEnumValue)

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

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

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