C# Iterating through an enum? (Indexing a System.Array)

问题

I have the following code:

// Obtain the string names of all the elements within myEnum 
String[] names = Enum.GetNames( typeof( myEnum ) );

// Obtain the values of all the elements within myEnum 
Array values = Enum.GetValues( typeof( myEnum ) );

// Print the names and values to file
for ( int i = 0; i < names.Length; i++ )
{
    print( names[i], values[i] ); 
}

However, I cannot index values. Is there an easier way to do this?

Or have I missed something entirely!

回答1:

Array values = Enum.GetValues(typeof(myEnum));

foreach( MyEnum val in values )
{
   Console.WriteLine (String.Format("{0}: {1}", Enum.GetName(typeof(MyEnum), val), val));
}

Or, you can cast the System.Array that is returned:

string[] names = Enum.GetNames(typeof(MyEnum));
MyEnum[] values = (MyEnum[])Enum.GetValues(typeof(MyEnum));

for( int i = 0; i < names.Length; i++ )
{
    print(names[i], values[i]);
}

But, can you be sure that GetValues returns the values in the same order as GetNames returns the names ?

回答2:

You need to cast the array - the returned array is actually of the requested type, i.e. myEnum[] if you ask for typeof(myEnum):

myEnum[] values = (myEnum[]) Enum.GetValues(typeof(myEnum));

Then values[0] etc

回答3:

You can cast that Array to different types of Arrays:

myEnum[] values = (myEnum[])Enum.GetValues(typeof(myEnum));

or if you want the integer values:

int[] values = (int[])Enum.GetValues(typeof(myEnum));

You can iterate those casted arrays of course :)

回答4:

How about a dictionary list?

Dictionary<string, int> list = new Dictionary<string, int>();
foreach( var item in Enum.GetNames(typeof(MyEnum)) )
{
    list.Add(item, (int)Enum.Parse(typeof(MyEnum), item));
}

and of course you can change the dictionary value type to whatever your enum values are.

回答5:

Another solution, with interesting possibilities:

enum Days { Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday }

static class Helpers
{
public static IEnumerable<Days> AllDays(Days First)
{
  if (First == Days.Monday)
  {
     yield return Days.Monday;
     yield return Days.Tuesday;
     yield return Days.Wednesday;
     yield return Days.Thursday;
     yield return Days.Friday;
     yield return Days.Saturday;
     yield return Days.Sunday;
  } 

  if (First == Days.Saturday)
  {
     yield return Days.Saturday;
     yield return Days.Sunday;
     yield return Days.Monday;
     yield return Days.Tuesday;
     yield return Days.Wednesday;
     yield return Days.Thursday;
     yield return Days.Friday;
  } 
}

回答6:

Here is another. We had a need to provide friendly names for our EnumValues. We used the System.ComponentModel.DescriptionAttribute to show a custom string value for each enum value.

public static class StaticClass
{
    public static string GetEnumDescription(Enum currentEnum)
    {
        string description = String.Empty;
        DescriptionAttribute da;

        FieldInfo fi = currentEnum.GetType().
                    GetField(currentEnum.ToString());
        da = (DescriptionAttribute)Attribute.GetCustomAttribute(fi,
                    typeof(DescriptionAttribute));
        if (da != null)
            description = da.Description;
        else
            description = currentEnum.ToString();

        return description;
    }

    public static List<string> GetEnumFormattedNames<TEnum>()
    {
        var enumType = typeof(TEnum);
        if (enumType == typeof(Enum))
            throw new ArgumentException("typeof(TEnum) == System.Enum", "TEnum");

        if (!(enumType.IsEnum))
            throw new ArgumentException(String.Format("typeof({0}).IsEnum == false", enumType), "TEnum");

        List<string> formattedNames = new List<string>();
        var list = Enum.GetValues(enumType).OfType<TEnum>().ToList<TEnum>();

        foreach (TEnum item in list)
        {
            formattedNames.Add(GetEnumDescription(item as Enum));
        }

        return formattedNames;
    }
}

In Use

 public enum TestEnum
 { 
        [Description("Something 1")]
        Dr = 0,
        [Description("Something 2")]
        Mr = 1
 }



    static void Main(string[] args)
    {

        var vals = StaticClass.GetEnumFormattedNames<TestEnum>();
    }

This will end returning "Something 1", "Something 2"

回答7:

What about using a foreach loop, maybe you could work with that?

  int i = 0;
  foreach (var o in values)
  {
    print(names[i], o);
    i++;
  }

something like that perhaps?

回答8:

Old question, but a slightly cleaner approach using LINQ's .Cast<>()

var values = Enum.GetValues(typeof(MyEnum)).Cast<MyEnum>();

foreach(var val in values)
{
    Console.WriteLine("Member: {0}",val.ToString());     
}

回答9:

Array has a GetValue(Int32) method which you can use to retrieve the value at a specified index.

Array.GetValue

回答10:

You can simplify this using format strings. I use the following snippet in usage messages:

writer.WriteLine("Exit codes are a combination of the following:");
foreach (ExitCodes value in Enum.GetValues(typeof(ExitCodes)))
{
    writer.WriteLine("   {0,4:D}: {0:G}", value);
}

The D format specifier formats the enum value as a decimal. There's also an X specifier that gives hexadecimal output.

The G specifier formats an enum as a string. If the Flags attribute is applied to the enum then combined values are supported as well. There's an F specifier that acts as if Flags is always present.

See Enum.Format().

回答11:

In the Enum.GetValues results, casting to int produces the numeric value. Using ToString() produces the friendly name. No other calls to Enum.GetName are needed.

public enum MyEnum
{
    FirstWord,
    SecondWord,
    Another = 5
};

// later in some method  

 StringBuilder sb = new StringBuilder();
 foreach (var val in Enum.GetValues(typeof(MyEnum))) {
   int numberValue = (int)val;
   string friendyName = val.ToString();
   sb.Append("Enum number " + numberValue + " has the name " + friendyName + "\n");
 }
 File.WriteAllText(@"C:\temp\myfile.txt", sb.ToString());

 // Produces the output file contents:
 /*
 Enum number 0 has the name FirstWord
 Enum number 1 has the name SecondWord
 Enum number 5 has the name Another
 */

回答12:

Here is a simple way to iterate through your custom Enum object

For Each enumValue As Integer In [Enum].GetValues(GetType(MyEnum))

     Print([Enum].GetName(GetType(MyEnum), enumValue).ToString)

Next

回答13:

Ancient question, but 3Dave's answer supplied the easiest approach. I needed a little helper method to generate a Sql script to decode an enum value in the database for debugging. It worked great:

    public static string EnumToCheater<T>() {
        var sql = "";
        foreach (var enumValue in Enum.GetValues(typeof(T)))
            sql += $@"when {(int) enumValue} then '{enumValue}' ";
        return $@"case ?? {sql}else '??' end,";
    }

I have it in a static method, so usage is:

var cheater = MyStaticClass.EnumToCheater<MyEnum>()

来源：https://stackoverflow.com/questions/482729/c-sharp-iterating-through-an-enum-indexing-a-system-array

标签

enums

iteration

system.array