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

Question

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!

Answer 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 ?

Answer 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

Answer 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 :)

Answer 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.

Answer 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;
  } 
}

Answer 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"

Answer 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?

Answer 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());     
}

Answer 9

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

Array.GetValue

Answer 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().

Answer 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
 */

Answer 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

Answer 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>()