Enum.GetUnderlyingType(Type) Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

Enum.cs

Returns the underlying type of the specified enumeration.

public:
 static Type ^ GetUnderlyingType(Type ^ enumType);

public static Type GetUnderlyingType (Type enumType);

static member GetUnderlyingType : Type -> Type

Public Shared Function GetUnderlyingType (enumType As Type) As Type

Parameters

enumType

Type

The enumeration whose underlying type will be retrieved.

Returns

Type

The underlying type of enumType.

Exceptions

ArgumentNullException

enumType is null.

ArgumentException

enumType is not an Enum.

Examples

The following example calls the GetUnderlyingType method to display the underlying type of some enumeration members.

using System;

public class Example
{
   public static void Main()
   {
      Enum[] enumValues = { ConsoleColor.Red, DayOfWeek.Monday,
                            MidpointRounding.ToEven, PlatformID.Win32NT,
                            DateTimeKind.Utc, StringComparison.Ordinal };
      Console.WriteLine("{0,-10} {1, 18}   {2,15}\n",
                        "Member", "Enumeration", "Underlying Type");
      foreach (var enumValue in enumValues)
         DisplayEnumInfo(enumValue);
   }

   static void DisplayEnumInfo(Enum enumValue)
   {
      Type enumType = enumValue.GetType();
      Type underlyingType = Enum.GetUnderlyingType(enumType);
      Console.WriteLine("{0,-10} {1, 18}   {2,15}",
                        enumValue, enumType.Name, underlyingType.Name);
   }
}
// The example displays the following output:
//       Member            Enumeration   Underlying Type
//
//       Red              ConsoleColor             Int32
//       Monday              DayOfWeek             Int32
//       ToEven       MidpointRounding             Int32
//       Win32NT            PlatformID             Int32
//       Utc              DateTimeKind             Int32
//       Ordinal      StringComparison             Int32

open System

let displayEnumInfo (enumValue: Enum) =
    let enumType = enumValue.GetType()
    let underlyingType = Enum.GetUnderlyingType enumType
    printfn $"{enumValue,-10} {enumType.Name, 18}   {underlyingType.Name,15}"

let enumValues: Enum list =
    [ ConsoleColor.Red; DayOfWeek.Monday
      MidpointRounding.ToEven; PlatformID.Win32NT
      DateTimeKind.Utc; StringComparison.Ordinal ]

printfn "%-10s %18s   %15s\n" "Member" "Enumeration" "Underlying Type"
for enumValue in enumValues do
    displayEnumInfo enumValue

// The example displays the following output:
//       Member            Enumeration   Underlying Type
//
//       Red              ConsoleColor             Int32
//       Monday              DayOfWeek             Int32
//       ToEven       MidpointRounding             Int32
//       Win32NT            PlatformID             Int32
//       Utc              DateTimeKind             Int32
//       Ordinal      StringComparison             Int32

Module Example
   Public Sub Main()
      Dim enumValues() As [Enum] = { ConsoleColor.Red, DayOfWeek.Monday, 
                                     MidpointRounding.ToEven, PlatformID.Win32NT, 
                                     DateTimeKind.Utc, StringComparison.Ordinal }
      Console.WriteLine("{0,-10} {1, 18}   {2,15}", 
                        "Member", "Enumeration", "Underlying Type")
      Console.WriteLine()
      For Each enumValue In enumValues
         DisplayEnumInfo(enumValue)
      Next
   End Sub

   Sub DisplayEnumInfo(enumValue As [Enum])
      Dim enumType As Type = enumValue.GetType()
      Dim underlyingType As Type = [Enum].GetUnderlyingType(enumType)
      Console.WriteLine("{0,-10} {1, 18}   {2,15}",
                        enumValue, enumType.Name, underlyingType.Name)   
   End Sub
End Module
' The example displays the following output:
'       Member            Enumeration   Underlying Type
'       
'       Red              ConsoleColor             Int32
'       Monday              DayOfWeek             Int32
'       ToEven       MidpointRounding             Int32
'       Win32NT            PlatformID             Int32
'       Utc              DateTimeKind             Int32
'       Ordinal      StringComparison             Int32

Remarks

The Enum structure enables values to be represented as named constants. The data type of the enumeration's values is known as its underlying type. For example, the underlying type of the DayOfWeek enumeration, which consists of constants that represent each day of the week (DayOfWeek.Monday, DayOfWeek.Tuesday, and so on), is Int32.

See also

• GetTypeCode()