Article
11/18/2011

Enum.GetUnderlyingType Method

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Returns the underlying type of the specified enumeration.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Shared Function GetUnderlyingType ( _
    enumType As Type _
) As Type

[ComVisibleAttribute(true)]
public static Type GetUnderlyingType(
    Type enumType
)

Parameters

enumType
Type: System.Type
The enumeration whose underlying type will be retrieved.

Return Value

Type: System.Type
The underlying type of enumType.

Exceptions

Exception	Condition
ArgumentNullException	enumType is nulla null reference (Nothing in Visual Basic).
ArgumentException	enumType is not an Enum.

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.

Examples

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

Module Example
   Public Sub Demo(outputBlock As System.Windows.Controls.TextBlock)
      Dim enumValues() As [Enum] = { DayOfWeek.Monday, PlatformID.Win32NT, 
                                     DateTimeKind.Utc, StringComparison.Ordinal }
      outputBlock.FontFamily = New FontFamily("Courier New") 
      outputBlock.Text += String.Format("{0,-10} {1, 18}   {2,15}", 
                         "Member", "Enumeration", "Underlying Type") + vbCrLf
      outputBlock.Text += vbCrLf
      For Each enumValue In enumValues
         DisplayEnumInfo(outputBlock, enumValue)
      Next
   End Sub

   Sub DisplayEnumInfo(outputBlock As System.Windows.Controls.TextBlock, 
                       enumValue As [Enum])
      Dim enumType As Type = enumValue.GetType()
      Dim underlyingType As Type = [Enum].GetUnderlyingType(enumType)
      outputBlock.Text += String.Format("{0,-10} {1, 18}   {2,15}",
                                        enumValue, enumType.Name, 
                                        underlyingType.Name) + vbCrLf   
   End Sub
End Module
' The example displays the following output:
'       Member            Enumeration   Underlying Type
'       
'       Monday              DayOfWeek             Int32
'       Win32NT            PlatformID             Int32
'       Utc              DateTimeKind             Int32
'       Ordinal      StringComparison             Int32

using System;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Enum[] enumValues = { DayOfWeek.Monday, PlatformID.Win32NT, 
                            DateTimeKind.Utc, StringComparison.Ordinal };

      outputBlock.FontFamily = new System.Windows.Media.FontFamily("Courier New");
      outputBlock.Text += String.Format("{0,-10} {1, 18}   {2,15}\n\n", 
                                   "Member", "Enumeration", "Underlying Type");
      foreach (var enumValue in enumValues)
         DisplayEnumInfo(outputBlock, enumValue);
   }

   static void DisplayEnumInfo(System.Windows.Controls.TextBlock outputBlock,
                               Enum enumValue)
   {
      Type enumType = enumValue.GetType();
      Type underlyingType = Enum.GetUnderlyingType(enumType);
      outputBlock.Text += String.Format("{0,-10} {1, 18}   {2,15}\n",
                                        enumValue, enumType.Name, 
                                        underlyingType.Name);   
   }
}
// The example displays the following output:
//       Member            Enumeration   Underlying Type
//       
//       Monday              DayOfWeek             Int32
//       Win32NT            PlatformID             Int32
//       Utc              DateTimeKind             Int32
//       Ordinal      StringComparison             Int32

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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