Nullable.GetUnderlyingType Method
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Returns the underlying type argument of the specified nullable type.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Shared Function GetUnderlyingType ( _
nullableType As Type _
) As Type
public static Type GetUnderlyingType(
Type nullableType
)
Parameters
- nullableType
Type: System.Type
A Type object that describes a closed generic nullable type.
Return Value
Type: System.Type
The type argument of the nullableType parameter, if the nullableType parameter is a closed generic nullable type; otherwise, nulla null reference (Nothing in Visual Basic).
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | nullableType is nulla null reference (Nothing in Visual Basic). |
Remarks
A generic type definition is a type declaration, such as Nullable<T>, that contains a type parameter list, and the type parameter list declares one or more type parameters. A closed generic type is a type declaration where a particular type is specified for a type parameter.
For example, if the nullableType parameter is the type of Nullable<Int32> in C# (Nullable(Of Int32) in Visual Basic), the return value is the type of Int32 (that is, the type argument of the closed generic type).
Examples
The following code example defines a method whose return value is of type Nullable<T> of Int32. The code example uses the GetUnderlyingType method to display the type argument of the return value.
' This code example demonstrates the
' Nullable.GetUnderlyingType() method.
Imports System.Reflection
Class Example
' Declare a type named Example.
' The MyMethod member of Example returns a Nullable of Int32.
Public Class Example
Public Function MyMethod() As Nullable(Of Integer)
Return 0
End Function
End Class
'
' Use reflection to obtain a Type object for the Example type.
' Use the Type object to obtain a MethodInfo object for the MyMethod method.
' Use the MethodInfo object to obtain the type of the return value of
' MyMethod, which is Nullable of Int32.
' Use the GetUnderlyingType method to obtain the type argument of the
' return value type, which is Int32.
'
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim t As Type = GetType(Example)
Dim mi As MethodInfo = t.GetMethod("MyMethod")
Dim retval As Type = mi.ReturnType
outputBlock.Text += String.Format("Return value type ... {0}", retval) & vbCrLf
Dim answer As Type = Nullable.GetUnderlyingType(retval)
outputBlock.Text += String.Format("Underlying type ..... {0}", answer) & vbCrLf
End Sub 'Main
End Class 'Sample
'
'This code example produces the following results:
'
'Return value type ... System.Nullable`1[System.Int32]
'Underlying type ..... System.Int32
'
// This code example demonstrates the
// Nullable.GetUnderlyingType() method.
using System;
using System.Reflection;
class Example
{
/*
Use reflection to obtain a Type object for the Sample type.
Use the Type object to obtain a MethodInfo object for the MyMethod method.
Use the MethodInfo object to obtain the type of the return value of
MyMethod, which is Nullable of Int32.
Use the GetUnderlyingType method to obtain the type argument of the
return value type, which is Int32.
*/
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
Type t = typeof(Sample);
MethodInfo mi = t.GetMethod("MyMethod");
Type retval = mi.ReturnType;
outputBlock.Text += String.Format("Return value type ... {0}", retval) + "\n";
Type answer = Nullable.GetUnderlyingType(retval);
outputBlock.Text += String.Format("Underlying type ..... {0}", answer) + "\n";
}
}
// Declare a type named Sample.
// The MyMethod member of Sample returns a Nullable of Int32.public class Sample
class Sample
{
public int? MyMethod()
{
return 0;
}
}
/*
This code example produces the following results:
Return value type ... System.Nullable`1[System.Int32]
Underlying type ..... System.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.