Nullable.GetUnderlyingType(Type) Método

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

public static Type GetUnderlyingType (Type nullableType);

public static Type? GetUnderlyingType (Type nullableType);

static member GetUnderlyingType : Type -> Type

Public Shared Function GetUnderlyingType (nullableType As Type) As Type

Parâmetros

Retornos

Type

O argumento de tipo do parâmetro nullableType, se o parâmetro nullableType for um tipo que permite valor nulo genérico fechado; caso contrário, null.

Exceções

Exemplos

O exemplo de código a seguir define um método cujo valor retornado é do tipo Nullable<T> .Int32 O exemplo de código usa o GetUnderlyingType método para exibir o argumento de tipo do valor retornado.

// This code example demonstrates the
// Nullable.GetUnderlyingType() method.

using System;
using System.Reflection;

class Sample
{
// Declare a type named Example.
// The MyMethod member of Example returns a Nullable of Int32.

    public class Example
    {
        public int? MyMethod()
        {
        return 0;
        }
    }

/*
   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 static void Main()
    {
        Type t = typeof(Example);
        MethodInfo mi = t.GetMethod("MyMethod");
        Type retval = mi.ReturnType;
        Console.WriteLine("Return value type ... {0}", retval);
        Type answer = Nullable.GetUnderlyingType(retval);
        Console.WriteLine("Underlying type ..... {0}", answer);
    }
}
/*
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.
open System

// Declare a type named Example.
// The MyMethod member of Example returns a Nullable of Int32.

type Example() =
    member _.MyMethod() =
        Nullable 0

(*
   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.
*)
let t = typeof<Example>
let mi = t.GetMethod "MyMethod"
let retval = mi.ReturnType
printfn $"Return value type ... {retval}"
let answer = Nullable.GetUnderlyingType retval
printfn $"Underlying type ..... {answer}"

// 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.

Imports System.Reflection

Class Sample
    ' 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 Main() 
        Dim t As Type = GetType(Example)
        Dim mi As MethodInfo = t.GetMethod("MyMethod")
        Dim retval As Type = mi.ReturnType
        Console.WriteLine("Return value type ... {0}", retval)
        Dim answer As Type = Nullable.GetUnderlyingType(retval)
        Console.WriteLine("Underlying type ..... {0}", answer)
    
    End Sub
End Class
'
'This code example produces the following results:
'
'Return value type ... System.Nullable`1[System.Int32]
'Underlying type ..... System.Int32
'

Comentários

Uma definição de tipo genérico é uma declaração de tipo, como Nullable<T>, que contém uma lista de parâmetros de tipo e a lista de parâmetros de tipo declara um ou mais parâmetros de tipo. Um tipo genérico fechado é uma declaração de tipo em que um tipo específico é especificado para um parâmetro de tipo.

Por exemplo, se o nullableType parâmetro for o tipo de Nullable<Int32> em C# (Nullable(Of Int32) em Visual Basic), o valor retornado será o tipo de Int32 (ou seja, o argumento de tipo do tipo genérico fechado).

Aplica-se a