ValueType ValueType ValueType ValueType Class

Définition

Fournit la classe de base pour les types valeur.Provides the base class for value types.

public ref class ValueType abstract
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public abstract class ValueType
type ValueType = class
Public MustInherit Class ValueType
Héritage
ValueTypeValueTypeValueTypeValueType
Dérivé
Attributs

Remarques

ValueType substitue les méthodes virtuelles à partir de Object des implémentations plus appropriées pour les types valeur.ValueType overrides the virtual methods from Object with more appropriate implementations for value types. Voir aussi Enum, qui hérite de ValueType.See also Enum, which inherits from ValueType.

Types de données sont divisés en types valeur et types référence.Data types are separated into value types and reference types. Les types valeur sont soit alloué par la pile soit allouées inline dans une structure.Value types are either stack-allocated or allocated inline in a structure. Les types référence sont alloués par tas.Reference types are heap-allocated. Les types référence et valeur sont dérivés de la classe de base fondamentale Object.Both reference and value types are derived from the ultimate base class Object. Dans les cas où il est nécessaire pour un type valeur se comporte comme un objet, un wrapper qui rende le type de valeur à un objet de référence est alloué sur le tas et valeur la valeur du type d’y est copié.In cases where it is necessary for a value type to behave like an object, a wrapper that makes the value type look like a reference object is allocated on the heap, and the value type's value is copied into it. Le wrapper est marqué pour que le système sache qu’il contient un type valeur.The wrapper is marked so the system knows that it contains a value type. Ce processus est appelé conversion boxing et le processus inverse est appelé unboxing.This process is known as boxing, and the reverse process is known as unboxing. Boxing et unboxing permettent à n’importe quel type devant être traitée en tant qu’objet.Boxing and unboxing allow any type to be treated as an object.

Bien que ValueType est la classe de base implicite pour les types valeur, vous ne peut pas créer une classe qui hérite de ValueType directement.Although ValueType is the implicit base class for value types, you cannot create a class that inherits from ValueType directly. Au lieu de cela, les compilateurs individuels fournissent un mot clé de langage ou de construction (tel que struct en C# et Structure...End StructureInstead, individual compilers provide a language keyword or construct (such as struct in C# and StructureEnd Structure en Visual Basic) pour prendre en charge la création de types de valeur.in Visual Basic) to support the creation of value types.

En plus de servir de la classe de base pour les types de valeur dans le .NET Framework, le ValueType structure n’est généralement pas utilisée directement dans le code.Aside from serving as the base class for value types in the .NET Framework, the ValueType structure is generally not used directly in code. Toutefois, il peut être utilisé en tant que paramètre dans les appels de méthode pour restreindre les arguments possibles pour les types de valeur au lieu de tous les objets, ou autoriser une méthode pour gérer un nombre de types de valeur différente.However, it can be used as a parameter in method calls to restrict possible arguments to value types instead of all objects, or to permit a method to handle a number of different value types. L’exemple suivant illustre comment ValueType empêche le passé aux méthodes des types référence.The following example illustrates how ValueType prevents reference types from being passed to methods. Il définit une classe nommée Utility qui contient quatre méthodes : IsNumeric, qui indique si son argument est un nombre ; IsInteger, qui indique si son argument est un entier ; IsFloat, qui indique si son argument est un nombre à virgule flottante ; et Compare, ce qui indique la relation entre deux valeurs numériques.It defines a class named Utility that contains four methods: IsNumeric, which indicates whether its argument is a number; IsInteger, which indicates whether its argument is an integer; IsFloat, which indicates whether its argument is a floating-point number; and Compare, which indicates the relationship between two numeric values. Dans chaque cas, les paramètres de méthode sont de type ValueType, et les types référence ne peuvent pas être passés aux méthodes.In each case, the method parameters are of type ValueType, and reference types are prevented from being passed to the methods.

using System;
using System.Numerics;


public class Utility
{
   public enum NumericRelationship {
      GreaterThan = 1, 
      EqualTo = 0,
      LessThan = -1
   };
   
   public static NumericRelationship Compare(ValueType value1, ValueType value2)
   {
      if (! IsNumeric(value1)) 
         throw new ArgumentException("value1 is not a number.");
      else if (! IsNumeric(value2))
         throw new ArgumentException("value2 is not a number.");

      // Use BigInteger as common integral type
      if (IsInteger(value1) && IsInteger(value2)) {
         BigInteger bigint1 = (BigInteger) value1;
         BigInteger bigint2 = (BigInteger) value2;
         return (NumericRelationship) BigInteger.Compare(bigint1, bigint2);
      }
      // At least one value is floating point; use Double.
      else {
         Double dbl1 = 0;
         Double dbl2 = 0;
         try {
            dbl1 = Convert.ToDouble(value1);
         }
         catch (OverflowException) {
            Console.WriteLine("value1 is outside the range of a Double.");
         }
         try {
            dbl2 = Convert.ToDouble(value2);
         }
         catch (OverflowException) {
            Console.WriteLine("value2 is outside the range of a Double.");
         }
         return (NumericRelationship) dbl1.CompareTo(dbl2);
      }
   }
   
   public static bool IsInteger(ValueType value)
   {         
      return (value is SByte || value is Int16 || value is Int32 
              || value is Int64 || value is Byte || value is UInt16  
              || value is UInt32 || value is UInt64 
              || value is BigInteger); 
   }

   public static bool IsFloat(ValueType value) 
   {         
      return (value is float | value is double | value is Decimal);
   }

   public static bool IsNumeric(ValueType value)
   {
      return (value is Byte ||
              value is Int16 ||
              value is Int32 ||
              value is Int64 ||
              value is SByte ||
              value is UInt16 ||
              value is UInt32 ||
              value is UInt64 ||
              value is BigInteger ||
              value is Decimal ||
              value is Double ||
              value is Single);
   }
}
Imports System.Numerics

Public Class Utility
   Public Enum NumericRelationship As Integer
      GreaterThan = 1
      EqualTo = 0
      LessThan = -1
   End Enum
      
   Public Shared Function Compare(value1 As ValueType, value2 As ValueType) _
                                  As NumericRelationship
      If Not IsNumeric(value1) Then 
         Throw New ArgumentException("value1 is not a number.")
      Else If Not IsNumeric(value2) Then
         Throw New ArgumentException("value2 is not a number.")
      Else
         ' Use BigInteger as common integral type
         If isInteger(value1) And IsInteger(value2) Then
            Dim bigint1 As BigInteger = CType(value1, BigInteger)
            Dim bigInt2 As BigInteger = CType(value2, BigInteger)
            Return CType(BigInteger.Compare(bigint1, bigint2), NumericRelationship)
         ' At least one value is floating point; use Double.
         Else   
            Dim dbl1, dbl2 As Double
            Try
               dbl1 = CDbl(value1)
            Catch e As OverflowException
               Console.WriteLine("value1 is outside the range of a Double.")
            End Try
               
            Try
               dbl2 = CDbl(value2)
            Catch e As OverflowException
               Console.WriteLine("value2 is outside the range of a Double.")
            End Try
            Return CType(dbl1.CompareTo(dbl2), NumericRelationship)
         End If
      End If
   End Function
   
   Public Shared Function IsInteger(value As ValueType) As Boolean         
      Return (TypeOf value Is SByte Or TypeOf value Is Int16 Or TypeOf value Is Int32 _
                 Or TypeOf value Is Int64 Or TypeOf value Is Byte Or TypeOf value Is UInt16 _ 
                 Or TypeOf value Is UInt32 Or TypeOf value Is UInt64 _
                 Or TypeOf value Is BigInteger) 
   End Function

   Public Shared Function IsFloat(value As ValueType) As Boolean         
      Return (TypeOf value Is Single Or TypeOf value Is Double Or TypeOf value Is Decimal)
   End Function

   Public Shared Function IsNumeric(value As ValueType) As Boolean
      Return TypeOf value Is Byte OrElse
         TypeOf value Is Int16 OrElse
         TypeOf value Is Int32 OrElse
         TypeOf value Is Int64 OrElse
         TypeOf value Is SByte OrElse
         TypeOf value Is UInt16 OrElse
         TypeOf value Is UInt32 OrElse
         TypeOf value Is UInt64 OrElse
         TypeOf value Is BigInteger OrElse
         TypeOf value Is Decimal OrElse
         TypeOf value Is Double OrElse
         TypeOf value Is Single
   End Function
End Class

L’exemple suivant illustre des appels aux méthodes de la Utility classe.The following example illustrates calls to the methods of the Utility class.

public class Example
{
   public static void Main()
   {
      Console.WriteLine(Utility.IsNumeric(12));
      Console.WriteLine(Utility.IsNumeric(true));
      Console.WriteLine(Utility.IsNumeric('c'));
      Console.WriteLine(Utility.IsNumeric(new DateTime(2012, 1, 1)));
      Console.WriteLine(Utility.IsInteger(12.2));
      Console.WriteLine(Utility.IsInteger(123456789));
      Console.WriteLine(Utility.IsFloat(true));
      Console.WriteLine(Utility.IsFloat(12.2));
      Console.WriteLine(Utility.IsFloat(12));
      Console.WriteLine("{0} {1} {2}", 12.1, Utility.Compare(12.1, 12), 12);
   }
}
// The example displays the following output:
//       True
//       False
//       False
//       False
//       False
//       True
//       False
//       True
//       False
//       12.1 GreaterThan 12
Module Example
   Public Sub Main()
      Console.WriteLine(Utility.IsNumeric(12))
      Console.WriteLine(Utility.IsNumeric(True))
      Console.WriteLine(Utility.IsNumeric("c"c))
      Console.WriteLine(Utility.IsNumeric(#01/01/2012#))
      Console.WriteLine(Utility.IsInteger(12.2))
      Console.WriteLine(Utility.IsInteger(123456789))
      Console.WriteLine(Utility.IsFloat(True))
      Console.WriteLine(Utility.IsFloat(12.2))
      Console.WriteLine(Utility.IsFloat(12))
      Console.WriteLine("{0} {1} {2}", 12.1, Utility.Compare(12.1, 12), 12)
   End Sub
End Module
' The example displays the following output:
'       True
'       False
'       False
'       False
'       False
'       True
'       False
'       True
'       False
'       12.1 GreaterThan 12

Constructeurs

ValueType() ValueType() ValueType() ValueType()

Initialise une nouvelle instance de la classe ValueType.Initializes a new instance of the ValueType class.

Méthodes

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Indique si cette instance et un objet spécifié sont égaux.Indicates whether this instance and a specified object are equal.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Retourne le code de hachage de cette instance.Returns the hash code for this instance.

GetType() GetType() GetType() GetType()

Obtient le Type de l'instance actuelle.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Crée une copie superficielle du Object actuel.Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

Retourne le nom de type qualifié complet de cette instance.Returns the fully qualified type name of this instance.

S’applique à

Voir aussi