ValueType ValueType ValueType ValueType Class

定義

提供實值型別 (Value Type) 的基底類別。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
繼承
ValueTypeValueTypeValueTypeValueType
衍生
屬性

備註

ValueTypeObject使用更適當的實值型別來覆寫的虛擬方法。ValueType overrides the virtual methods from Object with more appropriate implementations for value types. 另請參閱ValueType ,它Enum會繼承自。See also Enum, which inherits from ValueType.

資料類型會分成實數值型別和參考型別。Data types are separated into value types and reference types. 實值型別在結構中是堆疊配置或配置的內嵌。Value types are either stack-allocated or allocated inline in a structure. 參考型別為堆積配置。Reference types are heap-allocated. 參考和實數值型別都是衍生自最終基類ObjectBoth reference and value types are derived from the ultimate base class Object. 如果實值型別的行為就像物件, 則會在堆積上配置值型別看起來像參考物件的包裝函式, 然後將實值型別的值複製到其中。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. 包裝函式已標記為, 因此系統知道它包含實值型別。The wrapper is marked so the system knows that it contains a value type. 此程式稱為「裝箱」, 而「反向」程式則稱為「取消裝箱」。This process is known as boxing, and the reverse process is known as unboxing. 「裝箱」和「取消裝箱」可讓任何類型被視為物件。Boxing and unboxing allow any type to be treated as an object.

雖然ValueType是實數值型別的隱含基類, 但您無法建立直接繼承自ValueType的類別。Although ValueType is the implicit base class for value types, you cannot create a class that inherits from ValueType directly. 相反地, 個別編譯器會提供語言關鍵字或結構 (例如struct在C#和Structure中 ...End StructureInstead, individual compilers provide a language keyword or construct (such as struct in C# and StructureEnd Structure 在 Visual Basic) 支援建立實數值型別。in Visual Basic) to support the creation of value types.

除了做為 .NET Framework 中實值型別的基類外, ValueType結構通常不會直接在程式碼中使用。Aside from serving as the base class for value types in the .NET Framework, the ValueType structure is generally not used directly in code. 不過, 它可以用來做為方法呼叫中的參數, 以限制數值型別的可能引數, 而不是所有物件, 或允許方法處理一些不同的實數值型別。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. 下列範例說明如何ValueType防止將參考型別傳遞至方法。The following example illustrates how ValueType prevents reference types from being passed to methods. 它會定義名為Utility的類別, 其中包含IsNumeric四個方法:, 指出其引數是否為數字;IsInteger, 指出其引數是否為整數。, 指出其引數是否為浮點數, 和Compare表示兩個數值之間的關聯性。 IsFloatIt 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. 在每個案例中, 方法參數的類型ValueType都是, 而參考型別則無法傳遞至方法。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

下列範例說明呼叫Utility類別的方法。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

建構函式

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

初始化 ValueType 類別的新執行個體。Initializes a new instance of the ValueType class.

方法

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

指示這個執行個體和指定的物件是否相等。Indicates whether this instance and a specified object are equal.

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

傳回這個執行個體的雜湊碼。Returns the hash code for this instance.

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

取得目前執行個體的 TypeGets the Type of the current instance.

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

建立目前 Object 的淺層複本 (Shallow Copy)。Creates a shallow copy of the current Object.

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

傳回此執行個體的完整類型名稱。Returns the fully qualified type name of this instance.

適用於

另請參閱