IConvertible 介面 (System) | Microsoft Learn

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public interface class IConvertible

[System.CLSCompliant(false)]
public interface IConvertible

[System.CLSCompliant(false)]
[System.Runtime.InteropServices.ComVisible(true)]
public interface IConvertible

[<System.CLSCompliant(false)>]
type IConvertible = interface

[<System.CLSCompliant(false)>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type IConvertible = interface

Public Interface IConvertible

System.Boolean

下列程式碼範例示範複數類別的 IConvertible 實作，允許先將 Double 它轉換成，然後在該 Double 上呼叫靜態 Convert 成員。


   #using <System.dll>
using namespace System;
/// Class that implements IConvertible
ref class Complex: public IConvertible
private:
   double x;
   double y;
public:
   Complex( double x, double y )
      this->x = x;
      this->y = y;
   virtual TypeCode GetTypeCode()
      return TypeCode::Object;
   virtual bool ToBoolean( IFormatProvider^ /*provider*/ ) = IConvertible::ToBoolean
      if ( (x != 0.0) || (y != 0.0) )
            return true;
            return false;
   double GetDoubleValue()
      return Math::Sqrt( x * x + y * y );
   virtual Byte ToByte( IFormatProvider^ /*provider*/ ) = IConvertible::ToByte
      return Convert::ToByte( GetDoubleValue() );
   virtual Char ToChar( IFormatProvider^ /*provider*/ ) = IConvertible::ToChar
      return Convert::ToChar( GetDoubleValue() );
   virtual DateTime ToDateTime( IFormatProvider^ /*provider*/ ) = IConvertible::ToDateTime
      return Convert::ToDateTime( GetDoubleValue() );
   virtual Decimal ToDecimal( IFormatProvider^ /*provider*/ ) = IConvertible::ToDecimal
      return Convert::ToDecimal( GetDoubleValue() );
   virtual double ToDouble( IFormatProvider^ /*provider*/ ) = IConvertible::ToDouble
      return GetDoubleValue();
   virtual short ToInt16( IFormatProvider^ /*provider*/ ) = IConvertible::ToInt16
      return Convert::ToInt16( GetDoubleValue() );
   virtual int ToInt32( IFormatProvider^ /*provider*/ ) = IConvertible::ToInt32
      return Convert::ToInt32( GetDoubleValue() );
   virtual Int64 ToInt64( IFormatProvider^ /*provider*/ ) = IConvertible::ToInt64
      return Convert::ToInt64( GetDoubleValue() );
   virtual signed char ToSByte( IFormatProvider^ /*provider*/ ) = IConvertible::ToSByte
      return Convert::ToSByte( GetDoubleValue() );
   virtual float ToSingle( IFormatProvider^ /*provider*/ ) = IConvertible::ToSingle
      return Convert::ToSingle( GetDoubleValue() );
   virtual String^ ToString( IFormatProvider^ /*provider*/ ) = IConvertible::ToString
      return String::Format( "( {0} , {1} )", x, y );
   virtual Object^ ToType( Type^ conversionType, IFormatProvider^ /*provider*/ ) = IConvertible::ToType
      return Convert::ChangeType( GetDoubleValue(), conversionType );
   virtual UInt16 ToUInt16( IFormatProvider^ /*provider*/ ) = IConvertible::ToUInt16
      return Convert::ToUInt16( GetDoubleValue() );
   virtual UInt32 ToUInt32( IFormatProvider^ /*provider*/ ) = IConvertible::ToUInt32
      return Convert::ToUInt32( GetDoubleValue() );
   virtual UInt64 ToUInt64( IFormatProvider^ /*provider*/ ) = IConvertible::ToUInt64
      return Convert::ToUInt64( GetDoubleValue() );
void WriteObjectInfo( Object^ testObject )
   TypeCode typeCode = Type::GetTypeCode( testObject->GetType() );
   switch ( typeCode )
      case TypeCode::Boolean:
         Console::WriteLine( "Boolean: {0}", testObject );
         break;
      case TypeCode::Double:
         Console::WriteLine( "Double: {0}", testObject );
         break;
      default:
         Console::WriteLine( "{0}: {1}", typeCode, testObject );
         break;
int main()
   Complex^ testComplex = gcnew Complex( 4,7 );
   WriteObjectInfo( testComplex );
   WriteObjectInfo( Convert::ToBoolean( testComplex ) );
   WriteObjectInfo( Convert::ToDecimal( testComplex ) );
   WriteObjectInfo( Convert::ToString( testComplex ) );
   
    using System;
namespace ConsoleApplication2
    /// Class that implements IConvertible
    class Complex : IConvertible
        double	x;
        double	y;
        public Complex(double x, double y)
            this.x = x;
            this.y = y;
        public TypeCode GetTypeCode()
            return TypeCode.Object;
        bool IConvertible.ToBoolean(IFormatProvider provider)
            if(	(x != 0.0) || (y != 0.0) )
                return true;
                return false;
        double GetDoubleValue()
            return Math.Sqrt(x*x + y*y);
        byte IConvertible.ToByte(IFormatProvider provider)
            return Convert.ToByte(GetDoubleValue());
        char IConvertible.ToChar(IFormatProvider provider)
            return Convert.ToChar(GetDoubleValue());
        DateTime IConvertible.ToDateTime(IFormatProvider provider)
            return Convert.ToDateTime(GetDoubleValue());
        decimal IConvertible.ToDecimal(IFormatProvider provider)
            return Convert.ToDecimal(GetDoubleValue());
        double IConvertible.ToDouble(IFormatProvider provider)
            return GetDoubleValue();
        short IConvertible.ToInt16(IFormatProvider provider)
            return Convert.ToInt16(GetDoubleValue());
        int IConvertible.ToInt32(IFormatProvider provider)
            return Convert.ToInt32(GetDoubleValue());
        long IConvertible.ToInt64(IFormatProvider provider)
            return Convert.ToInt64(GetDoubleValue());
        sbyte IConvertible.ToSByte(IFormatProvider provider)
            return Convert.ToSByte(GetDoubleValue());
        float IConvertible.ToSingle(IFormatProvider provider)
            return Convert.ToSingle(GetDoubleValue());
        string IConvertible.ToString(IFormatProvider provider)
            return String.Format("({0}, {1})", x, y);
        object IConvertible.ToType(Type conversionType, IFormatProvider provider)
            return Convert.ChangeType(GetDoubleValue(),conversionType);
        ushort IConvertible.ToUInt16(IFormatProvider provider)
            return Convert.ToUInt16(GetDoubleValue());
        uint IConvertible.ToUInt32(IFormatProvider provider)
            return Convert.ToUInt32(GetDoubleValue());
        ulong IConvertible.ToUInt64(IFormatProvider provider)
            return Convert.ToUInt64(GetDoubleValue());
    /// <summary>
    /// Summary description for Class1.
    /// </summary>
    class Class1
        static void Main(string[] args)
            Complex		testComplex = new Complex(4,7);
            WriteObjectInfo(testComplex);
            WriteObjectInfo(Convert.ToBoolean(testComplex));
            WriteObjectInfo(Convert.ToDecimal(testComplex));
            WriteObjectInfo(Convert.ToString(testComplex));
        static void WriteObjectInfo(object testObject)
            TypeCode	typeCode = Type.GetTypeCode( testObject.GetType() );
            switch( typeCode )
                case TypeCode.Boolean:
                    Console.WriteLine("Boolean: {0}", testObject);
                    break;
                case TypeCode.Double:
                    Console.WriteLine("Double: {0}", testObject);
                    break;
                default:
                    Console.WriteLine("{0}: {1}", typeCode.ToString(), testObject);
                    break;
    
     open System
/// Class that implements IConvertible
type Complex(x, y) =
    member _.GetDoubleValue() =
        sqrt (x * x + y * y)
    interface IConvertible with
        member _.GetTypeCode() =
            TypeCode.Object
        member _.ToBoolean(provider: IFormatProvider) =
            (x <> 0.) || (y <> 0.)
        member this.ToByte(provider: IFormatProvider) =
            Convert.ToByte(this.GetDoubleValue())
        member this.ToChar(provider: IFormatProvider) =
            Convert.ToChar(this.GetDoubleValue())
        member this.ToDateTime(provider: IFormatProvider) =
            Convert.ToDateTime(this.GetDoubleValue())
        member this.ToDecimal(provider: IFormatProvider) =
            Convert.ToDecimal(this.GetDoubleValue())
        member this.ToDouble(provider: IFormatProvider) =
            this.GetDoubleValue()
        member this.ToInt16(provider: IFormatProvider) =
            Convert.ToInt16(this.GetDoubleValue())
        member this.ToInt32(provider: IFormatProvider) =
            Convert.ToInt32(this.GetDoubleValue())
        member this.ToInt64(provider: IFormatProvider) =
            Convert.ToInt64(this.GetDoubleValue())
        member this.ToSByte(provider: IFormatProvider) =
            Convert.ToSByte(this.GetDoubleValue())
        member this.ToSingle(provider: IFormatProvider) =
            Convert.ToSingle(this.GetDoubleValue())
        member _.ToString(provider: IFormatProvider) =
            $"({x}, {y})"
        member this.ToType(conversionType: Type, provider: IFormatProvider) =
            Convert.ChangeType(this.GetDoubleValue(), conversionType)
        member this.ToUInt16(provider: IFormatProvider) =
            Convert.ToUInt16(this.GetDoubleValue())
        member this.ToUInt32(provider: IFormatProvider) =
            Convert.ToUInt32(this.GetDoubleValue())
        member this.ToUInt64(provider: IFormatProvider) =
            Convert.ToUInt64(this.GetDoubleValue())
let writeObjectInfo testObject =
    let typeCode = Type.GetTypeCode(testObject.GetType())
    match typeCode with
    | TypeCode.Boolean ->
        printfn $"Boolean: {testObject}"
    | TypeCode.Double ->
        printfn $"Boolean: {testObject}"
    | _ ->
        printfn $"{typeCode}: {testObject}"
let testComplex = Complex(4, 7)
writeObjectInfo testComplex
writeObjectInfo (Convert.ToBoolean testComplex)
writeObjectInfo (Convert.ToDecimal testComplex)
writeObjectInfo (Convert.ToString testComplex)
     
      Public Class Complex : Implements IConvertible
   Private x, y As Double
   Public Sub New(ByVal x As Double, ByVal y As Double)
      Me.x = x
      Me.y = y
   End Sub
   Function GetDoubleValue() As Double
      Return Math.Sqrt((x * x + y * y))
   End Function
   ' The remaining code provides IConvertible method implementations.
   Public Function GetTypeCode() As TypeCode Implements IConvertible.GetTypeCode
      Return TypeCode.Object
   End Function
   Function ToBoolean(ByVal provider As IFormatProvider) As Boolean _
            Implements IConvertible.ToBoolean
      Return x <> 0 OrElse y <> 0
   End Function
   Function ToByte(ByVal provider As IFormatProvider) As Byte Implements IConvertible.ToByte
       Return Convert.ToByte(GetDoubleValue())
   End Function
   Function ToChar(ByVal provider As IFormatProvider) As Char Implements IConvertible.ToChar
      Return Convert.ToChar(GetDoubleValue())
   End Function
   Function ToDateTime(ByVal provider As IFormatProvider) As DateTime Implements IConvertible.ToDateTime
      Return Convert.ToDateTime(GetDoubleValue())
   End Function
   Function ToDecimal(ByVal provider As IFormatProvider) As Decimal Implements IConvertible.ToDecimal
      Return Convert.ToDecimal(GetDoubleValue())
   End Function
   Function ToDouble(ByVal provider As IFormatProvider) As Double Implements IConvertible.ToDouble
      Return GetDoubleValue()
   End Function
   Function ToInt16(ByVal provider As IFormatProvider) As Short Implements IConvertible.ToInt16
      Return Convert.ToInt16(GetDoubleValue())
   End Function
   Function ToInt32(ByVal provider As IFormatProvider) As Integer Implements IConvertible.ToInt32
      Return Convert.ToInt32(GetDoubleValue())
   End Function
   Function ToInt64(ByVal provider As IFormatProvider) As Long Implements IConvertible.ToInt64
      Return Convert.ToInt64(GetDoubleValue())
   End Function
   Function ToSByte(ByVal provider As IFormatProvider) As SByte Implements IConvertible.ToSByte
      Return Convert.ToSByte(GetDoubleValue())
   End Function
   Function ToSingle(ByVal provider As IFormatProvider) As Single Implements IConvertible.ToSingle
      Return Convert.ToSingle(GetDoubleValue())
   End Function
   Overloads Function ToString(ByVal provider As IFormatProvider) As String Implements IConvertible.ToString
      Return String.Format("({0}, {1})", x, y)
   End Function
   Function ToType(ByVal conversionType As Type, ByVal provider As IFormatProvider) As Object Implements IConvertible.ToType
      Return Convert.ChangeType(GetDoubleValue(), conversionType)
   End Function
   Function ToUInt16(ByVal provider As IFormatProvider) As UInt16 Implements IConvertible.ToUInt16
      Return Convert.ToUInt16(GetDoubleValue())
   End Function
   Function ToUInt32(ByVal provider As IFormatProvider) As UInt32 Implements IConvertible.ToUInt32
      Return Convert.ToUInt32(GetDoubleValue())
   End Function
   Function ToUInt64(ByVal provider As IFormatProvider) As UInt64 Implements IConvertible.ToUInt64
      Return Convert.ToUInt64(GetDoubleValue())
   End Function
End Class
Public Module Example
   Sub Main()
      Dim testComplex As New Complex(4, 7)
      WriteObjectInfo(testComplex)
      WriteObjectInfo(Convert.ToBoolean(testComplex))
      WriteObjectInfo(Convert.ToDecimal(testComplex))
      WriteObjectInfo(Convert.ToString(testComplex))
   End Sub
   Sub WriteObjectInfo(ByVal testObject As Object)
      Dim typeCode As TypeCode = Type.GetTypeCode(testObject.GetType())
      Select Case typeCode
         Case typeCode.Boolean
            Console.WriteLine("Boolean: {0}", testObject)
         Case typeCode.Double
            Console.WriteLine("Double: {0}", testObject)
         Case Else
            Console.WriteLine("{0}: {1}", typeCode.ToString(), testObject)
      End Select
   End Sub
End Module
      
       這個介面提供方法，可將實作型別實例的值轉換為具有對等值的 Common Language Runtime 類型。 Common Language Runtime 類型為
       
        Boolean
       
       、
       
        SByte
       
       、、
       
        Byte
       
       
        Int16
       
       、
       
        UInt16
       
       
        Int64
       
       
        Double
       
       
        UInt64
       
       
        UInt32
       
       
        Int32
       
       
        Decimal
       
       
        DateTime
       
       
        Single
       
       、、
       
        Char
       
       和 。
       
        String
       
      
      
       如果 Common Language Runtime 類型沒有有意義的轉換，則特定介面方法實作會擲回
       
        InvalidCastException
       
       。 例如，如果這個介面是在布林型別上實作，則方法的
       
        ToDateTime
       
       實作會擲回例外狀況，因為與布林類型沒有意義
       
        DateTime
       
       相等。
      
      
       Common Language Runtime 通常會透過
       
        Convert
       
       類別公開
       
        IConvertible
       
       介面。 Common Language Runtime 也會在明確介面實作中，在內部使用
       
        IConvertible
       
       介面，以簡化用來支援類別和基本 Common Language Runtime 類型轉換
       
        Convert
       
       的程式碼。
      
      
       除了
       
        IConvertible
       
       介面之外，.NET Framework還提供稱為類型轉換器的類別，以便將使用者定義資料類型轉換成其他資料類型。 如需詳細資訊，請參閱
       
        一般化類型轉換
       
       主題。
      
      
       給實施者的注意事項
      
      
       如果您實作
       
        IConvertible
       
       介面，如果
       
        Object
       
       參數是實作類型的實例，而且
       
        Type
       
       參數是 Common Language Runtime 類型，則方法會自動呼叫
       
        ChangeType(Object, Type)
       
       您的實作。
      
      
       大部分的轉換方法都有類型的
       
        IFormatProvider
       
       參數，代表目前文化特性 ()
       
        CurrentCulture
       
       或特定文化特性。 在大部分的情況下，
       
        IConvertible
       
       基底類型的實作會忽略此參數。 不過，您可以選擇是否要在程式碼中使用。