IConvertible 接口
定义特定的方法,这些方法将实现引用或值类型的值转换为具有等效值的公共语言运行库类型。
**命名空间:**System
**程序集:**mscorlib(在 mscorlib.dll 中)
语法
声明
<ComVisibleAttribute(True)> _
<CLSCompliantAttribute(False)> _
Public Interface IConvertible
用法
Dim instance As IConvertible
[ComVisibleAttribute(true)]
[CLSCompliantAttribute(false)]
public interface IConvertible
[ComVisibleAttribute(true)]
[CLSCompliantAttribute(false)]
public interface class IConvertible
/** @attribute ComVisibleAttribute(true) */
/** @attribute CLSCompliantAttribute(false) */
public interface IConvertible
ComVisibleAttribute(true)
CLSCompliantAttribute(false)
public interface IConvertible
备注
此接口提供特定的方法,用以将实现类型的实例值转换为具有等效值的公共语言运行库类型。公共语言运行库类型包括 Boolean、SByte、Byte、Int16、UInt16、Int32、UInt32、Int64、UInt64、Single、Double、Decimal、DateTime、Char 和 String。
如果转换为公共语言运行库类型不具有任何意义,特定的接口方法实现则会引发 InvalidCastException。例如,如果该接口在 Boolean 类型上实现,由于没有与 Boolean 类型等效且具有意义的 DateTime,ToDateTime 方法的实现会引发异常。
通常,公共语言运行库通过 Convert 类公开 IConvertible 接口。在接口的显式实现中,公共语言运行库还在内部使用 IConvertible 接口来简化特定的代码,这些代码用于支持 Convert 类和基本公共语言运行库类型中的转换。
除了 IConvertible 接口之外,.NET Framework 还提供称作类型转换器的类来将用户定义的数据类型转换为其他数据类型。有关更多信息,请参见“通用类型转换”主题。
示例
下面的代码示例演示 Complex 数字类的 IConvertible 的一个实现,使该类首先可强制转换为 Double,然后调用该 Double 的静态 Convert 成员。
Imports System
Module Module1
Public Class Complex
Implements IConvertible
Private x As Double
Private y As Double
Public Sub New(ByVal x As Double, ByVal y As Double)
Me.x = x
Me.y = y
End Sub 'New
Public Function GetTypeCode() As TypeCode Implements IConvertible.GetTypeCode
Return TypeCode.Object
End Function
Function ToBoolean(ByVal provider As IFormatProvider) As Boolean Implements IConvertible.ToBoolean
If x <> 0 Or y <> 0 Then
Return True
Else
Return False
End If
End Function
Function GetDoubleValue() As Double
Return Math.Sqrt((x * x + y * y))
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 "( " + x.ToString() + " , " + y.ToString() + " )"
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
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
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;
else
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 "( " + x.ToString() + " , " + y.ToString() + " )";
}
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;
}
}
}
}
#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;
else
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 ) );
}
package ConsoleApplication2 ;
import System.*;
/// Class that implements IConvertible
class Complex implements IConvertible
{
private double x;
private double y;
public Complex(double x, double y)
{
this.x = x;
this.y = y;
} //Complex
public TypeCode GetTypeCode()
{
return TypeCode.Object;
} //GetTypeCode
public boolean ToBoolean(IFormatProvider provider)
{
if (x != 0.0 || y != 0.0) {
return true;
}
else {
return false;
}
} //ToBoolean
double GetDoubleValue()
{
return System.Math.Sqrt((x * x + y * y));
} //GetDoubleValue
public ubyte ToByte(IFormatProvider provider)
{
return Convert.ToByte(GetDoubleValue());
} //ToByte
public char ToChar(IFormatProvider provider)
{
return Convert.ToChar(GetDoubleValue());
} //ToChar
public DateTime ToDateTime(IFormatProvider provider)
{
return Convert.ToDateTime(GetDoubleValue());
} //ToDateTime
public System.Decimal ToDecimal(IFormatProvider provider)
{
return Convert.ToDecimal(GetDoubleValue());
} //ToDecimal
public double ToDouble(IFormatProvider provider)
{
return GetDoubleValue();
} //ToDouble
public short ToInt16(IFormatProvider provider)
{
return Convert.ToInt16(GetDoubleValue());
} //ToInt16
public int ToInt32(IFormatProvider provider)
{
return Convert.ToInt32(GetDoubleValue());
} //ToInt32
public long ToInt64(IFormatProvider provider)
{
return Convert.ToInt64(GetDoubleValue());
} //ToInt64
public byte ToSByte(IFormatProvider provider)
{
return Convert.ToSByte(GetDoubleValue());
} //ToSByte
public float ToSingle(IFormatProvider provider)
{
return Convert.ToSingle(GetDoubleValue());
} //ToSingle
public String ToString(IFormatProvider provider)
{
return "( " + System.Convert.ToString(x)
+ " , " + System.Convert.ToString(y)+ " )";
} //ToString
public Object ToType(Type conversionType, IFormatProvider provider)
{
return Convert.ChangeType(new Double(GetDoubleValue()),
conversionType);
} //ToType
public UInt16 ToUInt16(IFormatProvider provider)
{
return Convert.ToUInt16(GetDoubleValue());
} //ToUInt16
public UInt32 ToUInt32(IFormatProvider provider)
{
return Convert.ToUInt32(GetDoubleValue());
} //ToUInt32
public UInt64 ToUInt64(IFormatProvider provider)
{
return Convert.ToUInt64(GetDoubleValue());
} //ToUInt64
} //Complex
/// <summary>
/// Summary description for Class1.
/// </summary>
class Class1
{
public static void main(String[] args)
{
Complex testComplex = new Complex(4, 7);
WriteObjectInfo(testComplex);
WriteObjectInfo((System.Boolean)(Convert.ToBoolean(testComplex)));
WriteObjectInfo(Convert.ToDecimal(testComplex));
WriteObjectInfo(Convert.ToString(testComplex));
} //main
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;
}
} //WriteObjectInfo
} //Class1
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表,请参见系统要求。
版本信息
.NET Framework
受以下版本支持:2.0、1.1、1.0
.NET Compact Framework
受以下版本支持:2.0、1.0