IConvertible Interface

 

Defines methods that convert the value of the implementing reference or value type to a common language runtime type that has an equivalent value.

This API is not CLS-compliant.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

[CLSCompliantAttribute(false)]
[ComVisibleAttribute(true)]
public interface class IConvertible

NameDescription
System_CAPS_pubmethodGetTypeCode()

Returns the TypeCode for this instance.

System_CAPS_pubmethodToBoolean(IFormatProvider^)

Converts the value of this instance to an equivalent Boolean value using the specified culture-specific formatting information.

System_CAPS_pubmethodToByte(IFormatProvider^)

Converts the value of this instance to an equivalent 8-bit unsigned integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToChar(IFormatProvider^)

Converts the value of this instance to an equivalent Unicode character using the specified culture-specific formatting information.

System_CAPS_pubmethodToDateTime(IFormatProvider^)

Converts the value of this instance to an equivalent DateTime using the specified culture-specific formatting information.

System_CAPS_pubmethodToDecimal(IFormatProvider^)

Converts the value of this instance to an equivalent Decimal number using the specified culture-specific formatting information.

System_CAPS_pubmethodToDouble(IFormatProvider^)

Converts the value of this instance to an equivalent double-precision floating-point number using the specified culture-specific formatting information.

System_CAPS_pubmethodToInt16(IFormatProvider^)

Converts the value of this instance to an equivalent 16-bit signed integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToInt32(IFormatProvider^)

Converts the value of this instance to an equivalent 32-bit signed integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToInt64(IFormatProvider^)

Converts the value of this instance to an equivalent 64-bit signed integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToSByte(IFormatProvider^)

Converts the value of this instance to an equivalent 8-bit signed integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToSingle(IFormatProvider^)

Converts the value of this instance to an equivalent single-precision floating-point number using the specified culture-specific formatting information.

System_CAPS_pubmethodToString(IFormatProvider^)

Converts the value of this instance to an equivalent String using the specified culture-specific formatting information.

System_CAPS_pubmethodToType(Type^, IFormatProvider^)

Converts the value of this instance to an Object of the specified Type that has an equivalent value, using the specified culture-specific formatting information.

System_CAPS_pubmethodToUInt16(IFormatProvider^)

Converts the value of this instance to an equivalent 16-bit unsigned integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToUInt32(IFormatProvider^)

Converts the value of this instance to an equivalent 32-bit unsigned integer using the specified culture-specific formatting information.

System_CAPS_pubmethodToUInt64(IFormatProvider^)

Converts the value of this instance to an equivalent 64-bit unsigned integer using the specified culture-specific formatting information.

This interface provides methods to convert the value of an instance of an implementing type to a common language runtime type that has an equivalent value. The common language runtime types are Boolean, SByte, Byte, Int16, UInt16, Int32, UInt32, Int64, UInt64, Single, Double, Decimal, DateTime, Char, and String.

If there is no meaningful conversion to a common language runtime type, then a particular interface method implementation throws InvalidCastException. For example, if this interface is implemented on a Boolean type, the implementation of the ToDateTime method throws an exception because there is no meaningful DateTime equivalent to a Boolean type.

The common language runtime typically exposes the IConvertible interface through the Convert class. The common language runtime also uses the IConvertible interface internally, in explicit interface implementations, to simplify the code used to support conversions in the Convert class and basic common language runtime types.

In addition to the IConvertible interface, the .NET Framework provides classes called type converters for converting user-defined data types to other data types. For more information, see the Generalized Type Conversion topic.

Notes to Implementers:

If you implement the IConvertible interface, your implementation will be called automatically by the Convert::ChangeType method if the Object parameter is an instance of your implementing type and the Type parameter is a common language runtime type.

Most conversion methods have a parameter of type IFormatProvider that represents either the current culture (CultureInfo::CurrentCulture) or a specific culture. For the most part, the IConvertible implementations of the base types ignore this parameter. However, you can choose whether to use it in your code.

The following code sample demonstrates an implementation of IConvertible for a Complex number class, allowing it to be cast first as a Double and then calling the static Convert members on that Double.

#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 ) );
}

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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