IConvertible Interface
Assembly: mscorlib (in mscorlib.dll)
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.
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; 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; } } } }
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
Windows 98, Windows Server 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
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.