Convert.ToChar Méthode

Définition

Convertit une valeur spécifiée en caractères Unicode.Converts a specified value to a Unicode character.

Surcharges

ToChar(String, IFormatProvider)

Convertit le premier caractère d'une chaîne spécifiée en caractère Unicode à l'aide des informations de mise en forme spécifiées propres à la culture.Converts the first character of a specified string to a Unicode character, using specified culture-specific formatting information.

ToChar(Object)

Convertit la valeur de l'objet spécifié en caractère Unicode.Converts the value of the specified object to a Unicode character.

ToChar(Object, IFormatProvider)

Convertit la valeur de l'objet spécifié en son caractère Unicode équivalent à l'aide des informations de mise en forme spécifiées propres à la culture.Converts the value of the specified object to its equivalent Unicode character, using the specified culture-specific formatting information.

ToChar(UInt64)

Convertit la valeur de l'entier non signé 64 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 64-bit unsigned integer to its equivalent Unicode character.

ToChar(UInt32)

Convertit la valeur de l'entier non signé 32 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 32-bit unsigned integer to its equivalent Unicode character.

ToChar(UInt16)

Convertit la valeur de l'entier non signé 16 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 16-bit unsigned integer to its equivalent Unicode character.

ToChar(String)

Convertit le premier caractère d'une chaîne spécifiée en caractère Unicode.Converts the first character of a specified string to a Unicode character.

ToChar(Single)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

ToChar(SByte)

Convertit la valeur de l'entier signé 8 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 8-bit signed integer to its equivalent Unicode character.

ToChar(Int64)

Convertit la valeur de l'entier signé 64 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 64-bit signed integer to its equivalent Unicode character.

ToChar(Int16)

Convertit la valeur de l'entier signé 16 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 16-bit signed integer to its equivalent Unicode character.

ToChar(Double)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

ToChar(Decimal)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

ToChar(DateTime)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

ToChar(Char)

Retourne la valeur du caractère Unicode spécifiée. Aucune conversion n'est effectuée.Returns the specified Unicode character value; no actual conversion is performed.

ToChar(Byte)

Convertit la valeur de l'entier non signé 8 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 8-bit unsigned integer to its equivalent Unicode character.

ToChar(Boolean)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

ToChar(Int32)

Convertit la valeur de l'entier signé 32 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 32-bit signed integer to its equivalent Unicode character.

ToChar(String, IFormatProvider)

Convertit le premier caractère d'une chaîne spécifiée en caractère Unicode à l'aide des informations de mise en forme spécifiées propres à la culture.Converts the first character of a specified string to a Unicode character, using specified culture-specific formatting information.

public:
 static char ToChar(System::String ^ value, IFormatProvider ^ provider);
public static char ToChar (string value, IFormatProvider provider);
static member ToChar : string * IFormatProvider -> char
Public Shared Function ToChar (value As String, provider As IFormatProvider) As Char

Paramètres

value
String

Chaîne de longueur 1 ou null.A string of length 1 or null.

provider
IFormatProvider

Objet qui fournit des informations de mise en forme propres à la culture.An object that supplies culture-specific formatting information. Ce paramètre est ignoré.This parameter is ignored.

Retours

Caractère Unicode qui est équivalent au premier et unique caractère de value.A Unicode character that is equivalent to the first and only character in value.

Exceptions

value a la valeur null.value is null.

La longueur de value n’est pas égale à 1.The length of value is not 1.

Exemples

L’exemple suivant convertit une représentation sous forme de chaîne d’une valeur Char avec la méthode ToChar, à l’aide d’un objet IFormatProvider qui affiche le type du fournisseur de format pour lequel il est appelé.The following example converts a string representation of a Char value with the ToChar method, using an IFormatProvider object that displays the type of the format provider for which it is called. L’exemple montre que le fournisseur de format n’est pas référencé.The example shows that the format provider is not referenced.

using namespace System;
using namespace System::Globalization;
ref class DummyProvider: public IFormatProvider
{
public:

   // Normally, GetFormat returns an object of the requested type
   // (usually itself) if it is able; otherwise, it returns Nothing. 
   virtual Object^ GetFormat( Type^ argType )
   {
      // Here, GetFormat displays the name of argType, after removing 
      // the namespace information. GetFormat always returns null.
      String^ argStr = argType->ToString();
      if ( argStr->Equals( "" ) )
            argStr = "Empty";

      argStr = argStr->Substring( argStr->LastIndexOf( '.' ) + 1 );
      Console::Write( "{0,-20}", argStr );
      return (Object^)0;
   }
};

int main()
{
   // Create an instance of IFormatProvider.
   DummyProvider^ provider = gcnew DummyProvider;
   String^ format = "{0,-17}{1,-17}{2}";

   // Convert these values using DummyProvider.
   String^ Int32A = "-252645135";
   String^ DoubleA = "61680.3855";
   String^ DayTimeA = "2001/9/11 13:45";
   String^ BoolA = "True";
   String^ StringA = "Qwerty";
   String^ CharA = "$";
   Console::WriteLine( "This example of selected "
   "Convert::To<Type>( String*, IFormatProvider* ) \nmethods "
   "generates the following output. The example displays the "
   "\nprovider type if the IFormatProvider is called." );
   Console::WriteLine( "\nNote: For the "
   "ToBoolean, ToString, and ToChar methods, the \n"
   "IFormatProvider object is not referenced." );

   // The format provider is called for the following conversions.
   Console::WriteLine();
   Console::WriteLine( format, "ToInt32", Int32A, Convert::ToInt32( Int32A, provider ) );
   Console::WriteLine( format, "ToDouble", DoubleA, Convert::ToDouble( DoubleA, provider ) );
   Console::WriteLine( format, "ToDateTime", DayTimeA, Convert::ToDateTime( DayTimeA, provider ) );

   // The format provider is not called for these conversions.
   Console::WriteLine();
   Console::WriteLine( format, "ToBoolean", BoolA, Convert::ToBoolean( BoolA, provider ) );
   Console::WriteLine( format, "ToString", StringA, Convert::ToString( StringA, provider ) );
   Console::WriteLine( format, "ToChar", CharA, Convert::ToChar( CharA, provider ) );
}

/*
This example of selected Convert::To<Type>( String*, IFormatProvider* )
methods generates the following output. The example displays the
provider type if the IFormatProvider is called.

Note: For the ToBoolean, ToString, and ToChar methods, the
IFormatProvider object is not referenced.

NumberFormatInfo    ToInt32          -252645135       -252645135
NumberFormatInfo    ToDouble         61680.3855       61680.3855
DateTimeFormatInfo  ToDateTime       2001/9/11 13:45  9/11/2001 1:45:00 PM

ToBoolean        True             True
ToString         Qwerty           Qwerty
ToChar           $                $
*/
using System;
using System.Globalization;

public class DummyProvider : IFormatProvider
{
    // Normally, GetFormat returns an object of the requested type
    // (usually itself) if it is able; otherwise, it returns Nothing. 
    public object GetFormat(Type argType)
    {
        // Here, GetFormat displays the name of argType, after removing 
        // the namespace information. GetFormat always returns null.
        string argStr = argType.ToString( );
        if( argStr == "" ) 
            argStr = "Empty";
        argStr = argStr.Substring( argStr.LastIndexOf( '.' ) + 1 );

        Console.Write( "{0,-20}", argStr );
        return null;
    }
}

class ConvertNonNumericProviderDemo
{
    public static void Main( )
    {
        // Create an instance of IFormatProvider.
        DummyProvider provider = new DummyProvider( );
        string format   = "{0,-17}{1,-17}{2}";

        // Convert these values using DummyProvider.
        string Int32A   = "-252645135";
        string DoubleA  = "61680.3855";
        string DayTimeA = "2001/9/11 13:45";

        string BoolA    = "True";
        string StringA  = "Qwerty";
        string CharA    = "$";

        Console.WriteLine( "This example of selected " +
            "Convert.To<Type>( String, IFormatProvider ) \nmethods " +
            "generates the following output. The example displays " +
            "the \nprovider type if the IFormatProvider is called." );
        Console.WriteLine( "\nNote: For the " +
            "ToBoolean, ToString, and ToChar methods, the \n" +
            "IFormatProvider object is not referenced." );

        // The format provider is called for the following conversions.
        Console.WriteLine( );
        Console.WriteLine( format, "ToInt32", Int32A, 
            Convert.ToInt32( Int32A, provider ) );
        Console.WriteLine( format, "ToDouble", DoubleA, 
            Convert.ToDouble( DoubleA, provider ) );
        Console.WriteLine( format, "ToDateTime", DayTimeA, 
            Convert.ToDateTime( DayTimeA, provider ) );

        // The format provider is not called for these conversions.
        Console.WriteLine( );
        Console.WriteLine( format, "ToBoolean", BoolA, 
            Convert.ToBoolean( BoolA, provider ) );
        Console.WriteLine( format, "ToString", StringA, 
            Convert.ToString( StringA, provider ) );
        Console.WriteLine( format, "ToChar", CharA, 
            Convert.ToChar( CharA, provider ) );
    }
}

/*
This example of selected Convert.To<Type>( String, IFormatProvider )
methods generates the following output. The example displays the
provider type if the IFormatProvider is called.

Note: For the ToBoolean, ToString, and ToChar methods, the
IFormatProvider object is not referenced.

NumberFormatInfo    ToInt32          -252645135       -252645135
NumberFormatInfo    ToDouble         61680.3855       61680.3855
DateTimeFormatInfo  ToDateTime       2001/9/11 13:45  9/11/2001 1:45:00 PM

ToBoolean        True             True
ToString         Qwerty           Qwerty
ToChar           $                $
*/ 
Imports System.Globalization

Public Class DummyProvider
    Implements IFormatProvider

    ' Normally, GetFormat returns an object of the requested type
    ' (usually itself) if it is able; otherwise, it returns Nothing. 
    Public Function GetFormat( argType As Type ) As Object _
        Implements IFormatProvider.GetFormat

        ' Here, GetFormat displays the name of argType, after removing 
        ' the namespace information. GetFormat always returns Nothing.
        Dim argStr  As String = argType.ToString( )
        If argStr = "" Then argStr = "Empty"
        argStr = argStr.Substring( argStr.LastIndexOf( "."c ) + 1 )

        Console.Write( "{0,-20}", argStr )
        Return Nothing

    End Function 
End Class

Module ConvertNonNumericProviderDemo

    Sub Main( )

        ' Create an instance of IFormatProvider.
        Dim provider    As New DummyProvider( )
        Dim format      As String   = "{0,-17}{1,-17}{2}"

        ' Convert these values using DummyProvider.
        Dim Int32A      As String   = "-252645135"   
        Dim DoubleA     As String   = "61680.3855"
        Dim DayTimeA    As String   = "2001/9/11 13:45"

        Dim BoolA       As String   = "True"
        Dim StringA     As String   = "Qwerty"
        Dim CharA       As String   = "$"

        Console.WriteLine( "This example of selected " & _
            "Convert.To<Type>( String, IFormatProvider ) " & vbCrLf & _
            "methods generates the following output. The example " & _
            "displays the " & vbCrLf & "provider type if the " & _
            "IFormatProvider is called." )
        Console.WriteLine( vbCrLf & _
            "Note: For the ToBoolean, ToString, and ToChar " & _
            "methods, the " & vbCrLf & "IFormatProvider object " & _
            "is not referenced." )

        ' The format provider is called for the following conversions.
        Console.WriteLine( )
        Console.WriteLine( format, "ToInt32", Int32A, _
            Convert.ToInt32( Int32A, provider ) )
        Console.WriteLine( format, "ToDouble", DoubleA, _
            Convert.ToDouble( DoubleA, provider ) )
        Console.WriteLine( format, "ToDateTime", DayTimeA, _
            Convert.ToDateTime( DayTimeA, provider ) )

        ' The format provider is not called for these conversions.
        Console.WriteLine( )
        Console.WriteLine( format, "ToBoolean", BoolA, _
            Convert.ToBoolean( BoolA, provider ) )
        Console.WriteLine( format, "ToString", StringA, _
            Convert.ToString( StringA, provider ) )
        Console.WriteLine( format, "ToChar", CharA, _
            Convert.ToChar( CharA, provider ) )

    End Sub
End Module

' This example of selected Convert.To<Type>( String, IFormatProvider )
' methods generates the following output. The example displays the
' provider type if the IFormatProvider is called.
'
' Note: For the ToBoolean, ToString, and ToChar methods, the
' IFormatProvider object is not referenced.
' 
' NumberFormatInfo    ToInt32          -252645135       -252645135
' NumberFormatInfo    ToDouble         61680.3855       61680.3855
' DateTimeFormatInfo  ToDateTime       2001/9/11 13:45  9/11/2001 1:45:00 PM
' 
' ToBoolean        True             True
' ToString         Qwerty           Qwerty
' ToChar           $                $

Remarques

value doit être une chaîne qui contient un seul caractère.value must be a string that contains a single character.

Si vous préférez ne pas gérer une exception en cas d’échec de la conversion, vous pouvez appeler la méthode Char.TryParse à la place.If you prefer not to handle an exception if the conversion fails, you can call the Char.TryParse method instead. Elle retourne une valeur Boolean qui indique si la conversion a réussi ou a échoué.It returns a Boolean value that indicates whether the conversion succeeded or failed.

ToChar(Object)

Convertit la valeur de l'objet spécifié en caractère Unicode.Converts the value of the specified object to a Unicode character.

public:
 static char ToChar(System::Object ^ value);
public static char ToChar (object value);
static member ToChar : obj -> char
Public Shared Function ToChar (value As Object) As Char

Paramètres

value
Object

Objet qui implémente l'interface IConvertible .An object that implements the IConvertible interface.

Retours

Caractère Unicode équivalent à value, ou MinValue si value est null.A Unicode character that is equivalent to value, or MinValue if value is null.

Exceptions

value est une chaîne null.value is a null string.

value n’implémente pas l’interface IConvertible .value does not implement the IConvertible interface.

-ou--or- La conversion de value en un Char n’est pas prise en charge.The conversion of value to a Char is not supported.

value est inférieur à MinValue ou supérieur à MaxValue.value is less than MinValue or greater than MaxValue.

Exemples

L’exemple suivant tente de convertir chaque élément d’un tableau d’objets en valeur Char.The following example attempts to convert each element in an object array to a Char value.

object[] values = { 'r', "s", "word", (byte) 83, 77, 109324, 335812911, 
                    new DateTime(2009, 3, 10), (uint) 1934, 
                    (sbyte) -17, 169.34, 175.6m, null };
char result;

foreach (object value in values)
{
   try {
      result = Convert.ToChar(value);
      Console.WriteLine("The {0} value {1} converts to {2}.", 
                        value.GetType().Name, value, result);
   }
   catch (FormatException e) {
      Console.WriteLine(e.Message);
   }
   catch (InvalidCastException) {
      Console.WriteLine("Conversion of the {0} value {1} to a Char is not supported.",
                        value.GetType().Name, value);
   }
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the Char data type.",
                        value.GetType().Name, value);
   }
   catch (NullReferenceException) {
      Console.WriteLine("Cannot convert a null reference to a Char.");
   }
}
// The example displays the following output:
//       The Char value r converts to r.
//       The String value s converts to s.
//       String must be exactly one character long.
//       The Byte value 83 converts to S.
//       The Int32 value 77 converts to M.
//       The Int32 value 109324 is outside the range of the Char data type.
//       The Int32 value 335812911 is outside the range of the Char data type.
//       Conversion of the DateTime value 3/10/2009 12:00:00 AM to a Char is not supported.
//       The UInt32 value 1934 converts to ?.
//       The SByte value -17 is outside the range of the Char data type.
//       Conversion of the Double value 169.34 to a Char is not supported.
//       Conversion of the Decimal value 175.6 to a Char is not supported.
//       Cannot convert a null reference to a Char.      
Dim values() As Object = { "r"c, "s", "word", CByte(83), 77, 109324, _
                           335812911, #3/10/2009#, CUInt(1934), _ 
                           CSByte(-17), 169.34, 175.6d, Nothing }
Dim result As Char

For Each value As Object In values
   Try
      result = Convert.ToChar(value)
      Console.WriteLine("The {0} value {1} converts to {2}.", _ 
                        value.GetType().Name, value, result)
   Catch e As FormatException
      Console.WriteLine(e.Message)
   Catch e As InvalidCastException
      Console.WriteLine("Conversion of the {0} value {1} to a Char is not supported.", _
                        value.GetType().Name, value)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Char data type.", _
                        value.GetType().Name, value)
   Catch e As NullReferenceException
      Console.WriteLine("Cannot convert a null reference to a Char.")
   End Try
Next
' The example displays the following output:
'       The Char value r converts to r.
'       The String value s converts to s.
'       String must be exactly one character long.
'       The Byte value 83 converts to S.
'       The Int32 value 77 converts to M.
'       The Int32 value 109324 is outside the range of the Char data type.
'       The Int32 value 335812911 is outside the range of the Char data type.
'       Conversion of the DateTime value 3/10/2009 12:00:00 AM to a Char is not supported.
'       The UInt32 value 1934 converts to ?.
'       The SByte value -17 is outside the range of the Char data type.
'       Conversion of the Double value 169.34 to a Char is not supported.
'       Conversion of the Decimal value 175.6 to a Char is not supported.
'       Cannot convert a null reference to a Char.      

Remarques

Si value n’est pas null, cette méthode encapsule un appel à l’implémentation IConvertible.ToChar du type sous-jacent de value.If value is not null, this method wraps a call to the IConvertible.ToChar implementation of the underlying type of value.

ToChar(Object, IFormatProvider)

Convertit la valeur de l'objet spécifié en son caractère Unicode équivalent à l'aide des informations de mise en forme spécifiées propres à la culture.Converts the value of the specified object to its equivalent Unicode character, using the specified culture-specific formatting information.

public:
 static char ToChar(System::Object ^ value, IFormatProvider ^ provider);
public static char ToChar (object value, IFormatProvider provider);
static member ToChar : obj * IFormatProvider -> char
Public Shared Function ToChar (value As Object, provider As IFormatProvider) As Char

Paramètres

value
Object

Objet qui implémente l'interface IConvertible .An object that implements the IConvertible interface.

provider
IFormatProvider

Objet qui fournit des informations de mise en forme propres à la culture.An object that supplies culture-specific formatting information.

Retours

Caractère Unicode équivalent à value, ou MinValue si value est null.A Unicode character that is equivalent to value, or MinValue if value is null.

Exceptions

value est une chaîne null.value is a null string.

value n’implémente pas l’interface IConvertible .value does not implement the IConvertible interface.

-ou--or- La conversion de value en un Char n’est pas prise en charge.The conversion of value to a Char is not supported.

value est inférieur à MinValue ou supérieur à MaxValue.value is less than MinValue or greater than MaxValue.

Exemples

L’exemple suivant définit une classe qui implémente IConvertible et une classe qui implémente IFormatProvider.The following example defines a class that implements IConvertible and a class that implements IFormatProvider. Les objets de la classe qui implémente IConvertible contenir un tableau de valeurs de Double.Objects of the class that implements IConvertible hold an array of Double values. Un objet de chaque classe est passé à la méthode ToChar.An object of each class is passed to the ToChar method. Cette méthode retourne un caractère dont la valeur Unicode est la moyenne du tableau de valeurs de Double, à l’aide de l’objet qui implémente IFormatProvider pour déterminer comment calculer la moyenne.This method returns a character whose Unicode value is the average of the array of Double values, using the object that implements IFormatProvider to determine how to calculate the average.

using namespace System;
using namespace System::Collections;

// Define the types of averaging available in the class 
// implementing IConvertible.
public enum class AverageType : short
{
   None = 0,
   GeometricMean = 1,
   ArithmeticMean = 2,
   Median = 3
};


// Pass an instance of this class to methods that require an 
// IFormatProvider. The class instance determines the type of 
// average to calculate.
ref class AverageInfo: public IFormatProvider
{
protected:
   AverageType AvgType;

public:

   // Specify the type of averaging in the constructor.
   AverageInfo( AverageType avgType )
   {
      this->AvgType = avgType;
   }


   // This method returns a reference to the containing object 
   // if an object of AverageInfo type is requested. 
   virtual Object^ GetFormat( Type^ argType )
   {
      if ( argType == AverageInfo::typeid)
            return this;
      else
            return (Object^)0;
   }


   property AverageType TypeOfAverage 
   {

      // Use this property to set or get the type of averaging.
      AverageType get()
      {
         return this->AvgType;
      }

      void set( AverageType value )
      {
         this->AvgType = value;
      }

   }

};


// This class encapsulates an array of double values and implements 
// the IConvertible interface. Most of the IConvertible methods 
// return an average of the array elements in one of three types: 
// arithmetic mean, geometric mean, or median. 
ref class DataSet: public IConvertible
{
private:
   static Object^ null = nullptr;

protected:
   ArrayList^ data;
   AverageInfo^ defaultProvider;

   // This method unboxes a boxed double.
   double UnBoxDouble( Object^ obj )
   {
      return  *static_cast<double^>(obj);
   }


public:

   // Construct the object and add an initial list of values.
   // Create a default format provider.
   DataSet( ... array<Double>^values )
   {
      data = gcnew ArrayList( (Array^)values );
      defaultProvider = gcnew AverageInfo( AverageType::ArithmeticMean );
   }


   // Add additional values with this method.
   int Add( double value )
   {
      data->Add( value );
      return data->Count;
   }


   property double Item[ int ]
   {

      // Get, set, and add values with this indexer property.
      double get( int index )
      {
         if ( index >= 0 && index < data->Count )
                  return UnBoxDouble( data[ index ] );
         else
                  throw gcnew InvalidOperationException( "[DataSet.get] Index out of range." );
      }

      void set( int index, double value )
      {
         if ( index >= 0 && index < data->Count )
                  data[ index ] = value;
         else
         if ( index == data->Count )
                  data->Add( value );
         else
                  throw gcnew InvalidOperationException( "[DataSet.set] Index out of range." );
      }

   }

   property int Count 
   {

      // This property returns the number of elements in the object.
      int get()
      {
         return data->Count;
      }

   }

protected:

   // This method calculates the average of the object's elements.
   double Average( AverageType avgType )
   {
      double SumProd;
      if ( data->Count == 0 )
            return 0.0;

      switch ( avgType )
      {
         case AverageType::GeometricMean:
            SumProd = 1.0;
            for ( int Index = 0; Index < data->Count; Index++ )
               SumProd *= UnBoxDouble( data[ Index ] );
            
            // This calculation will not fail with negative 
            // elements.
            return Math::Sign( SumProd ) * Math::Pow( Math::Abs( SumProd ), 1.0 / data->Count );

         case AverageType::ArithmeticMean:
            SumProd = 0.0;
            for ( int Index = 0; Index < data->Count; Index++ )
               SumProd += UnBoxDouble( data[ Index ] );
            return SumProd / data->Count;

         case AverageType::Median:
            if ( data->Count % 2 == 0 )
                        return (UnBoxDouble( data[ data->Count / 2 ] ) + UnBoxDouble( data[ data->Count / 2 - 1 ] )) / 2.0;
            else
                        return UnBoxDouble( data[ data->Count / 2 ] );

         default:
            return 0.0;
      }
   }


   // Get the AverageInfo object from the caller's format provider,
   // or use the local default.
   AverageInfo^ GetAverageInfo( IFormatProvider^ provider )
   {
      AverageInfo^ avgInfo = nullptr;
      if ( provider != nullptr )
            avgInfo = static_cast<AverageInfo^>(provider->GetFormat( AverageInfo::typeid ));

      if ( avgInfo == nullptr )
            return defaultProvider;
      else
            return avgInfo;
   }


   // Calculate the average and limit the range.
   double CalcNLimitAverage( double min, double max, IFormatProvider^ provider )
   {
      
      // Get the format provider and calculate the average.
      AverageInfo^ avgInfo = GetAverageInfo( provider );
      double avg = Average( avgInfo->TypeOfAverage );
      
      // Limit the range, based on the minimum and maximum values 
      // for the type.
      return avg > max ? max : avg < min ? min : avg;
   }


public:

   // The following elements are required by IConvertible.
   // None of these conversion functions throw exceptions. When
   // the data is out of range for the type, the appropriate
   // MinValue or MaxValue is used.
   virtual TypeCode GetTypeCode()
   {
      return TypeCode::Object;
   }

   virtual bool ToBoolean( IFormatProvider^ provider )
   {
      
      // ToBoolean is false if the dataset is empty.
      if ( data->Count <= 0 )
            return false;
      // For median averaging, ToBoolean is true if any 
      // non-discarded elements are nonzero.
      else
      
      // For median averaging, ToBoolean is true if any 
      // non-discarded elements are nonzero.
      if ( AverageType::Median == GetAverageInfo( provider )->TypeOfAverage )
      {
         if ( data->Count % 2 == 0 )
                  return (UnBoxDouble( data[ data->Count / 2 ] ) != 0.0 || UnBoxDouble( data[ data->Count / 2 - 1 ] ) != 0.0);
         else
                  return UnBoxDouble( data[ data->Count / 2 ] ) != 0.0;
      }
      // For arithmetic or geometric mean averaging, ToBoolean is 
      // true if any element of the dataset is nonzero.  
      else
      {
         for ( int Index = 0; Index < data->Count; Index++ )
            if ( UnBoxDouble( data[ Index ] ) != 0.0 )
                        return true;
         return false;
      }
   }

   virtual Byte ToByte( IFormatProvider^ provider )
   {
      return Convert::ToByte( CalcNLimitAverage( Byte::MinValue, Byte::MaxValue, provider ) );
   }

   virtual Char ToChar( IFormatProvider^ provider )
   {
      return Convert::ToChar( Convert::ToUInt16( CalcNLimitAverage( Char::MinValue, Char::MaxValue, provider ) ) );
   }


   // Convert to DateTime by adding the calculated average as 
   // seconds to the current date and time. A valid DateTime is 
   // always returned.
   virtual DateTime ToDateTime( IFormatProvider^ provider )
   {
      double seconds = Average( GetAverageInfo( provider )->TypeOfAverage );
      try
      {
         return DateTime::Now.AddSeconds( seconds );
      }
      catch ( ArgumentOutOfRangeException^ ) 
      {
         return seconds < 0.0 ? DateTime::MinValue : DateTime::MaxValue;
      }

   }

   virtual Decimal ToDecimal( IFormatProvider^ provider )
   {
      
      // The Double conversion rounds Decimal.MinValue and 
      // Decimal.MaxValue to invalid Decimal values, so the 
      // following limits must be used.
      return Convert::ToDecimal( CalcNLimitAverage(  -79228162514264330000000000000.0, 79228162514264330000000000000.0, provider ) );
   }

   virtual double ToDouble( IFormatProvider^ provider )
   {
      return Average( GetAverageInfo( provider )->TypeOfAverage );
   }

   virtual short ToInt16( IFormatProvider^ provider )
   {
      return Convert::ToInt16( CalcNLimitAverage( Int16::MinValue, Int16::MaxValue, provider ) );
   }

   virtual int ToInt32( IFormatProvider^ provider )
   {
      return Convert::ToInt32( CalcNLimitAverage( Int32::MinValue, Int32::MaxValue, provider ) );
   }

   virtual __int64 ToInt64( IFormatProvider^ provider )
   {
      
      // The Double conversion rounds Int64.MinValue and 
      // Int64.MaxValue to invalid Int64 values, so the following 
      // limits must be used.
      return Convert::ToInt64( CalcNLimitAverage(  -9223372036854775000, 9223372036854775000, provider ) );
   }

   virtual signed char ToSByte( IFormatProvider^ provider )
   {
      return Convert::ToSByte( CalcNLimitAverage( SByte::MinValue, SByte::MaxValue, provider ) );
   }

   virtual float ToSingle( IFormatProvider^ provider )
   {
      return Convert::ToSingle( CalcNLimitAverage( Single::MinValue, Single::MaxValue, provider ) );
   }

   virtual UInt16 ToUInt16( IFormatProvider^ provider )
   {
      return Convert::ToUInt16( CalcNLimitAverage( UInt16::MinValue, UInt16::MaxValue, provider ) );
   }

   virtual UInt32 ToUInt32( IFormatProvider^ provider )
   {
      return Convert::ToUInt32( CalcNLimitAverage( UInt32::MinValue, UInt32::MaxValue, provider ) );
   }

   virtual UInt64 ToUInt64( IFormatProvider^ provider )
   {
      
      // The Double conversion rounds UInt64.MaxValue to an invalid
      // UInt64 value, so the following limit must be used.
      return Convert::ToUInt64( CalcNLimitAverage( 0, 18446744073709550000.0, provider ) );
   }

   virtual Object^ ToType( Type^ conversionType, IFormatProvider^ provider )
   {
      return Convert::ChangeType( Average( GetAverageInfo( provider )->TypeOfAverage ), conversionType );
   }

   virtual String^ ToString( IFormatProvider^ provider )
   {
      AverageType avgType = GetAverageInfo( provider )->TypeOfAverage;
      return String::Format( "( {0}: {1:G10} )", avgType, Average( avgType ) );
   }

};


// Display a DataSet with three different format providers.
void DisplayDataSet( DataSet^ ds )
{
   IFormatProvider^ null = nullptr;
   String^ fmt = "{0,-12}{1,20}{2,20}{3,20}";
   AverageInfo^ median = gcnew AverageInfo( AverageType::Median );
   AverageInfo^ geMean = gcnew AverageInfo( AverageType::GeometricMean );
   
   // Display the dataset elements.
   if ( ds->Count > 0 )
   {
      Console::Write( "\nDataSet: [{0}", ds->Item[ 0 ] );
      for ( int iX = 1; iX < ds->Count; iX++ )
         Console::Write( ", {0}", ds->Item[ iX ] );
      Console::WriteLine( "]\n" );
   }

   Console::WriteLine( fmt, "Convert::", "Default", "Geometric Mean", "Median" );
   Console::WriteLine( fmt, "---------", "-------", "--------------", "------" );
   Console::WriteLine( fmt, "ToBoolean", Convert::ToBoolean( ds, null ), Convert::ToBoolean( ds, geMean ), Convert::ToBoolean( ds, median ) );
   Console::WriteLine( fmt, "ToByte", Convert::ToByte( ds, null ), Convert::ToByte( ds, geMean ), Convert::ToByte( ds, median ) );
   Console::WriteLine( fmt, "ToChar", Convert::ToChar( ds, null ), Convert::ToChar( ds, geMean ), Convert::ToChar( ds, median ) );
   Console::WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}"
   "{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}", "ToDateTime", Convert::ToDateTime( ds, null ), Convert::ToDateTime( ds, geMean ), Convert::ToDateTime( ds, median ) );
   Console::WriteLine( fmt, "ToDecimal", Convert::ToDecimal( ds, null ), Convert::ToDecimal( ds, geMean ), Convert::ToDecimal( ds, median ) );
   Console::WriteLine( fmt, "ToDouble", Convert::ToDouble( ds, null ), Convert::ToDouble( ds, geMean ), Convert::ToDouble( ds, median ) );
   Console::WriteLine( fmt, "ToInt16", Convert::ToInt16( ds, null ), Convert::ToInt16( ds, geMean ), Convert::ToInt16( ds, median ) );
   Console::WriteLine( fmt, "ToInt32", Convert::ToInt32( ds, null ), Convert::ToInt32( ds, geMean ), Convert::ToInt32( ds, median ) );
   Console::WriteLine( fmt, "ToInt64", Convert::ToInt64( ds, null ), Convert::ToInt64( ds, geMean ), Convert::ToInt64( ds, median ) );
   Console::WriteLine( fmt, "ToSByte", Convert::ToSByte( ds, null ), Convert::ToSByte( ds, geMean ), Convert::ToSByte( ds, median ) );
   Console::WriteLine( fmt, "ToSingle", Convert::ToSingle( ds, null ), Convert::ToSingle( ds, geMean ), Convert::ToSingle( ds, median ) );
   Console::WriteLine( fmt, "ToUInt16", Convert::ToUInt16( ds, null ), Convert::ToUInt16( ds, geMean ), Convert::ToUInt16( ds, median ) );
   Console::WriteLine( fmt, "ToUInt32", Convert::ToUInt32( ds, null ), Convert::ToUInt32( ds, geMean ), Convert::ToUInt32( ds, median ) );
   Console::WriteLine( fmt, "ToUInt64", Convert::ToUInt64( ds, null ), Convert::ToUInt64( ds, geMean ), Convert::ToUInt64( ds, median ) );
}

int main()
{
   Console::WriteLine( "This example of the "
   "Convert::To<Type>( Object*, IFormatProvider* ) methods "
   "\ngenerates the following output. The example "
   "displays the values \nreturned by the methods, "
   "using several IFormatProvider objects.\n" );
   
   // To call a [ParamArray] method in C++, you cannot just
   // list the parameters, you need to build an array.
   array<Double>^dataElem = gcnew array<Double>(6);
   dataElem[ 0 ] = 10.5;
   dataElem[ 1 ] = 22.2;
   dataElem[ 2 ] = 45.9;
   dataElem[ 3 ] = 88.7;
   dataElem[ 4 ] = 156.05;
   dataElem[ 5 ] = 297.6;
   DataSet^ ds1 = gcnew DataSet( dataElem );
   DisplayDataSet( ds1 );
   dataElem = gcnew array<Double>(5);
   dataElem[ 0 ] = 359999.95;
   dataElem[ 1 ] = 425000;
   dataElem[ 2 ] = 499999.5;
   dataElem[ 3 ] = 775000;
   dataElem[ 4 ] = 1695000;
   DataSet^ ds2 = gcnew DataSet( dataElem );
   DisplayDataSet( ds2 );
}

/*
This example of the Convert::To<Type>( Object*, IFormatProvider* ) methods
generates the following output. The example displays the values
returned by the methods, using several IFormatProvider objects.

DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]

Convert::                Default      Geometric Mean              Median
---------                -------      --------------              ------
ToBoolean                   True                True                True
ToByte                       103                  59                  67
ToChar                         g                   ;                   C
ToDateTime   2003-05-13 15:30:23 2003-05-13 15:29:39 2003-05-13 15:29:47
ToDecimal       103.491666666667    59.4332135445164                67.3
ToDouble        103.491666666667    59.4332135445164                67.3
ToInt16                      103                  59                  67
ToInt32                      103                  59                  67
ToInt64                      103                  59                  67
ToSByte                      103                  59                  67
ToSingle                103.4917            59.43321                67.3
ToUInt16                     103                  59                  67
ToUInt32                     103                  59                  67
ToUInt64                     103                  59                  67

DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]

Convert::                Default      Geometric Mean              Median
---------                -------      --------------              ------
ToBoolean                   True                True                True
ToByte                       255                 255                 255
ToChar                         ?                   ?                   ?
ToDateTime   2003-05-22 08:05:19 2003-05-20 22:54:57 2003-05-19 10:21:59
ToDecimal              750999.89    631577.237188435            499999.5
ToDouble               750999.89    631577.237188435            499999.5
ToInt16                    32767               32767               32767
ToInt32                   751000              631577              500000
ToInt64                   751000              631577              500000
ToSByte                      127                 127                 127
ToSingle                750999.9            631577.3            499999.5
ToUInt16                   65535               65535               65535
ToUInt32                  751000              631577              500000
ToUInt64                  751000              631577              500000
*/
using System;
using System.Collections;

// Define the types of averaging available in the class 
// implementing IConvertible.
public enum AverageType : short
{
    None = 0,
    GeometricMean = 1,
    ArithmeticMean = 2,
    Median = 3
};

// Pass an instance of this class to methods that require an 
// IFormatProvider. The class instance determines the type of 
// average to calculate.
public class AverageInfo : IFormatProvider
{
    protected AverageType AvgType;

    // Specify the type of averaging in the constructor.
    public AverageInfo( AverageType avgType )
    {
        this.AvgType = avgType;
    }

    // This method returns a reference to the containing object 
    // if an object of AverageInfo type is requested. 
    public object GetFormat( Type argType )
    {
        if ( argType == typeof( AverageInfo ) )
            return this;
        else
            return null;
    }

    // Use this property to set or get the type of averaging.
    public AverageType TypeOfAverage        
    {
        get { return this.AvgType; }
        set { this.AvgType = value; }
    }
}

// This class encapsulates an array of double values and implements 
// the IConvertible interface. Most of the IConvertible methods 
// return an average of the array elements in one of three types: 
// arithmetic mean, geometric mean, or median. 
public class DataSet : IConvertible
{
    protected ArrayList     data;
    protected AverageInfo   defaultProvider;
        
    // Construct the object and add an initial list of values.
    // Create a default format provider.
    public DataSet( params double[ ] values )
    {
        data = new ArrayList( values );
        defaultProvider = 
            new AverageInfo( AverageType.ArithmeticMean );
    }
        
    // Add additional values with this method.
    public int Add( double value )
    {
        data.Add( value );
        return data.Count;
    }
        
    // Get, set, and add values with this indexer property.
    public double this[ int index ]        
    {
        get
        {
            if( index >= 0 && index < data.Count )
                return (double)data[ index ];
            else
                throw new InvalidOperationException(
                    "[DataSet.get] Index out of range." );
        }
        set
        {
            if( index >= 0 && index < data.Count )
                data[ index ] = value;

            else if( index == data.Count )
                data.Add( value );
            else
                throw new InvalidOperationException(
                    "[DataSet.set] Index out of range." );
        }
    }
        
    // This property returns the number of elements in the object.
    public int Count        
    {
        get { return data.Count; }
    }

    // This method calculates the average of the object's elements.
    protected double Average( AverageType avgType )
    {
        double  SumProd;

        if( data.Count == 0 ) 
            return 0.0;

        switch( avgType )
        {
            case AverageType.GeometricMean:

                SumProd = 1.0;
                for( int Index = 0; Index < data.Count; Index++ )
                    SumProd *= (double)data[ Index ];
                
                // This calculation will not fail with negative 
                // elements.
                return Math.Sign( SumProd ) * Math.Pow( 
                    Math.Abs( SumProd ), 1.0 / data.Count );

            case AverageType.ArithmeticMean:

                SumProd = 0.0;
                for( int Index = 0; Index < data.Count; Index++ )
                    SumProd += (double)data[ Index ];

                return SumProd / data.Count;

            case AverageType.Median:

                if( data.Count % 2 == 0 )
                    return ( (double)data[ data.Count / 2 ] + 
                        (double)data[ data.Count / 2 - 1 ] ) / 2.0;
                else
                    return (double)data[ data.Count / 2 ];

            default:
                return 0.0;
        }
    }

    // Get the AverageInfo object from the caller's format provider,
    // or use the local default.
    protected AverageInfo GetAverageInfo( IFormatProvider provider )
    {
        AverageInfo avgInfo = null;

        if( provider != null )
            avgInfo = (AverageInfo)provider.GetFormat( 
                typeof( AverageInfo ) );

        if ( avgInfo == null )
            return defaultProvider;
        else
            return avgInfo;
    }

    // Calculate the average and limit the range.
    protected double CalcNLimitAverage( double min, double max, 
        IFormatProvider provider )
    {
        // Get the format provider and calculate the average.
        AverageInfo avgInfo = GetAverageInfo( provider );
        double avg = Average( avgInfo.TypeOfAverage );

        // Limit the range, based on the minimum and maximum values 
        // for the type.
        return avg > max ? max : avg < min ? min : avg;
    }

    // The following elements are required by IConvertible.

    // None of these conversion functions throw exceptions. When
    // the data is out of range for the type, the appropriate
    // MinValue or MaxValue is used.
    public TypeCode GetTypeCode( )
    {
        return TypeCode.Object;
    }

    public bool ToBoolean( IFormatProvider provider )
    {
        // ToBoolean is false if the dataset is empty.
        if( data.Count <= 0 )
        {
            return false;
        }

        // For median averaging, ToBoolean is true if any 
        // non-discarded elements are nonzero.
        else if( AverageType.Median == 
            GetAverageInfo( provider ).TypeOfAverage )
        {
            if (data.Count % 2 == 0 )
                return ( (double)data[ data.Count / 2 ] != 0.0 || 
                    (double)data[ data.Count / 2 - 1 ] != 0.0 );
            else
                return (double)data[ data.Count / 2 ] != 0.0;
        }

        // For arithmetic or geometric mean averaging, ToBoolean is 
        // true if any element of the dataset is nonzero.  
        else
        {
            for( int Index = 0; Index < data.Count; Index++ )
                if( (double)data[ Index ] != 0.0 ) 
                    return true;
            return false;
        }
    }

    public byte ToByte( IFormatProvider provider )
    {
        return Convert.ToByte( CalcNLimitAverage( 
            Byte.MinValue, Byte.MaxValue, provider ) );
    }

    public char ToChar( IFormatProvider provider )
    {
        return Convert.ToChar( Convert.ToUInt16( CalcNLimitAverage( 
            Char.MinValue, Char.MaxValue, provider ) ) );
    }

    // Convert to DateTime by adding the calculated average as 
    // seconds to the current date and time. A valid DateTime is 
    // always returned.
    public DateTime ToDateTime( IFormatProvider provider )
    {
        double seconds = 
            Average( GetAverageInfo( provider ).TypeOfAverage );
        try
        {
            return DateTime.Now.AddSeconds( seconds );
        }
        catch( ArgumentOutOfRangeException )
        {
            return seconds < 0.0 ? DateTime.MinValue : DateTime.MaxValue;
        }
    }

    public decimal ToDecimal( IFormatProvider provider )
    {
        // The Double conversion rounds Decimal.MinValue and 
        // Decimal.MaxValue to invalid Decimal values, so the 
        // following limits must be used.
        return Convert.ToDecimal( CalcNLimitAverage( 
            -79228162514264330000000000000.0, 
            79228162514264330000000000000.0, provider ) );
    }

    public double ToDouble( IFormatProvider provider )
    {
        return Average( GetAverageInfo(provider).TypeOfAverage );
    }

    public short ToInt16( IFormatProvider provider )
    {
        return Convert.ToInt16( CalcNLimitAverage( 
            Int16.MinValue, Int16.MaxValue, provider ) );
    }

    public int ToInt32( IFormatProvider provider )
    {
        return Convert.ToInt32( CalcNLimitAverage( 
            Int32.MinValue, Int32.MaxValue, provider ) );
    }

    public long ToInt64( IFormatProvider provider )
    {
        // The Double conversion rounds Int64.MinValue and 
        // Int64.MaxValue to invalid Int64 values, so the following 
        // limits must be used.
        return Convert.ToInt64( CalcNLimitAverage( 
            -9223372036854775000, 9223372036854775000, provider ) );
    }

    public SByte ToSByte( IFormatProvider provider )
    {
        return Convert.ToSByte( CalcNLimitAverage( 
            SByte.MinValue, SByte.MaxValue, provider ) );
    }

    public float ToSingle( IFormatProvider provider )
    {
        return Convert.ToSingle( CalcNLimitAverage( 
            Single.MinValue, Single.MaxValue, provider ) );
    }

    public UInt16 ToUInt16( IFormatProvider provider )
    {
        return Convert.ToUInt16( CalcNLimitAverage( 
            UInt16.MinValue, UInt16.MaxValue, provider ) );
    }

    public UInt32 ToUInt32( IFormatProvider provider )
    {
        return Convert.ToUInt32( CalcNLimitAverage( 
            UInt32.MinValue, UInt32.MaxValue, provider ) );
    }

    public UInt64 ToUInt64( IFormatProvider provider )
    {
        // The Double conversion rounds UInt64.MaxValue to an invalid
        // UInt64 value, so the following limit must be used.
        return Convert.ToUInt64( CalcNLimitAverage( 
            0, 18446744073709550000.0, provider ) );
    }

    public object ToType( Type conversionType, 
        IFormatProvider provider )
    {
        return Convert.ChangeType( Average( 
            GetAverageInfo( provider ).TypeOfAverage ), 
            conversionType );
    }

    public string ToString( IFormatProvider provider )
    {
        AverageType avgType = GetAverageInfo( provider ).TypeOfAverage;
        return String.Format( "( {0}: {1:G10} )", avgType, 
            Average( avgType ) );
    }
}
   
class IConvertibleProviderDemo
{
    // Display a DataSet with three different format providers.
    public static void DisplayDataSet( DataSet ds )
    {
        string      fmt    = "{0,-12}{1,20}{2,20}{3,20}";
        AverageInfo median = new AverageInfo( AverageType.Median );
        AverageInfo geMean = 
            new AverageInfo( AverageType.GeometricMean );

         // Display the dataset elements.
        if( ds.Count > 0 )
        {
            Console.Write( "\nDataSet: [{0}", ds[ 0 ] );
            for( int iX = 1; iX < ds.Count; iX++ )
                Console.Write( ", {0}", ds[ iX ] );
            Console.WriteLine( "]\n" );
        }

        Console.WriteLine( fmt, "Convert.", "Default", 
            "Geometric Mean", "Median");
        Console.WriteLine( fmt, "--------", "-------", 
            "--------------", "------");
        Console.WriteLine( fmt, "ToBoolean", 
            Convert.ToBoolean( ds, null ), 
            Convert.ToBoolean( ds, geMean ), 
            Convert.ToBoolean( ds, median ) );
        Console.WriteLine( fmt, "ToByte", 
            Convert.ToByte( ds, null ), 
            Convert.ToByte( ds, geMean ), 
            Convert.ToByte( ds, median ) );
        Console.WriteLine( fmt, "ToChar", 
            Convert.ToChar( ds, null ), 
            Convert.ToChar( ds, geMean ), 
            Convert.ToChar( ds, median ) );
        Console.WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}" +
            "{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}", 
            "ToDateTime", Convert.ToDateTime( ds, null ), 
            Convert.ToDateTime( ds, geMean ), 
            Convert.ToDateTime( ds, median ) );
        Console.WriteLine( fmt, "ToDecimal", 
            Convert.ToDecimal( ds, null ), 
            Convert.ToDecimal( ds, geMean ), 
            Convert.ToDecimal( ds, median ) );
        Console.WriteLine( fmt, "ToDouble", 
            Convert.ToDouble( ds, null ), 
            Convert.ToDouble( ds, geMean ), 
            Convert.ToDouble( ds, median ) );
        Console.WriteLine( fmt, "ToInt16", 
            Convert.ToInt16( ds, null ), 
            Convert.ToInt16( ds, geMean ), 
            Convert.ToInt16( ds, median ) );
        Console.WriteLine( fmt, "ToInt32", 
            Convert.ToInt32( ds, null ), 
            Convert.ToInt32( ds, geMean ), 
            Convert.ToInt32( ds, median ) );
        Console.WriteLine( fmt, "ToInt64", 
            Convert.ToInt64( ds, null ), 
            Convert.ToInt64( ds, geMean ), 
            Convert.ToInt64( ds, median ) );
        Console.WriteLine( fmt, "ToSByte", 
            Convert.ToSByte( ds, null ), 
            Convert.ToSByte( ds, geMean ), 
            Convert.ToSByte( ds, median ) );
        Console.WriteLine( fmt, "ToSingle", 
            Convert.ToSingle( ds, null ), 
            Convert.ToSingle( ds, geMean ), 
            Convert.ToSingle( ds, median ) );
        Console.WriteLine( fmt, "ToUInt16", 
            Convert.ToUInt16( ds, null ), 
            Convert.ToUInt16( ds, geMean ), 
            Convert.ToUInt16( ds, median ) );
        Console.WriteLine( fmt, "ToUInt32", 
            Convert.ToUInt32( ds, null ), 
            Convert.ToUInt32( ds, geMean ), 
            Convert.ToUInt32( ds, median ) );
        Console.WriteLine( fmt, "ToUInt64", 
            Convert.ToUInt64( ds, null ), 
            Convert.ToUInt64( ds, geMean ), 
            Convert.ToUInt64( ds, median ) );
    }
   
    public static void Main( )
    {
        Console.WriteLine( "This example of " +
            "the Convert.To<Type>( object, IFormatProvider ) methods " +
            "\ngenerates the following output. The example " +
            "displays the values \nreturned by the methods, " +
            "using several IFormatProvider objects.\n" );
          
        DataSet ds1 = new DataSet( 
            10.5, 22.2, 45.9, 88.7, 156.05, 297.6 );
        DisplayDataSet( ds1 );
          
        DataSet ds2 = new DataSet( 
            359999.95, 425000, 499999.5, 775000, 1695000 );
        DisplayDataSet( ds2 );
    }
}

/*
This example of the Convert.To<Type>( object, IFormatProvider ) methods
generates the following output. The example displays the values
returned by the methods, using several IFormatProvider objects.

DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]

Convert.                 Default      Geometric Mean              Median
--------                 -------      --------------              ------
ToBoolean                   True                True                True
ToByte                       103                  59                  67
ToChar                         g                   ;                   C
ToDateTime   2003-05-13 15:04:12 2003-05-13 15:03:28 2003-05-13 15:03:35
ToDecimal       103.491666666667    59.4332135445164                67.3
ToDouble        103.491666666667    59.4332135445164                67.3
ToInt16                      103                  59                  67
ToInt32                      103                  59                  67
ToInt64                      103                  59                  67
ToSByte                      103                  59                  67
ToSingle                103.4917            59.43321                67.3
ToUInt16                     103                  59                  67
ToUInt32                     103                  59                  67
ToUInt64                     103                  59                  67

DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]

Convert.                 Default      Geometric Mean              Median
--------                 -------      --------------              ------
ToBoolean                   True                True                True
ToByte                       255                 255                 255
ToChar                         ?                   ?                   ?
ToDateTime   2003-05-22 07:39:08 2003-05-20 22:28:45 2003-05-19 09:55:48
ToDecimal              750999.89    631577.237188435            499999.5
ToDouble               750999.89    631577.237188435            499999.5
ToInt16                    32767               32767               32767
ToInt32                   751000              631577              500000
ToInt64                   751000              631577              500000
ToSByte                      127                 127                 127
ToSingle                750999.9            631577.3            499999.5
ToUInt16                   65535               65535               65535
ToUInt32                  751000              631577              500000
ToUInt64                  751000              631577              500000
*/
Imports System.Collections

Module IConvertibleProviderDemo

    ' Define the types of averaging available in the class 
    ' implementing IConvertible.
    Enum AverageType as Short
        None = 0
        GeometricMean = 1
        ArithmeticMean = 2
        Median = 3
    End Enum

    ' Pass an instance of this class to methods that require an 
    ' IFormatProvider. The class instance determines the type of 
    ' average to calculate.
    Public Class AverageInfo
        Implements IFormatProvider

        Protected  AvgType      As AverageType

        ' Specify the type of averaging in the constructor.
        Public Sub New( avgType As AverageType )
            Me.AvgType = avgType
        End Sub

        ' This method returns a reference to the containing object 
        ' if an object of AverageInfo type is requested. 
        Public Function GetFormat( argType As Type ) As Object _
            Implements IFormatProvider.GetFormat

            If argType Is GetType( AverageInfo ) Then
                Return Me
            Else
                Return Nothing
            End If
        End Function 

        ' Use this property to set or get the type of averaging.
        Public Property TypeOfAverage( ) As AverageType
            Get
                Return Me.AvgType
            End Get
            Set( ByVal value as AverageType )
                Me.AvgType = value
            End Set
        End Property
    End Class 

    ' This class encapsulates an array of Double values and implements 
    ' the IConvertible interface. Most of the IConvertible methods 
    ' return an average of the array elements in one of three types: 
    ' arithmetic mean, geometric mean, or median. 
    Public Class DataSet
        Implements IConvertible

        Protected data              As ArrayList
        Protected defaultProvider   As AverageInfo
           
        ' Construct the object and add an initial list of values.
        ' Create a default format provider.
        Public Sub New( ParamArray values( ) As Double )
            data = New ArrayList( values )
            defaultProvider = New AverageInfo( _
                AverageType.ArithmeticMean )  
        End Sub
           
        ' Add additional values with this method.
        Public Function Add( value As Double ) As Integer
            data.Add( value )
            Return data.Count
        End Function
           
        ' Get, set, and add values with this indexer property.
        Default Public Property Item(index As Integer) As Double
            Get
                If index >= 0 AndAlso index < data.Count Then
                    Return System.Convert.ToDouble( data( index ) )
                Else
                    Throw New InvalidOperationException( _
                        "[DataSet.get] Index out of range." )
                End If
            End Get
            Set
                If index >= 0 AndAlso index < data.Count Then
                    data( index ) = value
                 
                ElseIf index = data.Count Then
                    data.Add( value )
                Else
                    Throw New InvalidOperationException( _
                        "[DataSet.set] Index out of range." )
                End If
            End Set
        End Property
          
        ' This property returns the number of elements in the object.
        Public ReadOnly Property Count( ) As Integer
            Get
                Return data.Count
            End Get
        End Property

        ' This method calculates the average of the object's elements.
        Protected Function Average( ByVal avgType As AverageType ) As Double

            Dim SumProd As Double 
            Dim Index   As Integer

            If data.Count = 0 Then Return 0.0

            Select Case avgType
                
                Case AverageType.GeometricMean

                    SumProd = 1.0
                    For Index = 0 To data.Count - 1
                        SumProd *= data( Index )
                    Next Index
                    
                    ' This calculation will not fail with negative 
                    ' elements.
                    Return Math.Sign( SumProd ) * Math.Pow( _
                        Math.Abs( SumProd ), 1.0 / data.Count )

                Case AverageType.ArithmeticMean

                    SumProd = 0.0
                    For Index = 0 To data.Count - 1
                        SumProd += data( Index )
                    Next Index

                    Return SumProd / data.Count 

                Case AverageType.Median

                    If data.Count Mod 2 = 0 Then
                        Return ( data( data.Count \ 2 ) + _
                            data( data.Count \ 2 - 1 ) ) / 2.0
                    Else
                        Return data( data.Count \ 2 ) 
                    End If
            End Select
        End Function

        ' Get the AverageInfo object from the caller's format 
        ' provider, or use the local default.
        Protected Function GetAverageInfo( _
            provider As IFormatProvider ) As AverageInfo

            Dim avgInfo As AverageInfo = Nothing

            If Not provider Is Nothing Then
                avgInfo = provider.GetFormat( GetType( AverageInfo ) )
            End If

            Return IIf( avgInfo Is Nothing, defaultProvider, avgInfo )
            
        End Function           

        ' Calculate the average and limit the range.
        Protected Function CalcNLimitAverage( min As Double, _
            max As Double, provider as IFormatProvider ) As Double

            ' Get the format provider and calculate the average.
            Dim avgInfo As AverageInfo = GetAverageInfo( provider )
            Dim avg As Double = Average( avgInfo.TypeOfAverage )

            ' Limit the range, based on the minimum and maximum values 
            ' for the type.
            Return IIf( avg > max, max, IIf( avg < min, min, avg ) )

        End Function

        ' The following elements are required by IConvertible.

        ' None of these conversion functions throw exceptions. When
        ' the data is out of range for the type, the appropriate
        ' MinValue or MaxValue is used.
        Public Function GetTypeCode( ) As TypeCode _
            Implements IConvertible.GetTypeCode
            Return TypeCode.Object
        End Function

        Function ToBoolean( ByVal provider As IFormatProvider ) As _
            Boolean Implements IConvertible.ToBoolean

            ' ToBoolean is false if the dataset is empty.
            If data.Count <= 0 Then
                Return False

            ' For median averaging, ToBoolean is true if any 
            ' non-discarded elements are nonzero.
            ElseIf AverageType.Median = _
                GetAverageInfo( provider ).TypeOfAverage Then

                If data.Count Mod 2 = 0 Then
                    Return ( data( data.Count \ 2 ) <> 0.0 Or _
                        data( data.Count \ 2 - 1 ) <> 0.0 )
                Else
                    Return data( data.Count \ 2 ) <> 0.0
                End If

            ' For arithmetic or geometric mean averaging, ToBoolean is 
            ' true if any element of the dataset is nonzero.  
            Else
                Dim Index As Integer
                For Index = 0 To data.Count - 1
                    If data( Index ) <> 0.0 Then Return True
                Next Index
                Return False
            End If
        End Function

        Function ToByte( ByVal provider As IFormatProvider ) As Byte _
            Implements IConvertible.ToByte
            Return Convert.ToByte( CalcNLimitAverage( _
                Byte.MinValue, Byte.MaxValue, provider ) )
        End Function

        Function ToChar( ByVal provider As IFormatProvider ) As Char _
            Implements IConvertible.ToChar
            Return Convert.ToChar( Convert.ToUInt16( _
                CalcNLimitAverage( 0.0, &HFFFF, provider ) ) )
        End Function

        ' Convert to DateTime by adding the calculated average as 
        ' seconds to the current date and time. A valid DateTime is 
        ' always returned.
        Function ToDateTime( ByVal provider As IFormatProvider ) As _
            DateTime Implements IConvertible.ToDateTime
            Dim seconds As Double = Average( _
                GetAverageInfo( provider ).TypeOfAverage )
            Try
                Return DateTime.Now.AddSeconds( seconds )
            Catch ex As ArgumentOutOfRangeException 
                Return IIf( seconds < 0.0, DateTime.MinValue, _
                    DateTime.MaxValue )
            End Try
        End Function

        Function ToDecimal( ByVal provider As IFormatProvider ) As _
            Decimal Implements IConvertible.ToDecimal

            ' The Double conversion rounds Decimal.MinValue and
            ' Decimal.MaxValue to invalid Decimal values, so the 
            ' following limits must be used.
            Return Convert.ToDecimal( CalcNLimitAverage( _
                -79228162514264330000000000000.0, _
                79228162514264330000000000000.0, provider ) )
        End Function

        Function ToDouble( ByVal provider As IFormatProvider) As _
            Double Implements IConvertible.ToDouble
            Return Average( GetAverageInfo( provider ).TypeOfAverage )
        End Function

        Function ToInt16( ByVal provider As IFormatProvider ) As _
            Short Implements IConvertible.ToInt16
            Return Convert.ToInt16( CalcNLimitAverage( _
                Int16.MinValue, Int16.MaxValue, provider ) )
        End Function

        Function ToInt32( ByVal provider As IFormatProvider ) As _
            Integer Implements IConvertible.ToInt32
            Return Convert.ToInt32( CalcNLimitAverage( _
                Int32.MinValue, Int32.MaxValue, provider ) )
        End Function

        Function ToInt64( ByVal provider As IFormatProvider ) As Long _
            Implements IConvertible.ToInt64

            ' The Double conversion rounds Int64.MinValue and 
            ' Int64.MaxValue to invalid Long values, so the following 
            ' limits must be used.
            Return Convert.ToInt64( CalcNLimitAverage( _
                -9223372036854775000, 9223372036854775000, provider ) )
        End Function

        Function ToSByte( ByVal provider As IFormatProvider ) As _
            SByte Implements IConvertible.ToSByte

            ' SByte.MinValue and SByte.MaxValue are not defined in
            ' Visual Basic.
            Return Convert.ToSByte( CalcNLimitAverage( _
                -128, 127, provider ) )
        End Function

        Function ToSingle( ByVal provider As IFormatProvider ) As _
            Single Implements IConvertible.ToSingle
            Return Convert.ToSingle( CalcNLimitAverage( _
                Single.MinValue, Single.MaxValue, provider ) )
        End Function

        Function ToUInt16( ByVal provider As IFormatProvider ) As _
            UInt16 Implements IConvertible.ToUInt16

            ' UInt16.MinValue and UInt16.MaxValue are not defined in 
            ' Visual Basic.
            Return Convert.ToUInt16( CalcNLimitAverage( _
                0, &HFFFF, provider ) )
        End Function

        Function ToUInt32( ByVal provider As IFormatProvider ) As _
            UInt32 Implements IConvertible.ToUInt32

            ' UInt32.MinValue and UInt32.MaxValue are not defined in 
            ' Visual Basic.
            Return Convert.ToUInt32( CalcNLimitAverage( _
                0, 4294967295, provider ) )
        End Function

        Function ToUInt64( ByVal provider As IFormatProvider ) As _
            UInt64 Implements IConvertible.ToUInt64

            ' UInt64.MinValue and UInt64.MaxValue are not defined in 
            ' Visual Basic. The Double conversion would have rounded 
            ' UInt64.MaxValue, so the following limit must be used.
            Return Convert.ToUInt64( CalcNLimitAverage( _
                0, 18446744073709550000.0, provider ) )
        End Function

        Function ToType( ByVal conversionType As Type, _
            ByVal provider As IFormatProvider) As Object _
            Implements IConvertible.ToType
            Return Convert.ChangeType( Average( GetAverageInfo( _
                provider ).TypeOfAverage ), conversionType )
        End Function

        Overloads Function ToString( ByVal provider As IFormatProvider _
            ) As String Implements IConvertible.ToString
            Dim avgType as AverageType = _
                GetAverageInfo( provider ).TypeOfAverage
            Return String.Format( "( {0}: {1:G10} )", avgType, _
                Average( avgType ) )
        End Function
    End Class
   
    ' Display a DataSet with three different format providers.
    Sub DisplayDataSet( ds As DataSet )

        Dim fmt    As String      = "{0,-12}{1,20}{2,20}{3,20}"
        Dim median As AverageInfo = New AverageInfo( AverageType.Median )
        Dim geMean As AverageInfo = _
            New AverageInfo( AverageType.GeometricMean )
        Dim iX     As Integer

        ' Display the dataset elements.
        If ds.Count > 0 Then
            Console.Write( vbCrLf & "DataSet: [{0}", ds( 0 ) )
            For iX = 1 To ds.Count - 1
                Console.Write( ", {0}", ds( iX ) )
            Next iX
            Console.WriteLine( "]" & vbCrLf )
        End If

        Console.WriteLine( fmt, "Convert.", "Default", _
            "Geometric Mean", "Median" )
        Console.WriteLine( fmt, "--------", "-------", _
            "--------------", "------" )
        Console.WriteLine( fmt, "ToBoolean", _
            Convert.ToBoolean( ds, Nothing ), _
            Convert.ToBoolean( ds, geMean ), _
            Convert.ToBoolean( ds, median ) )
        Console.WriteLine( fmt, "ToByte", _
            Convert.ToByte( ds, Nothing ), _
            Convert.ToByte( ds, geMean ), _
            Convert.ToByte( ds, median ) )
        Console.WriteLine( fmt, "ToChar", _
            Convert.ToChar( ds, Nothing ), _
            Convert.ToChar( ds, geMean ), _
            Convert.ToChar( ds, median ) )
        Console.WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}" & _
            "{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}", _
            "ToDateTime", Convert.ToDateTime( ds, Nothing ), _
            Convert.ToDateTime( ds, geMean ), _
            Convert.ToDateTime( ds, median ) )
        Console.WriteLine( fmt, "ToDecimal", _
            Convert.ToDecimal( ds, Nothing ), _
            Convert.ToDecimal( ds, geMean ), _
            Convert.ToDecimal( ds, median ) )
        Console.WriteLine( fmt, "ToDouble", _
            Convert.ToDouble( ds, Nothing ), _
            Convert.ToDouble( ds, geMean ), _
            Convert.ToDouble( ds, median ) )
        Console.WriteLine( fmt, "ToInt16", _
            Convert.ToInt16( ds, Nothing ), _
            Convert.ToInt16( ds, geMean ), _
            Convert.ToInt16( ds, median ) )
        Console.WriteLine( fmt, "ToInt32", _
            Convert.ToInt32( ds, Nothing ), _
            Convert.ToInt32( ds, geMean ), _
            Convert.ToInt32( ds, median ) )
        Console.WriteLine( fmt, "ToInt64", _
            Convert.ToInt64( ds, Nothing ), _
            Convert.ToInt64( ds, geMean ), _
            Convert.ToInt64( ds, median ) )
        Console.WriteLine( fmt, "ToSByte", _
            Convert.ToSByte( ds, Nothing ), _
            Convert.ToSByte( ds, geMean ), _
            Convert.ToSByte( ds, median ) )
        Console.WriteLine( fmt, "ToSingle", _
            Convert.ToSingle( ds, Nothing ), _
            Convert.ToSingle( ds, geMean ), _
            Convert.ToSingle( ds, median ) )
        Console.WriteLine( fmt, "ToUInt16", _
            Convert.ToUInt16( ds, Nothing ), _
            Convert.ToUInt16( ds, geMean ), _
            Convert.ToUInt16( ds, median ) )
        Console.WriteLine( fmt, "ToUInt32", _
            Convert.ToUInt32( ds, Nothing ), _
            Convert.ToUInt32( ds, geMean ), _
            Convert.ToUInt32( ds, median ) )
        Console.WriteLine( fmt, "ToUInt64", _
            Convert.ToUInt64( ds, Nothing ), _
            Convert.ToUInt64( ds, geMean ), _
            Convert.ToUInt64( ds, median ) )
    End Sub
   
    Sub Main( )
        Console.WriteLine( _
            "This example of the Convert.To<Type>( Object, " & _
            "IFormatProvider ) methods " & vbCrLf & "generates " & _
            "the following output. The example displays the " & _
            "values " & vbCrLf & "returned by the methods, " & _
            "using several IFormatProvider objects." & vbCrLf )
          
        Dim ds1 As New DataSet( 10.5, 22.2, 45.9, 88.7, 156.05, 297.6 )
        DisplayDataSet( ds1 )
          
        Dim ds2 As New DataSet( _
            359999.95, 425000, 499999.5, 775000, 1695000 )
        DisplayDataSet( ds2 )
    End Sub 
End Module 

' This example of the Convert.To<Type>( Object, IFormatProvider ) methods
' generates the following output. The example displays the values
' returned by the methods, using several IFormatProvider objects.
' 
' DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
' 
' Convert.                 Default      Geometric Mean              Median
' --------                 -------      --------------              ------
' ToBoolean                   True                True                True
' ToByte                       103                  59                  67
' ToChar                         g                   ;                   C
' ToDateTime   2003-05-13 14:52:53 2003-05-13 14:52:09 2003-05-13 14:52:17
' ToDecimal       103.491666666667    59.4332135445164                67.3
' ToDouble        103.491666666667    59.4332135445164                67.3
' ToInt16                      103                  59                  67
' ToInt32                      103                  59                  67
' ToInt64                      103                  59                  67
' ToSByte                      103                  59                  67
' ToSingle                103.4917            59.43321                67.3
' ToUInt16                     103                  59                  67
' ToUInt32                     103                  59                  67
' ToUInt64                     103                  59                  67
' 
' DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
' 
' Convert.                 Default      Geometric Mean              Median
' --------                 -------      --------------              ------
' ToBoolean                   True                True                True
' ToByte                       255                 255                 255
' ToChar                         ?                   ?                   ?
' ToDateTime   2003-05-22 07:27:49 2003-05-20 22:17:27 2003-05-19 09:44:29
' ToDecimal              750999.89    631577.237188435            499999.5
' ToDouble               750999.89    631577.237188435            499999.5
' ToInt16                    32767               32767               32767
' ToInt32                   751000              631577              500000
' ToInt64                   751000              631577              500000
' ToSByte                      127                 127                 127
' ToSingle                750999.9            631577.3            499999.5
' ToUInt16                   65535               65535               65535
' ToUInt32                  751000              631577              500000
' ToUInt64                  751000              631577              500000

Remarques

La valeur de retour est le résultat de l’appel de la méthode IConvertible.ToChar du type sous-jacent de value.The return value is the result of invoking the IConvertible.ToChar method of the underlying type of value.

provider permet à l’utilisateur de spécifier des informations de conversion spécifiques à la culture concernant le contenu de value.provider enables the user to specify culture-specific conversion information about the contents of value. Les types de base ignorent provider; Toutefois, le paramètre peut être utilisé si value est un type défini par l’utilisateur qui implémente l’interface IConvertible.The base types ignore provider; however, the parameter may be used if value is a user-defined type that implements the IConvertible interface.

ToChar(UInt64)

Important

Cette API n’est pas conforme CLS.

Convertit la valeur de l'entier non signé 64 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 64-bit unsigned integer to its equivalent Unicode character.

public:
 static char ToChar(System::UInt64 value);
[System.CLSCompliant(false)]
public static char ToChar (ulong value);
static member ToChar : uint64 -> char
Public Shared Function ToChar (value As ULong) As Char

Paramètres

value
UInt64

Entier non signé 64 bits à convertir.The 64-bit unsigned integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Attributs

Exceptions

value est supérieur à MaxValue.value is greater than MaxValue.

Exemples

L’exemple suivant convertit chaque élément d’un tableau d’entiers longs non signés en une valeur Char.The following example converts each element in an array of unsigned long integers to a Char value.

ulong[] numbers = { UInt64.MinValue, 40, 160, 255, 1028,
                    2011, 30001, 207154, Int64.MaxValue };
char result;
foreach (ulong number in numbers)
{
   try {
      result = Convert.ToChar(number);
      Console.WriteLine("{0} converts to '{1}'.", number, result);
   }
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Char data type.",
                        number);
   }
}   
// The example displays the following output:
//       0 converts to ' '.
//       40 converts to '('.
//       160 converts to ' '.
//       255 converts to 'ÿ'.
//       1028 converts to '?'.
//       2011 converts to '?'.
//       30001 converts to '?'.
//       207154 is outside the range of the Char data type.
//       9223372036854775807 is outside the range of the Char data type.
Dim numbers() As ULong = { UInt64.MinValue, 40, 160, 255, 1028, _
                              2011, 30001, 207154, Int64.MaxValue }
Dim result As Char
For Each number As ULong In numbers
   Try
      result = Convert.ToChar(number)
      Console.WriteLine("{0} converts to '{1}'.", number, result)
   Catch e As OverflowException
      Console.WriteLine("{0} is outside the range of the Char data type.", _
                        number)
   End Try
Next   
' The example displays the following output:
'       0 converts to ' '.
'       40 converts to '('.
'       160 converts to ' '.
'       255 converts to 'ÿ'.
'       1028 converts to '?'.
'       2011 converts to '?'.
'       30001 converts to '?'.
'       207154 is outside the range of the Char data type.
'       9223372036854775807 is outside the range of the Char data type.

ToChar(UInt32)

Important

Cette API n’est pas conforme CLS.

Convertit la valeur de l'entier non signé 32 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 32-bit unsigned integer to its equivalent Unicode character.

public:
 static char ToChar(System::UInt32 value);
[System.CLSCompliant(false)]
public static char ToChar (uint value);
static member ToChar : uint32 -> char
Public Shared Function ToChar (value As UInteger) As Char

Paramètres

value
UInt32

Entier non signé 32 bits à convertir.The 32-bit unsigned integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Attributs

Exceptions

value est supérieur à MaxValue.value is greater than MaxValue.

Exemples

L’exemple suivant convertit chaque élément d’un tableau d’entiers non signés en une valeur Char.The following example converts each element in an array of unsigned integers to a Char value.

uint[] numbers = { UInt32.MinValue, 40, 160, 255, 1028,
                   2011, 30001, 207154, Int32.MaxValue };
char result;
foreach (uint number in numbers)
{
   try {
      result = Convert.ToChar(number);
      Console.WriteLine("{0} converts to '{1}'.", number, result);
   }   
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Char data type.",
                        number);
   }
}   
// The example displays the following output:
//       0 converts to ' '.
//       40 converts to '('.
//       160 converts to ' '.
//       255 converts to 'ÿ'.
//       1028 converts to '?'.
//       2011 converts to '?'.
//       30001 converts to '?'.
//       207154 is outside the range of the Char data type.
//       2147483647 is outside the range of the Char data type.
Dim numbers() As UInteger = { UInt32.MinValue, 40, 160, 255, 1028, _
                              2011, 30001, 207154, Int32.MaxValue }
Dim result As Char
For Each number As UInteger In numbers
   Try
      result = Convert.ToChar(number)
      Console.WriteLine("{0} converts to '{1}'.", number, result)
   Catch e As OverflowException
      Console.WriteLine("{0} is outside the range of the Char data type.", _
                        number)
   End Try
Next   
' The example displays the following output:
'       0 converts to ' '.
'       40 converts to '('.
'       160 converts to ' '.
'       255 converts to 'ÿ'.
'       1028 converts to '?'.
'       2011 converts to '?'.
'       30001 converts to '?'.
'       207154 is outside the range of the Char data type.
'       2147483647 is outside the range of the Char data type.

ToChar(UInt16)

Important

Cette API n’est pas conforme CLS.

Convertit la valeur de l'entier non signé 16 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 16-bit unsigned integer to its equivalent Unicode character.

public:
 static char ToChar(System::UInt16 value);
[System.CLSCompliant(false)]
public static char ToChar (ushort value);
static member ToChar : uint16 -> char
Public Shared Function ToChar (value As UShort) As Char

Paramètres

value
UInt16

Entier non signé 16 bits à convertir.The 16-bit unsigned integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Attributs

Exemples

L’exemple suivant convertit chaque élément d’un tableau d’entiers 16 bits non signés en une valeur Char.The following example converts each element in an array of unsigned 16-bit integers to a Char value.

ushort[] numbers = { UInt16.MinValue, 40, 160, 255, 1028, 
                     2011, UInt16.MaxValue };
char result;
foreach (ushort number in numbers)
{
   result = Convert.ToChar(number);
   Console.WriteLine("{0} converts to '{1}'.", number, result);
}   
// The example displays the following output:
//       0 converts to ' '.
//       40 converts to '('.
//       160 converts to ' '.
//       255 converts to 'ÿ'.
//       1028 converts to '?'.
//       2011 converts to '?'.
//       65535 converts to '?'.
Dim numbers() As UShort = { UInt16.MinValue, 40, 160, 255, 1028, _
                            2011, UInt16.MaxValue }
Dim result As Char
For Each number As UShort In numbers
   result = Convert.ToChar(number)
   Console.WriteLine("{0} converts to '{1}'.", number, result)
Next   
' The example displays the following output:
'       0 converts to ' '.
'       40 converts to '('.
'       160 converts to ' '.
'       255 converts to 'ÿ'.
'       1028 converts to '?'.
'       2011 converts to '?'.
'       65535 converts to '?'.

ToChar(String)

Convertit le premier caractère d'une chaîne spécifiée en caractère Unicode.Converts the first character of a specified string to a Unicode character.

public:
 static char ToChar(System::String ^ value);
public static char ToChar (string value);
static member ToChar : string -> char
Public Shared Function ToChar (value As String) As Char

Paramètres

value
String

Chaîne de longueur 1.A string of length 1.

Retours

Caractère Unicode qui est équivalent au premier et unique caractère de value.A Unicode character that is equivalent to the first and only character in value.

Exceptions

value a la valeur null.value is null.

La longueur de value n’est pas égale à 1.The length of value is not 1.

Exemples

L’exemple suivant convertit chaque élément d’un tableau de chaînes en une valeur Char.The following example converts each element in a string array to a Char value.

string nullString = null;
string[] strings = { "A", "This",  '\u0007'.ToString(), nullString };
char result;
foreach (string strng in strings)
{
   try {
      result = Convert.ToChar(strng);
      Console.WriteLine("'{0}' converts to '{1}'.", strng, result);
   }   
   catch (FormatException)
   {
      Console.WriteLine("'{0}' is not in the correct format for conversion to a Char.",
                        strng);
   }
   catch (ArgumentNullException) {
      Console.WriteLine("A null string cannot be converted to a Char.");
   }   
}
// The example displays the following output:
//       'A' converts to 'A'.
//       'This' is not in the correct format for conversion to a Char.
//       '       ' converts to ' '.
//       A null string cannot be converted to a Char.
Dim nullString As String = Nothing
Dim strings() As String = { "A", "This", vbTab, nullString }
Dim result As Char
For Each strng As String In strings
   Try
      result = Convert.ToChar(strng)
      Console.WriteLine("'{0}' converts to '{1}'.", strng, result)
   Catch e As FormatException
      Console.WriteLine("'{0}' is not in the correct format for conversion to a Char.", _
                        strng)
   Catch e As ArgumentNullException
      Console.WriteLine("A null string cannot be converted to a Char.")
   End Try
Next
' The example displays the following output:
'       'A' converts to 'A'.
'       'This' is not in the correct format for conversion to a Char.
'       '       ' converts to ' '.
'       A null string cannot be converted to a Char.

Remarques

value doit être une chaîne qui contient un seul caractère.value must be a string that contains a single character.

Si vous préférez ne pas gérer une exception en cas d’échec de la conversion, vous pouvez appeler la méthode Char.TryParse à la place.If you prefer not to handle an exception if the conversion fails, you can call the Char.TryParse method instead. Elle retourne une valeur Boolean qui indique si la conversion a réussi ou a échoué.It returns a Boolean value that indicates whether the conversion succeeded or failed.

ToChar(Single)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

public:
 static char ToChar(float value);
public static char ToChar (float value);
static member ToChar : single -> char
Public Shared Function ToChar (value As Single) As Char

Paramètres

value
Single

Nombre à virgule flottante simple précision à convertir.The single-precision floating-point number to convert.

Retours

Cette conversion n'est pas prise en charge.This conversion is not supported. Aucune valeur n'est retournée.No value is returned.

Exceptions

Cette conversion n'est pas prise en charge.This conversion is not supported.

ToChar(SByte)

Important

Cette API n’est pas conforme CLS.

Convertit la valeur de l'entier signé 8 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 8-bit signed integer to its equivalent Unicode character.

public:
 static char ToChar(System::SByte value);
[System.CLSCompliant(false)]
public static char ToChar (sbyte value);
static member ToChar : sbyte -> char
Public Shared Function ToChar (value As SByte) As Char

Paramètres

value
SByte

Entier signé 8 bits à convertir.The 8-bit signed integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Attributs

Exceptions

value est inférieur à MinValue.value is less than MinValue.

Exemples

L’exemple suivant convertit un tableau d’octets signés en valeurs Char.The following example converts an array of signed bytes to Char values.

sbyte[] numbers = { SByte.MinValue, -1, 40, 80, 120, SByte.MaxValue };
char result;
foreach (sbyte number in numbers)
{
   try {
      result = Convert.ToChar(number);
      Console.WriteLine("{0} converts to '{1}'.", number, result);
   }   
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Char data type.",
                        number);
   }
}
// The example displays the following output:
//       -128 is outside the range of the Char data type.
//       -1 is outside the range of the Char data type.
//       40 converts to '('.
//       80 converts to 'P'.
//       120 converts to 'x'.
//       127 converts to '⌂'.
Dim numbers() As SByte = { SByte.MinValue, -1, 40, 80, 120, SByte.MaxValue }
Dim result As Char
For Each number As SByte In numbers
   Try
      result = Convert.ToChar(number)
      Console.WriteLine("{0} converts to '{1}'.", number, result)
   Catch e As OverflowException
      Console.WriteLine("{0} is outside the range of the Char data type.", _
                        number)
   End Try
Next
' The example displays the following output:
'       -128 is outside the range of the Char data type.
'       -1 is outside the range of the Char data type.
'       40 converts to '('.
'       80 converts to 'P'.
'       120 converts to 'x'.
'       127 converts to '⌂'.

ToChar(Int64)

Convertit la valeur de l'entier signé 64 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 64-bit signed integer to its equivalent Unicode character.

public:
 static char ToChar(long value);
public static char ToChar (long value);
static member ToChar : int64 -> char
Public Shared Function ToChar (value As Long) As Char

Paramètres

value
Int64

Entier signé 64 bits à convertir.The 64-bit signed integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Exceptions

value est inférieur à MinValue ou supérieur à MaxValue.value is less than MinValue or greater than MaxValue.

Exemples

L’exemple suivant tente de convertir un entier long en Charet lève une OverflowException en cas d’échec.The following example attempts to convert a long integer to a Char, and throws a OverflowException on failure.

public:
   void ConvertLongChar( Int64 longVal )
   {
      Char charVal = 'a';

      try
      {
         charVal = System::Convert::ToChar( longVal );
         System::Console::WriteLine( " {0} as a char is {1}",
         longVal, charVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine( "Overflow in long-to-char conversion." );
      }

      
      // A conversion from Char to long cannot overflow.
      longVal = System::Convert::ToInt64( charVal );
      System::Console::WriteLine( " {0} as an Int64 is {1}",
         charVal, longVal );
   }


public void ConvertLongChar(long longVal) {

    char	charVal = 'a';

    try {
        charVal = System.Convert.ToChar(longVal);
        System.Console.WriteLine("{0} as a char is {1}",
            longVal, charVal);
    } 
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "Overflow in long-to-char conversion.");
    }
    
    // A conversion from Char to long cannot overflow.
    longVal = System.Convert.ToInt64(charVal);
    System.Console.WriteLine("{0} as an Int64 is {1}",
        charVal, longVal);
}
Public Sub ConvertLongChar(ByVal longVal As Long)

    Dim charVal As Char = "a"c

    Try
        charVal = System.Convert.ToChar(longVal)
        System.Console.WriteLine("{0} as a char is {1}", _
                                  longVal, charVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in Long-to-Char conversion.")
    End Try

    ' A conversion from Char to Long cannot overflow.
    longVal = System.Convert.ToInt64(charVal)
    System.Console.WriteLine("{0} as a Long is {1}", _
                              charVal, longVal)
End Sub

ToChar(Int16)

Convertit la valeur de l'entier signé 16 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 16-bit signed integer to its equivalent Unicode character.

public:
 static char ToChar(short value);
public static char ToChar (short value);
static member ToChar : int16 -> char
Public Shared Function ToChar (value As Short) As Char

Paramètres

value
Int16

Entier signé 16 bits à convertir.The 16-bit signed integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Exceptions

value est inférieur à MinValue.value is less than MinValue.

Exemples

L’exemple suivant convertit un tableau d’entiers 16 bits signés en valeurs Char.The following example converts an array of signed 16-bit integers to Char values.

short[] numbers = { Int16.MinValue, 0, 40, 160, 255, 1028, 
                    2011, Int16.MaxValue };
char result;
foreach (short number in numbers)
{
   try {
      result = Convert.ToChar(number);
      Console.WriteLine("{0} converts to '{1}'.", number, result);
   }   
   catch (OverflowException) {
      Console.WriteLine("{0} is outside the range of the Char data type.", 
                        number);
   }
}   
// The example displays the following output:
//       -32768 is outside the range of the Char data type.
//       0 converts to ' '.
//       40 converts to '('.
//       160 converts to ' '.
//       255 converts to 'ÿ'.
//       1028 converts to '?'.
//       2011 converts to '?'.
//       32767 converts to '?'.      
Dim numbers() As Short = { Int16.MinValue, 0, 40, 160, 255, 1028, _
                           2011, Int16.MaxValue }
Dim result As Char
For Each number As Short In numbers
   Try
      result = Convert.ToChar(number)
      Console.WriteLine("{0} converts to '{1}'.", number, result)
   Catch e As OverflowException
      Console.WriteLine("{0} is outside the range of the Char data type.", _
                        number)
   End Try
Next   
' The example displays the following output:
'       -32768 is outside the range of the Char data type.
'       0 converts to ' '.
'       40 converts to '('.
'       160 converts to ' '.
'       255 converts to 'ÿ'.
'       1028 converts to '?'.
'       2011 converts to '?'.
'       32767 converts to '?'.      

ToChar(Double)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

public:
 static char ToChar(double value);
public static char ToChar (double value);
static member ToChar : double -> char
Public Shared Function ToChar (value As Double) As Char

Paramètres

value
Double

Nombre à virgule flottante double précision à convertir.The double-precision floating-point number to convert.

Retours

Cette conversion n'est pas prise en charge.This conversion is not supported. Aucune valeur n'est retournée.No value is returned.

Exceptions

Cette conversion n'est pas prise en charge.This conversion is not supported.

ToChar(Decimal)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

public:
 static char ToChar(System::Decimal value);
public static char ToChar (decimal value);
static member ToChar : decimal -> char
Public Shared Function ToChar (value As Decimal) As Char

Paramètres

value
Decimal

Nombre décimal à convertir.The decimal number to convert.

Retours

Cette conversion n'est pas prise en charge.This conversion is not supported. Aucune valeur n'est retournée.No value is returned.

Exceptions

Cette conversion n'est pas prise en charge.This conversion is not supported.

Exemples

L’exemple suivant tente de convertir un Decimal en Charet lève InvalidCastException en cas d’échec.The following example attempts to convert a Decimal to Char, and throws InvalidCastException on failure.

public:
   void ConvertCharDecimal( Char charVal )
   {
      Decimal decimalVal = 0;
      
      // Char to decimal conversion is not supported and will always
      // throw an InvalidCastException.
      try
      {
         decimalVal = System::Convert::ToDecimal( charVal );
      }
      catch ( System::InvalidCastException^ ) 
      {
         System::Console::WriteLine(
            "Char-to-Decimal conversion is not supported by the .NET Framework." );
      }
      
      //Decimal to char conversion is also not supported.
      try
      {
         charVal = System::Convert::ToChar( decimalVal );
      }
      catch ( System::InvalidCastException^ ) 
      {
         System::Console::WriteLine(
            "Decimal-to-Char conversion is not supported by the .NET Framework." );
      }
   }
public void ConvertCharDecimal(char charVal) {
    Decimal decimalVal = 0;
    
    // Char to decimal conversion is not supported and will always
    // throw an InvalidCastException.
    try {
        decimalVal = System.Convert.ToDecimal(charVal);
    } 
    catch (System.InvalidCastException) {
        System.Console.WriteLine(
            "Char-to-Decimal conversion is not supported " +
            "by the .NET Framework.");
    }

    //Decimal to char conversion is also not supported.
    try {
        charVal = System.Convert.ToChar(decimalVal);
    } 
    catch (System.InvalidCastException) {
        System.Console.WriteLine(
            "Decimal-to-Char conversion is not supported " +
            "by the .NET Framework.");
    }
}
Public Sub ConvertCharDecimal(ByVal charVal As Char)
    Dim decimalVal As [Decimal] = 0

    ' Char to decimal conversion is not supported and will always
    ' throw an InvalidCastException.
    Try
        decimalVal = System.Convert.ToDecimal(charVal)
    Catch exception As System.InvalidCastException
        System.Console.WriteLine( _
             "Char-to-Decimal conversion is not supported " + _
             "by the .NET Framework.")
    End Try

    'Decimal to char conversion is also not supported.
    Try
        charVal = System.Convert.ToChar(decimalVal)
    Catch exception As System.InvalidCastException
        System.Console.WriteLine( _
            "Decimal-to-Char conversion is not supported " + _
            "by the .NET Framework.")
    End Try
End Sub

ToChar(DateTime)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

public:
 static char ToChar(DateTime value);
public static char ToChar (DateTime value);
static member ToChar : DateTime -> char
Public Shared Function ToChar (value As DateTime) As Char

Paramètres

value
DateTime

Valeur de date et heure à convertir.The date and time value to convert.

Retours

Cette conversion n'est pas prise en charge.This conversion is not supported. Aucune valeur n'est retournée.No value is returned.

Exceptions

Cette conversion n'est pas prise en charge.This conversion is not supported.

ToChar(Char)

Retourne la valeur du caractère Unicode spécifiée. Aucune conversion n'est effectuée.Returns the specified Unicode character value; no actual conversion is performed.

public:
 static char ToChar(char value);
public static char ToChar (char value);
static member ToChar : char -> char
Public Shared Function ToChar (value As Char) As Char

Paramètres

value
Char

Caractère Unicode à retourner.The Unicode character to return.

Retours

value est retourné sans modification.value is returned unchanged.

ToChar(Byte)

Convertit la valeur de l'entier non signé 8 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 8-bit unsigned integer to its equivalent Unicode character.

public:
 static char ToChar(System::Byte value);
public static char ToChar (byte value);
static member ToChar : byte -> char
Public Shared Function ToChar (value As Byte) As Char

Paramètres

value
Byte

Entier non signé 8 bits à convertir.The 8-bit unsigned integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Exemples

L’exemple suivant convertit un tableau d’octets non signés en valeurs Char.The following example converts an array of unsigned bytes to Char values.

byte[] bytes = {Byte.MinValue, 40, 80, 120, 180, Byte.MaxValue};
char result;
foreach (byte number in bytes)
{
   result = Convert.ToChar(number);
   Console.WriteLine("{0} converts to '{1}'.", number, result);
}
// The example displays the following output:
//       0 converts to ' '.
//       40 converts to '('.
//       80 converts to 'P'.
//       120 converts to 'x'.
//       180 converts to '''.
//       255 converts to 'ÿ'.      
Dim bytes() As Byte = {Byte.MinValue, 40, 80, 120, 180, Byte.MaxValue}
Dim result As Char
For Each number As Byte In bytes
   result = Convert.ToChar(number)
   Console.WriteLine("{0} converts to '{1}'.", number, result)
Next
' The example displays the following output:
'       0 converts to ' '.
'       40 converts to '('.
'       80 converts to 'P'.
'       120 converts to 'x'.
'       180 converts to '''.
'       255 converts to 'ÿ'.      

ToChar(Boolean)

L'appel de cette méthode lève toujours InvalidCastException.Calling this method always throws InvalidCastException.

public:
 static char ToChar(bool value);
public static char ToChar (bool value);
static member ToChar : bool -> char
Public Shared Function ToChar (value As Boolean) As Char

Paramètres

value
Boolean

Valeur booléenne à convertir.The Boolean value to convert.

Retours

Cette conversion n'est pas prise en charge.This conversion is not supported. Aucune valeur n'est retournée.No value is returned.

Exceptions

Cette conversion n'est pas prise en charge.This conversion is not supported.

ToChar(Int32)

Convertit la valeur de l'entier signé 32 bits spécifié en son caractère Unicode équivalent.Converts the value of the specified 32-bit signed integer to its equivalent Unicode character.

public:
 static char ToChar(int value);
public static char ToChar (int value);
static member ToChar : int -> char
Public Shared Function ToChar (value As Integer) As Char

Paramètres

value
Int32

Entier signé 32 bits à convertir.The 32-bit signed integer to convert.

Retours

Caractère Unicode équivalent à value.A Unicode character that is equivalent to value.

Exceptions

value est inférieur à MinValue ou supérieur à MaxValue.value is less than MinValue or greater than MaxValue.

Exemples

L’exemple suivant convertit un tableau d’entiers signés en valeurs Char.The following example converts an array of signed integers to Char values.

   int[] numbers = { -1, 0, 40, 160, 255, 1028, 
                     2011, 30001, 207154, Int32.MaxValue };
   char result;
   foreach (int number in numbers)
   {
      try {
         result = Convert.ToChar(number);
         Console.WriteLine("{0} converts to '{1}'.", number, result);
      }   
      catch (OverflowException) {
         Console.WriteLine("{0} is outside the range of the Char data type.",
                           number);
      }
   }   
}
//       -1 is outside the range of the Char data type.
//       0 converts to ' '.
//       40 converts to '('.
//       160 converts to ' '.
//       255 converts to 'ÿ'.
//       1028 converts to '?'.
//       2011 converts to '?'.
//       30001 converts to '?'.
//       207154 is outside the range of the Char data type.
//       2147483647 is outside the range of the Char data type.   
   Dim numbers() As Integer = { -1, 0, 40, 160, 255, 1028, _
                              2011, 30001, 207154, Int32.MaxValue }
   Dim result As Char
   For Each number As Integer In numbers
      Try
         result = Convert.ToChar(number)
         Console.WriteLine("{0} converts to '{1}'.", number, result)
      Catch e As OverflowException
         Console.WriteLine("{0} is outside the range of the Char data type.", _
                           number)
      End Try
   Next   
End Sub
'       -1 is outside the range of the Char data type.
'       0 converts to ' '.
'       40 converts to '('.
'       160 converts to ' '.
'       255 converts to 'ÿ'.
'       1028 converts to '?'.
'       2011 converts to '?'.
'       30001 converts to '?'.
'       207154 is outside the range of the Char data type.
'       2147483647 is outside the range of the Char data type.   

S’applique à