Convert.ToDouble Metoda

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::Object ^ value, IFormatProvider ^ provider);

public static double ToDouble (object value, IFormatProvider provider);

public static double ToDouble (object? value, IFormatProvider? provider);

static member ToDouble : obj * IFormatProvider -> double

Public Shared Function ToDouble (value As Object, provider As IFormatProvider) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá value, nebo nula, pokud value je null.

Výjimky

Příklady

Následující příklad definuje třídu, která implementuje IConvertible , a třídu, která implementuje IFormatProvider. Objekty třídy, která implementuje IConvertible , obsahují pole Double hodnot. Objekt každé třídy je předán ToDouble metodě. Tato metoda vrátí průměr pole Double hodnot pomocí objektu, který implementuje IFormatProvider k určení způsobu výpočtu průměru.

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
*/

open System
open System.Collections

// Define the types of averaging available in the class
// implementing IConvertible.
type AverageType =
    | None = 0s
    | GeometricMean = 1s
    | ArithmeticMean = 2s
    | Median = 3s

// Pass an instance of this class to methods that require an
// IFormatProvider. The class instance determines the type of
// average to calculate.
[<AllowNullLiteral>]
type AverageInfo(avgType: AverageType) =
    // Use this property to set or get the type of averaging.
    member val TypeOfAverage = avgType with get, set 
    
    interface IFormatProvider with
        // This method returns a reference to the containing object
        // if an object of AverageInfo type is requested.
        member this.GetFormat(argType: Type) =
            if argType = typeof<AverageInfo> then
                this
            else
                null

// This class encapsulates an array of double values and implements
// the IConvertible interface. Most of the IConvertible methods
// an average of the array elements in one of three types:
// arithmetic mean, geometric mean, or median.
type DataSet([<ParamArray>] values: double[]) =
    let data = ResizeArray values
    let defaultProvider =
        AverageInfo AverageType.ArithmeticMean

    // Add additional values with this method.
    member _.Add(value: double) =
        data.Add value
        data.Count

    // Get, set, and add values with this indexer property.
    member _.Item
        with get (index) =
            if index >= 0 && index < data.Count then
                data[index]
            else
                raise (InvalidOperationException "[DataSet.get] Index out of range.")
        and set index value =
            if index >= 0 && index < data.Count then
                data[index] <- value
            elif index = data.Count then
                data.Add value
            else
                raise (InvalidOperationException "[DataSet.set] Index out of range.")

    // This property returns the number of elements in the object.
    member _.Count =
        data.Count

    // This method calculates the average of the object's elements.
    member _.Average(avgType: AverageType) =
        if data.Count = 0 then
            0.0
        else
            match avgType with
            | AverageType.GeometricMean ->
                let sumProd =
                    Seq.reduce ( * ) data
                
                // This calculation will not fail with negative
                // elements.
                (sign sumProd |> float) * Math.Pow(abs sumProd, 1.0 / (float data.Count))

            | AverageType.ArithmeticMean ->
                Seq.average data

            | AverageType.Median ->
                if data.Count % 2 = 0 then
                    (data[data.Count / 2] + data[data.Count / 2 - 1]) / 2.0
                else
                    data[ data.Count / 2]
            | _ ->
                0.0

    // Get the AverageInfo object from the caller's format provider,
    // or use the local default.
    member _.GetAverageInfo(provider: IFormatProvider) =
        let avgInfo =
            if provider <> null then
                provider.GetFormat typeof<AverageInfo> :?> AverageInfo
            else 
                null

        if avgInfo = null then
            defaultProvider
        else
            avgInfo

    // Calculate the average and limit the range.
    member this.CalcNLimitAverage(min: double, max: double, provider: IFormatProvider) =
        // Get the format provider and calculate the average.
        let avgInfo = this.GetAverageInfo provider
        let avg = this.Average avgInfo.TypeOfAverage

        // Limit the range, based on the minimum and maximum values
        // for the type.
        if avg > max then max elif avg < min then min else avg

    // The following elements are required by IConvertible.
    interface IConvertible with
        // None of these conversion functions throw exceptions. When
        // the data is out of range for the type, the appropriate
        // MinValue or MaxValue is used.
        member _.GetTypeCode() =
            TypeCode.Object

        member this.ToBoolean(provider: IFormatProvider) =
            // ToBoolean is false if the dataset is empty.
            if data.Count <= 0 then
                false

            // For median averaging, ToBoolean is true if any
            // non-discarded elements are nonzero.
            elif AverageType.Median = this.GetAverageInfo(provider).TypeOfAverage then
                if data.Count % 2 = 0 then
                    (data[data.Count / 2] <> 0.0 || data[data.Count / 2 - 1] <> 0.0)
                else
                    data[data.Count / 2] <> 0.0

            // For arithmetic or geometric mean averaging, ToBoolean is
            // true if any element of the dataset is nonzero.
            else
                Seq.exists (fun x -> x <> 0.0) data

        member this.ToByte(provider: IFormatProvider) =
            Convert.ToByte(this.CalcNLimitAverage(float Byte.MinValue, float Byte.MaxValue, provider) )

        member this.ToChar(provider: IFormatProvider) =
            Convert.ToChar(Convert.ToUInt16(this.CalcNLimitAverage(float Char.MinValue, float 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.
        member this.ToDateTime(provider: IFormatProvider) =
            let seconds = this.Average(this.GetAverageInfo(provider).TypeOfAverage)
            try
                DateTime.Now.AddSeconds seconds
            with :? ArgumentOutOfRangeException ->
                if seconds < 0.0 then DateTime.MinValue else DateTime.MaxValue

        member this.ToDecimal(provider: IFormatProvider) =
            // The Double conversion rounds Decimal.MinValue and
            // Decimal.MaxValue to invalid Decimal values, so the
            // following limits must be used.
            Convert.ToDecimal(this.CalcNLimitAverage(-79228162514264330000000000000.0, 79228162514264330000000000000.0, provider) )

        member this.ToDouble(provider: IFormatProvider) =
            this.Average(this.GetAverageInfo(provider).TypeOfAverage)

        member this.ToInt16(provider: IFormatProvider) =
            Convert.ToInt16(this.CalcNLimitAverage(float Int16.MinValue, float Int16.MaxValue, provider) )

        member this.ToInt32(provider: IFormatProvider) =
            Convert.ToInt32(this.CalcNLimitAverage(Int32.MinValue, Int32.MaxValue, provider) )

        member this.ToInt64(provider: IFormatProvider) =
            // The Double conversion rounds Int64.MinValue and
            // Int64.MaxValue to invalid Int64 values, so the following
            // limits must be used.
            Convert.ToInt64(this.CalcNLimitAverage(-9223372036854775000., 9223372036854775000., provider) )

        member this.ToSByte(provider: IFormatProvider) =
            Convert.ToSByte(this.CalcNLimitAverage(float SByte.MinValue, float SByte.MaxValue, provider) )

        member this.ToSingle(provider: IFormatProvider) =
            Convert.ToSingle(this.CalcNLimitAverage(float Single.MinValue, float Single.MaxValue, provider) )

        member this.ToUInt16(provider: IFormatProvider) =
            Convert.ToUInt16(this.CalcNLimitAverage(float UInt16.MinValue, float UInt16.MaxValue, provider) )

        member this.ToUInt32(provider: IFormatProvider) =
            Convert.ToUInt32(this.CalcNLimitAverage(float UInt32.MinValue, float UInt32.MaxValue, provider) )

        member this.ToUInt64(provider: IFormatProvider) =
            // The Double conversion rounds UInt64.MaxValue to an invalid
            // UInt64 value, so the following limit must be used.
            Convert.ToUInt64(this.CalcNLimitAverage(0, 18446744073709550000.0, provider) )

        member this.ToType(conversionType: Type, provider: IFormatProvider) =
            Convert.ChangeType(this.Average(this.GetAverageInfo(provider).TypeOfAverage), conversionType)

        member this.ToString(provider: IFormatProvider) =
            let avgType = this.GetAverageInfo(provider).TypeOfAverage
            $"( {avgType}: {this.Average avgType:G10} )"                

// Display a DataSet with three different format providers.
let displayDataSet (ds: DataSet) =
    let fmt obj1 obj2 obj3 obj4 = printfn $"{obj1,-12}{obj2,20}{obj3,20}{obj4,20}"
    let median = AverageInfo AverageType.Median
    let geMean =
        AverageInfo AverageType.GeometricMean

    // Display the dataset elements.
    if ds.Count > 0 then
        printf $"\nDataSet: [{ds[0]}"
        for i = 1 to ds.Count - 1 do
            printf $", {ds[i]}"
        printfn "]\n"

    fmt "Convert." "Default" "Geometric Mean" "Median"
    fmt "--------" "-------" "--------------" "------"
    fmt "ToBoolean"
        (Convert.ToBoolean(ds, null))
        (Convert.ToBoolean(ds, geMean))
        (Convert.ToBoolean(ds, median))
    fmt "ToByte"
        (Convert.ToByte(ds, null))
        (Convert.ToByte(ds, geMean))
        (Convert.ToByte(ds, median))
    fmt "ToChar"
        (Convert.ToChar(ds, null))
        (Convert.ToChar(ds, geMean))
        (Convert.ToChar(ds, median))
    printfn $"""{"ToDateTime",-12}{Convert.ToDateTime(ds, null).ToString "20:yyyy-MM-dd HH:mm:ss"}{Convert.ToDateTime(ds, geMean).ToString "20:yyyy-MM-dd HH:mm:ss"}{Convert.ToDateTime(ds, median).ToString "20:yyyy-MM-dd HH:mm:ss"}"""

    fmt "ToDecimal"
        (Convert.ToDecimal(ds, null))
        (Convert.ToDecimal(ds, geMean))
        (Convert.ToDecimal(ds, median))
    fmt "ToDouble"
        (Convert.ToDouble(ds, null))
        (Convert.ToDouble(ds, geMean))
        (Convert.ToDouble(ds, median))
    fmt "ToInt16"
        (Convert.ToInt16(ds, null))
        (Convert.ToInt16(ds, geMean))
        (Convert.ToInt16(ds, median))
    fmt "ToInt32"
        (Convert.ToInt32(ds, null))
        (Convert.ToInt32(ds, geMean))
        (Convert.ToInt32(ds, median))
    fmt "ToInt64"
        (Convert.ToInt64(ds, null))
        (Convert.ToInt64(ds, geMean))
        (Convert.ToInt64(ds, median))
    fmt "ToSByte"
        (Convert.ToSByte(ds, null))
        (Convert.ToSByte(ds, geMean))
        (Convert.ToSByte(ds, median))
    fmt "ToSingle"
        (Convert.ToSingle(ds, null))
        (Convert.ToSingle(ds, geMean))
        (Convert.ToSingle(ds, median))
    fmt "ToUInt16"
        (Convert.ToUInt16(ds, null))
        (Convert.ToUInt16(ds, geMean))
        (Convert.ToUInt16(ds, median))
    fmt "ToUInt32"
        (Convert.ToUInt32(ds, null))
        (Convert.ToUInt32(ds, geMean))
        (Convert.ToUInt32(ds, median))
    fmt "ToUInt64"
        (Convert.ToUInt64(ds, null))
        (Convert.ToUInt64(ds, geMean))
        (Convert.ToUInt64(ds, median))

printfn
    """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.
"""

let ds1 = DataSet(10.5, 22.2, 45.9, 88.7, 156.05, 297.6)
displayDataSet ds1

let ds2 = 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

Poznámky

Návratová hodnota je výsledkem vyvolání IConvertible.ToDouble metody základního valuetypu .

provider umožňuje uživateli zadat informace o převodu specifické pro jazykovou verzi obsahu nástroje value. Pokud value například představuje String číslo, provider může poskytnout informace specifické pro jazykovou verzi o zápisu použitém k reprezentaci daného čísla.

Základní typy ignorují provider, ale parametr může být použit, pokud value je uživatelem definovaný typ, který implementuje IConvertible rozhraní.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::UInt64 value);

[System.CLSCompliant(false)]
public static double ToDouble (ulong value);

[<System.CLSCompliant(false)>]
static member ToDouble : uint64 -> double

Public Shared Function ToDouble (value As ULong) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Atributy

CLSCompliantAttribute

Příklady

Následující příklad převede každý prvek v poli UInt64 hodnot na Double hodnotu.

ulong[] numbers = { UInt64.MinValue, 121, 12345, UInt64.MaxValue };
double result;

foreach (ulong number in numbers)
{
   result = Convert.ToDouble(number);
   Console.WriteLine("Converted the UInt64 value {0} to {1}.",
                     number, result);
}
// The example displays the following output:
//    Converted the UInt64 value 0 to 0.
//    Converted the UInt64 value 121 to 121.
//    Converted the UInt64 value 12345 to 12345.
//    Converted the UInt64 value 18446744073709551615 to 1.84467440737096E+19.

let numbers =
    [| UInt64.MinValue; 121uL; 12345uL; UInt64.MaxValue |]

for number in numbers do
    let result = Convert.ToDouble number
    printfn $"Converted the UInt64 value {number} to {result}."
// The example displays the following output:
//    Converted the UInt64 value 0 to 0.
//    Converted the UInt64 value 121 to 121.
//    Converted the UInt64 value 12345 to 12345.
//    Converted the UInt64 value 18446744073709551615 to 1.84467440737096E+19.

Dim numbers() As ULong = { UInt64.MinValue, 121, 12345, UInt64.MaxValue }
Dim result As Double

For Each number As ULong In numbers
   result = Convert.ToDouble(number)
   Console.WriteLine("Converted the UInt64 value {0} to {1}.", _
                     number, result)
Next   
' The example displays the following output:
'    Converted the UInt64 value 0 to 0.
'    Converted the UInt64 value 121 to 121.
'    Converted the UInt64 value 12345 to 12345.
'    Converted the UInt64 value 18446744073709551615 to 1.84467440737096E+19.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::UInt32 value);

[System.CLSCompliant(false)]
public static double ToDouble (uint value);

[<System.CLSCompliant(false)>]
static member ToDouble : uint32 -> double

Public Shared Function ToDouble (value As UInteger) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Atributy

CLSCompliantAttribute

Příklady

Následující příklad převede každý prvek v poli UInt32 hodnot na Double hodnotu.

uint[] numbers = { UInt32.MinValue, 121, 12345, UInt32.MaxValue };
double result;

foreach (uint number in numbers)
{
   result = Convert.ToDouble(number);
   Console.WriteLine("Converted the UInt32 value {0} to {1}.",
                     number, result);
}
// The example displays the following output:
//       Converted the UInt32 value 0 to 0.
//       Converted the UInt32 value 121 to 121.
//       Converted the UInt32 value 12345 to 12345.
//       Converted the UInt32 value 4294967295 to 4294967295.

let numbers =
    [| UInt32.MinValue; 121u; 12345u; UInt32.MaxValue |]

for number in numbers do
    let result = Convert.ToDouble number
    printfn $"Converted the UInt32 value {number} to {result}."
// The example displays the following output:
//       Converted the UInt32 value 0 to 0.
//       Converted the UInt32 value 121 to 121.
//       Converted the UInt32 value 12345 to 12345.
//       Converted the UInt32 value 4294967295 to 4294967295.

Dim numbers() As UInteger = { UInt32.MinValue, 121, 12345, UInt32.MaxValue }
Dim result As Double

For Each number As UInteger In numbers
   result = Convert.ToDouble(number)
   Console.WriteLine("Converted the UInt32 value {0} to {1}.", _
                     number, result)
Next   
' The example displays the following output:
'       Converted the UInt32 value 0 to 0.
'       Converted the UInt32 value 121 to 121.
'       Converted the UInt32 value 12345 to 12345.
'       Converted the UInt32 value 4294967295 to 4294967295.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::UInt16 value);

[System.CLSCompliant(false)]
public static double ToDouble (ushort value);

[<System.CLSCompliant(false)>]
static member ToDouble : uint16 -> double

Public Shared Function ToDouble (value As UShort) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Atributy

CLSCompliantAttribute

Příklady

Následující příklad převede každý prvek v poli UInt16 hodnot na Double hodnotu.

ushort[] numbers = { UInt16.MinValue, 121, 12345, UInt16.MaxValue };
double result;

foreach (ushort number in numbers)
{
   result = Convert.ToDouble(number);
   Console.WriteLine("Converted the UInt16 value {0} to {1}.",
                     number, result);
}
// The example displays the following output:
//       Converted the UInt16 value 0 to 0.
//       Converted the UInt16 value 121 to 121.
//       Converted the UInt16 value 12345 to 12345.
//       Converted the UInt16 value 65535 to 65535.

let numbers = 
    [| UInt16.MinValue; 121us; 12345us; UInt16.MaxValue |]

for number in numbers do
    let result = Convert.ToDouble number
    printfn $"Converted the UInt16 value {number} to {result}."
// The example displays the following output:
//       Converted the UInt16 value 0 to 0.
//       Converted the UInt16 value 121 to 121.
//       Converted the UInt16 value 12345 to 12345.
//       Converted the UInt16 value 65535 to 65535.

Dim numbers() As UShort = { UInt16.MinValue, 121, 12345, UInt16.MaxValue }
Dim result As Double

For Each number As UShort In numbers
   result = Convert.ToDouble(number)
   Console.WriteLine("Converted the UInt16 value {0} to {1}.", _
                     number, result)
Next   
' The example displays the following output:
'       Converted the UInt16 value 0 to 0.
'       Converted the UInt16 value 121 to 121.
'       Converted the UInt16 value 12345 to 12345.
'       Converted the UInt16 value 65535 to 65535.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::String ^ value, IFormatProvider ^ provider);

public static double ToDouble (string value, IFormatProvider provider);

public static double ToDouble (string? value, IFormatProvider? provider);

static member ToDouble : string * IFormatProvider -> double

Public Shared Function ToDouble (value As String, provider As IFormatProvider) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu v value, nebo 0 (nula), pokud value je null.

Výjimky

Příklady

Následující příklad převede řetězcové Double reprezentace hodnot pomocí ToDouble metody pomocí objektu IFormatProvider .

using System;
using System.Globalization;

class Example
{
    static void Main()
    {
        // Create a NumberFormatInfo object and set some of its properties.
        NumberFormatInfo provider = new NumberFormatInfo();
        provider.NumberDecimalSeparator = ",";
        provider.NumberGroupSeparator = ".";
        provider.NumberGroupSizes = new int[] { 3 };

        // Define an array of numeric strings to convert.
        String[] values = { "123456789", "12345.6789", "12345,6789",
                            "123,456.789", "123.456,789",
                            "123,456,789.0123", "123.456.789,0123" };

        Console.WriteLine("Default Culture: {0}\n",
                          CultureInfo.CurrentCulture.Name);
        Console.WriteLine("{0,-22} {1,-20} {2,-20}\n", "String to Convert",
                          "Default/Exception", "Provider/Exception");

        // Convert each string to a Double with and without the provider.
        foreach (var value in values) {
           Console.Write("{0,-22} ", value);
           try {
              Console.Write("{0,-20} ", Convert.ToDouble(value));
           }
           catch (FormatException e) {
              Console.Write("{0,-20} ", e.GetType().Name);
           }
           try {
              Console.WriteLine("{0,-20} ", Convert.ToDouble(value, provider));
           }
           catch (FormatException e) {
              Console.WriteLine("{0,-20} ", e.GetType().Name);
           }
        }
    }
}
// The example displays the following output:
//       Default Culture: en-US
//
//       String to Convert      Default/Exception    Provider/Exception
//
//       123456789              123456789            123456789
//       12345.6789             12345.6789           123456789
//       12345,6789             123456789            12345.6789
//       123,456.789            123456.789           FormatException
//       123.456,789            FormatException      123456.789
//       123,456,789.0123       123456789.0123       FormatException
//       123.456.789,0123       FormatException      123456789.0123

open System
open System.Globalization

// Create a NumberFormatInfo object and set some of its properties.
let provider =
    NumberFormatInfo(NumberDecimalSeparator = ",", NumberGroupSeparator = ".", NumberGroupSizes = [| 3 |])

// Define an array of numeric strings to convert.
let values =
    [| "123456789"
       "12345.6789"
       "12345,6789"
       "123,456.789"
       "123.456,789"
       "123,456,789.0123"
       "123.456.789,0123" |]

printfn $"Default Culture: {CultureInfo.CurrentCulture.Name}\n"
printfn $"""{"String to Convert", -22} {"Default/Exception", -20} {"Provider/Exception", -20}\n"""

// Convert each string to a Double with and without the provider.
for value in values do
    printf $"{value, -22} "

    try
        printf $"{Convert.ToDouble value, -20} "
    with :? FormatException as e -> printf $"{e.GetType().Name, -20} "

    try
        printfn $"{Convert.ToDouble(value, provider), -20} "
    with :? FormatException as e -> printfn $"{e.GetType().Name, -20} "
// The example displays the following output:
//       Default Culture: en-US
//
//       String to Convert      Default/Exception    Provider/Exception
//
//       123456789              123456789            123456789
//       12345.6789             12345.6789           123456789
//       12345,6789             123456789            12345.6789
//       123,456.789            123456.789           FormatException
//       123.456,789            FormatException      123456.789
//       123,456,789.0123       123456789.0123       FormatException
//       123.456.789,0123       FormatException      123456789.0123

Imports System.Globalization

Module Example
    Sub Main()
        ' Create a NumberFormatInfo object and set some of its properties.
        Dim provider As New NumberFormatInfo() 
        provider.NumberDecimalSeparator = ","
        provider.NumberGroupSeparator = "."
        provider.NumberGroupSizes = { 3 }

        ' Define an array of numeric strings to convert.
        Dim values() As String = { "123456789", "12345.6789", "12345,6789", 
                                   "123,456.789", "123.456,789", 
                                   "123,456,789.0123", "123.456.789,0123" }

        Console.WriteLine("Default Culture: {0}", 
                          CultureInfo.CurrentCulture.Name)
        Console.WriteLine()                          
        Console.WriteLine("{0,-22} {1,-20} {2,-20}", "String to Convert",
                          "Default/Exception", "Provider/Exception")
        Console.WriteLine()
        ' Convert each string to a Double with and without the provider.
        For Each value In values
           Console.Write("{0,-22} ", value)
           Try
              Console.Write("{0,-20} ", Convert.ToDouble(value))
           Catch e As FormatException
              Console.Write("{0,-20} ", e.GetType().Name)
           End Try
           Try
              Console.WriteLine("{0,-20} ", Convert.ToDouble(value, provider))
           Catch e As FormatException
              Console.WriteLine("{0,-20} ", e.GetType().Name)
           End Try
        Next
    End Sub 
End Module 
' The example displays the following output:
'       Default Culture: en-US
'       
'       String to Convert      Default/Exception    Provider/Exception
'       
'       123456789              123456789            123456789
'       12345.6789             12345.6789           123456789
'       12345,6789             123456789            12345.6789
'       123,456.789            123456.789           FormatException
'       123.456,789            FormatException      123456.789
'       123,456,789.0123       123456789.0123       FormatException
'       123.456.789,0123       FormatException      123456789.0123

Poznámky

Návratová hodnota je výsledkem vyvolání metody na Double.Parsevalue.

provider IFormatProvider je instance, která získá NumberFormatInfo objekt. Objekt NumberFormatInfo poskytuje informace specifické pro jazykovou verzi valueformátu . Pokud provider je null, použije se NumberFormatInfo pro aktuální jazykovou verzi.

Pokud nechcete zpracovávat výjimku v případě selhání převodu, můžete místo toho volat metodu Double.TryParse . Vrátí Boolean hodnotu, která označuje, zda byl převod úspěšný nebo neúspěšný.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(float value);

public static double ToDouble (float value);

static member ToDouble : single -> double

Public Shared Function ToDouble (value As Single) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Příklady

Následující příklad převede Single hodnotu na Double hodnotu.

public:
   void CovertDoubleFloat( double doubleVal )
   {
      float floatVal = 0;
      
      // A conversion from Double to Single cannot overflow.
      floatVal = System::Convert::ToSingle( doubleVal );
      System::Console::WriteLine( " {0} as a float is {1}",
                                  doubleVal, floatVal );

      // A conversion from Single to Double cannot overflow.
      doubleVal = System::Convert::ToDouble( floatVal );
      System::Console::WriteLine( " {0} as a double is: {1}",
                                  floatVal, doubleVal );
   }

public void CovertDoubleFloat(double doubleVal) {	
    float floatVal = 0;

    // Double to float conversion cannot overflow.
        floatVal = System.Convert.ToSingle(doubleVal);
        System.Console.WriteLine("{0} as a float is {1}",
            doubleVal, floatVal);

    // Conversion from float to double cannot overflow.
    doubleVal = System.Convert.ToDouble(floatVal);
    System.Console.WriteLine("{0} as a double is: {1}",
        floatVal, doubleVal);
}

let covertDoubleFloat (doubleVal: float) =
    // Double to float conversion cannot overflow.
    let floatVal = Convert.ToSingle doubleVal
    printfn $"{doubleVal} as a float is {floatVal}"

    // Conversion from float to double cannot overflow.
    let doubleVal = Convert.ToDouble floatVal
    printfn $"{floatVal} as a double is: {doubleVal}"

Public Sub CovertDoubleFloat(ByVal doubleVal As Double)
    Dim singleVal As Single = 0

    ' Double to Single conversion cannot overflow.
        singleVal = System.Convert.ToSingle(doubleVal)
        System.Console.WriteLine("{0} as a Single is {1}", _
                                  doubleVal, singleVal)

    ' Conversion from Single to Double cannot overflow.
    doubleVal = System.Convert.ToDouble(singleVal)
    System.Console.WriteLine("{0} as a Double is: {1}", _
                              singleVal, doubleVal)
End Sub

Viz také

• Single

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::SByte value);

[System.CLSCompliant(false)]
public static double ToDouble (sbyte value);

[<System.CLSCompliant(false)>]
static member ToDouble : sbyte -> double

Public Shared Function ToDouble (value As SByte) As Double

Parametry

Návraty

8bitové celé číslo se signoumm sadou, které je ekvivalentní k value.

Atributy

CLSCompliantAttribute

Příklady

Následující příklad převede každý prvek v poli SByte hodnot na Double hodnotu.

sbyte[] numbers = { SByte.MinValue, -23, 0, 17, SByte.MaxValue };
double result;

foreach (sbyte number in numbers)
{
   result = Convert.ToDouble(number);
   Console.WriteLine("Converted the SByte value {0} to {1}.", number, result);
}
//       Converted the SByte value -128 to -128.
//       Converted the SByte value -23 to -23.
//       Converted the SByte value 0 to 0.
//       Converted the SByte value 17 to 17.
//       Converted the SByte value 127 to 127.

let numbers = 
    [| SByte.MinValue; -23y; 0y; 17y; SByte.MaxValue |]

for number in numbers do
    let result = Convert.ToDouble number
    printfn $"Converted the SByte value {number} to {result}."
//       Converted the SByte value -128 to -128.
//       Converted the SByte value -23 to -23.
//       Converted the SByte value 0 to 0.
//       Converted the SByte value 17 to 17.
//       Converted the SByte value 127 to 127.

Dim numbers() As SByte = { SByte.MinValue, -23, 0, 17, SByte.MaxValue }
Dim result As Double

For Each number As SByte In numbers
   result = Convert.ToDouble(number)
   Console.WriteLine("Converted the SByte value {0} to {1}.", number, result)
Next
'       Converted the SByte value -128 to -128.
'       Converted the SByte value -23 to -23.
'       Converted the SByte value 0 to 0.
'       Converted the SByte value 17 to 17.
'       Converted the SByte value 127 to 127.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::Object ^ value);

public static double ToDouble (object value);

public static double ToDouble (object? value);

static member ToDouble : obj -> double

Public Shared Function ToDouble (value As Object) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá value, nebo nula, pokud value je null.

Výjimky

Příklady

Následující příklad se pokusí převést každou hodnotu v poli objektů na Double.

object[] values = { true, 'a', 123, 1.764e32f, "9.78", "1e-02",
                    1.67e03f, "A100", "1,033.67", DateTime.Now,
                    Decimal.MaxValue };
double result;

foreach (object value in values)
{
   try {
      result = Convert.ToDouble(value);
      Console.WriteLine("Converted the {0} value {1} to {2}.",
                        value.GetType().Name, value, result);
   }
   catch (FormatException) {
      Console.WriteLine("The {0} value {1} is not recognized as a valid Double value.",
                        value.GetType().Name, value);
   }
   catch (InvalidCastException) {
      Console.WriteLine("Conversion of the {0} value {1} to a Double is not supported.",
                        value.GetType().Name, value);
   }
}
// The example displays the following output:
//    Converted the Boolean value True to 1.
//    Conversion of the Char value a to a Double is not supported.
//    Converted the Int32 value 123 to 123.
//    Converted the Single value 1.764E+32 to 1.76399995098587E+32.
//    Converted the String value 9.78 to 9.78.
//    Converted the String value 1e-02 to 0.01.
//    Converted the Single value 1670 to 1670.
//    The String value A100 is not recognized as a valid Double value.
//    Converted the String value 1,033.67 to 1033.67.
//    Conversion of the DateTime value 10/21/2008 07:12:12 AM to a Double is not supported.
//    Converted the Decimal value 79228162514264337593543950335 to 7.92281625142643E+28.

let values: obj[] =
    [| true; 'a'; 123; 1.764e32f; "9.78"; "1e-02";
       1.67e03f; "A100"; "1,033.67"; DateTime.Now
       Decimal.MaxValue |]

for value in values do
    try
        let result = Convert.ToDouble value
        printfn $"Converted the {value.GetType().Name} value {value} to {result}."
    with
    | :? FormatException ->
        printfn $"The {value.GetType().Name} value {value} is not recognized as a valid Double value."
    | :? InvalidCastException ->
        printfn $"Conversion of the {value.GetType().Name} value {value} to a Double is not supported."
// The example displays the following output:
//    Converted the Boolean value True to 1.
//    Conversion of the Char value a to a Double is not supported.
//    Converted the Int32 value 123 to 123.
//    Converted the Single value 1.764E+32 to 1.76399995098587E+32.
//    Converted the String value 9.78 to 9.78.
//    Converted the String value 1e-02 to 0.01.
//    Converted the Single value 1670 to 1670.
//    The String value A100 is not recognized as a valid Double value.
//    Converted the String value 1,033.67 to 1033.67.
//    Conversion of the DateTime value 10/21/2008 07:12:12 AM to a Double is not supported.
//    Converted the Decimal value 79228162514264337593543950335 to 7.92281625142643E+28.

Dim values() As Object = { True, "a"c, 123, CSng(1.764e32), "9.78", "1e-02", _
                           CSng(1.67e03), "A100", "1,033.67", Date.Now, _
                           Decimal.MaxValue }   
Dim result As Double

For Each value As Object In values
   Try
      result = Convert.ToDouble(value)
      Console.WriteLine("Converted the {0} value {1} to {2}.", _
                        value.GetType().Name, value, result)
   Catch e As FormatException
      Console.WriteLine("The {0} value {1} is not recognized as a valid Double value.", _
                        value.GetType().Name, value)
   Catch e As InvalidCastException
      Console.WriteLine("Conversion of the {0} value {1} to a Double is not supported.", _
                        value.GetType().Name, value)
   End Try                     
Next
' The example displays the following output:
'    Converted the Boolean value True to 1.
'    Conversion of the Char value a to a Double is not supported.
'    Converted the Int32 value 123 to 123.
'    Converted the Single value 1.764E+32 to 1.76399995098587E+32.
'    Converted the String value 9.78 to 9.78.
'    Converted the String value 1e-02 to 0.01.
'    Converted the Single value 1670 to 1670.
'    The String value A100 is not recognized as a valid Double value.
'    Converted the String value 1,033.67 to 1033.67.
'    Conversion of the DateTime value 10/21/2008 07:12:12 AM to a Double is not supported.
'    Converted the Decimal value 79228162514264337593543950335 to 7.92281625142643E+28.

Poznámky

Pokud value není null, tato metoda zabalí volání IConvertible.ToDouble implementace základního valuetypu .

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::String ^ value);

public static double ToDouble (string value);

public static double ToDouble (string? value);

static member ToDouble : string -> double

Public Shared Function ToDouble (value As String) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu v value, nebo 0 (nula), pokud value je null.

Výjimky

Příklady

Následující příklad se pokusí převést každý prvek v poli číselných řetězců na Double. Výstup příkladu je ze systému, jehož aktuální jazyková verze je en-US.

using System;

public class Example
{
   public static void Main()
   {
      string[] values= { "-1,035.77219", "1AFF", "1e-35",
                         "1,635,592,999,999,999,999,999,999", "-17.455",
                         "190.34001", "1.29e325"};
      double result;

      foreach (string value in values)
      {
         try {
            result = Convert.ToDouble(value);
            Console.WriteLine("Converted '{0}' to {1}.", value, result);
         }
         catch (FormatException) {
            Console.WriteLine("Unable to convert '{0}' to a Double.", value);
         }
         catch (OverflowException) {
            Console.WriteLine("'{0}' is outside the range of a Double.", value);
         }
      }
   }
}
// The example displays the following output:
//       Converted '-1,035.77219' to -1035.77219.
//       Unable to convert '1AFF' to a Double.
//       Converted '1e-35' to 1E-35.
//       Converted '1,635,592,999,999,999,999,999,999' to 1.635593E+24.
//       Converted '-17.455' to -17.455.
//       Converted '190.34001' to 190.34001.
//       '1.29e325' is outside the range of a Double.

open System

let values= 
    [| "-1,035.77219"; "1AFF"; "1e-35"
       "1,635,592,999,999,999,999,999,999"; "-17.455"
       "190.34001"; "1.29e325" |]

for value in values do
    try
        let result = Convert.ToDouble value
        printfn $"Converted '{value}' to {result}."
    with
    | :? FormatException ->
        printfn $"Unable to convert '{value}' to a Double."
    | :? OverflowException ->
        printfn $"'{value}' is outside the range of a Double."
// The example displays the following output:
//       Converted '-1,035.77219' to -1035.77219.
//       Unable to convert '1AFF' to a Double.
//       Converted '1e-35' to 1E-35.
//       Converted '1,635,592,999,999,999,999,999,999' to 1.635593E+24.
//       Converted '-17.455' to -17.455.
//       Converted '190.34001' to 190.34001.
//       '1.29e325' is outside the range of a Double.

Module Example
   Public Sub Main()
      Dim values() As String = { "-1,035.77219", "1AFF", "1e-35", _
                                 "1,635,592,999,999,999,999,999,999", "-17.455", _
                                 "190.34001", "1.29e325"}
      Dim result As Double
      
      For Each value As String In values
         Try
            result = Convert.ToDouble(value)
            Console.WriteLine("Converted '{0}' to {1}.", value, result)
         Catch e As FormatException
            Console.WriteLine("Unable to convert '{0}' to a Double.", value)            
         Catch e As OverflowException
            Console.WriteLine("'{0}' is outside the range of a Double.", value)
         End Try
      Next       
   End Sub   
End Module
' The example displays the following output:
'       Converted '-1,035.77219' to -1035.77219.
'       Unable to convert '1AFF' to a Double.
'       Converted '1e-35' to 1E-35.
'       Converted '1,635,592,999,999,999,999,999,999' to 1.635593E+24.
'       Converted '-17.455' to -17.455.
'       Converted '190.34001' to 190.34001.
'       '1.29e325' is outside the range of a Double.

Poznámky

ToDouble(String) Použití metody je ekvivalentem předání value metoděDouble.Parse(String). value se interpretuje pomocí konvencí formátování aktuální jazykové verze.

Pokud nechcete zpracovávat výjimku v případě selhání převodu, můžete místo toho volat metodu Double.TryParse . Vrátí Boolean hodnotu, která označuje, zda byl převod úspěšný nebo neúspěšný.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(int value);

public static double ToDouble (int value);

static member ToDouble : int -> double

Public Shared Function ToDouble (value As Integer) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Příklady

Následující příklad převede Int32 hodnotu na Double hodnotu.

public:
   void ConvertDoubleInt( double doubleVal )
   {
      int intVal = 0;
      
      // Double to int conversion can overflow.
      try
      {
         intVal = System::Convert::ToInt32( doubleVal );
         System::Console::WriteLine( " {0} as an int is: {1}",
         doubleVal, intVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine( "Overflow in double-to-int conversion." );
      }
      
      // Int to double conversion cannot overflow.
      doubleVal = System::Convert::ToDouble( intVal );
      System::Console::WriteLine( " {0} as a double is: {1}",
         intVal, doubleVal );
   }

public void ConvertDoubleInt(double doubleVal) {
    
    int     intVal = 0;
    // Double to int conversion can overflow.
    try {
        intVal = System.Convert.ToInt32(doubleVal);
        System.Console.WriteLine("{0} as an int is: {1}",
            doubleVal, intVal);
    }
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "Overflow in double-to-int conversion.");
    }

    // Int to double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(intVal);
    System.Console.WriteLine("{0} as a double is: {1}",
        intVal, doubleVal);
}

let convertDoubleInt (doubleVal: float) = 
    let intVal = 0
    // Double to int conversion can overflow.
    try
        let intVal = Convert.ToInt32 doubleVal
        printfn $"{doubleVal} as an int is: {intVal}"
    with :? OverflowException ->
        printfn "Overflow in double-to-int conversion."

    // Int to double conversion cannot overflow.
    let doubleVal = Convert.ToDouble intVal
    printfn $"{intVal} as a double is: {doubleVal}"

Public Sub ConvertDoubleInt(ByVal doubleVal As Double)

    Dim intVal As Integer = 0
    ' Double to Integer conversion can overflow.
    Try
        intVal = System.Convert.ToInt32(doubleVal)
        System.Console.WriteLine("{0} as an Integer is: {1}", _
                                  doubleVal, intVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in Double-to-Byte conversion.")
    End Try

    ' Integer to Double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(intVal)
    System.Console.WriteLine("{0} as a Double is: {1}", _
                              intVal, doubleVal)
End Sub

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(short value);

public static double ToDouble (short value);

static member ToDouble : int16 -> double

Public Shared Function ToDouble (value As Short) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá value.

Příklady

Následující příklad převede každý prvek v poli 16bitových 16bitových celých signedch Double .

short[] numbers = { Int16.MinValue, -1032, 0, 192, Int16.MaxValue };
double result;

foreach (short number in numbers)
{
   result = Convert.ToDouble(number);
   Console.WriteLine("Converted the UInt16 value {0} to {1}.",
                     number, result);
}
//       Converted the UInt16 value -32768 to -32768.
//       Converted the UInt16 value -1032 to -1032.
//       Converted the UInt16 value 0 to 0.
//       Converted the UInt16 value 192 to 192.
//       Converted the UInt16 value 32767 to 32767.

let numbers = 
    [| Int16.MinValue; -1032s; 0s; 192s; Int16.MaxValue |]

for number in numbers do
    let result = Convert.ToDouble number
    printfn $"Converted the UInt16 value {number} to {result}."
// The example displays the following output:
//       Converted the UInt16 value -32768 to -32768.
//       Converted the UInt16 value -1032 to -1032.
//       Converted the UInt16 value 0 to 0.
//       Converted the UInt16 value 192 to 192.
//       Converted the UInt16 value 32767 to 32767.

Dim numbers() As Short = { Int16.MinValue, -1032, 0, 192, Int16.MaxValue }
Dim result As Double

For Each number As Short In numbers
   result = Convert.ToDouble(number)
   Console.WriteLine("Converted the UInt16 value {0} to {1}.", _
                     number, result)
Next                     
'       Converted the UInt16 value -32768 to -32768.
'       Converted the UInt16 value -1032 to -1032.
'       Converted the UInt16 value 0 to 0.
'       Converted the UInt16 value 192 to 192.
'       Converted the UInt16 value 32767 to 32767.

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(double value);

public static double ToDouble (double value);

static member ToDouble : double -> double

Public Shared Function ToDouble (value As Double) As Double

Parametry

Návraty

value se vrátí beze změny.

Viz také

• Double

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::Decimal value);

public static double ToDouble (decimal value);

static member ToDouble : decimal -> double

Public Shared Function ToDouble (value As Decimal) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Příklady

Následující příklad převede Decimal hodnotu na Double hodnotu.

public:
   void ConvertDoubleDecimal( double doubleVal )
   {
      Decimal decimalVal;
      
      // Conversion from double to decimal cannot overflow.
      decimalVal = System::Convert::ToDecimal( doubleVal );
      System::Console::WriteLine( " {0} as a decimal is: {1}",
         doubleVal, decimalVal );
      
      // Decimal to double conversion can overflow.
      try
      {
         doubleVal = System::Convert::ToDouble( decimalVal );
         System::Console::WriteLine( " {0} as a double is: {1}",
         decimalVal, doubleVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine( "Overflow in decimal-to-double conversion." );
      }
   }

public void ConvertDoubleDecimal(decimal decimalVal){
    
    double doubleVal;
    
    // Decimal to double conversion cannot overflow.
 doubleVal = System.Convert.ToDouble(decimalVal);
    System.Console.WriteLine("{0} as a double is: {1}",
            decimalVal, doubleVal);

    // Conversion from double to decimal can overflow.
    try
 {
       decimalVal = System.Convert.ToDecimal(doubleVal);
    System.Console.WriteLine ("{0} as a decimal is: {1}",
        doubleVal, decimalVal);
    }
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "Overflow in double-to-double conversion.");
    }
}

let convertDoubleDecimal (decimalVal: float) =
    // Decimal to double conversion cannot overflow.
    let doubleVal = 
        Convert.ToDouble decimalVal
    printfn $"{decimalVal} as a double is: {doubleVal}"

    // Conversion from double to decimal can overflow.
    try
        let decimalVal = Convert.ToDecimal doubleVal
        printfn $"{doubleVal} as a decimal is: {decimalVal}"
    with :? OverflowException ->
        printfn "Overflow in double-to-double conversion."

Public Sub ConvertDoubleDecimal(ByVal decimalVal As Decimal)

    Dim doubleVal As Double

    ' Decimal to Double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(decimalVal)
    System.Console.WriteLine("{0} as a Double is: {1}", _
                             decimalVal, doubleVal)
    
    ' Conversion from Double to Decimal can overflow.
    Try
       decimalVal = System.Convert.ToDecimal(doubleVal)
       System.Console.WriteLine("{0} as a Decimal is: {1}", _
                                doubleVal, decimalVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in Double-to-Decimal conversion.")
    End Try

End Sub

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(DateTime value);

public static double ToDouble (DateTime value);

static member ToDouble : DateTime -> double

Public Shared Function ToDouble (value As DateTime) As Double

Parametry

Návraty

Tento převod není podporován. Není vrácena žádná hodnota.

Výjimky

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(char value);

public static double ToDouble (char value);

static member ToDouble : char -> double

Public Shared Function ToDouble (value As Char) As Double

Parametry

Návraty

Tento převod není podporován. Není vrácena žádná hodnota.

Výjimky

Viz také

• Char

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(System::Byte value);

public static double ToDouble (byte value);

static member ToDouble : byte -> double

Public Shared Function ToDouble (value As Byte) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Příklady

Následující příklad převede Byte hodnotu na Double hodnotu.

public:
   void ConvertDoubleByte( double doubleVal )
   {
      Byte byteVal = 0;
      
      // Double to Byte conversion can overflow.
      try
      {
         byteVal = System::Convert::ToByte( doubleVal );
         System::Console::WriteLine( " {0} as a Byte is: {1}.",
         doubleVal, byteVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine( "Overflow in double-to-Byte conversion." );
      }
      
      // Byte to double conversion cannot overflow.
      doubleVal = System::Convert::ToDouble( byteVal );
      System::Console::WriteLine( " {0} as a double is: {1}.",
         byteVal, doubleVal );
   }

public void ConvertDoubleByte(double doubleVal) {
    byte	byteVal = 0;

    // Double to byte conversion can overflow.
    try {
        byteVal = System.Convert.ToByte(doubleVal);
        System.Console.WriteLine("{0} as a byte is: {1}.",
            doubleVal, byteVal);
    }
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "Overflow in double-to-byte conversion.");
    }

    // Byte to double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(byteVal);
    System.Console.WriteLine("{0} as a double is: {1}.",
        byteVal, doubleVal);
}

let convertDoubleByte (doubleVal: float) =
    // Double to byte conversion can overflow.
    try
        let byteVal = Convert.ToByte doubleVal
        printfn $"{doubleVal} as a byte is: {byteVal}."
        
        // Byte to double conversion cannot overflow.
        let doubleVal = Convert.ToDouble byteVal
        printfn $"{byteVal} as a double is: {doubleVal}."
    with :? OverflowException ->
        printfn "Overflow in double-to-byte conversion."

Public Sub ConvertDoubleByte(ByVal doubleVal As Double)
    Dim byteVal As Byte = 0

    ' Double to Byte conversion can overflow.
    Try
        byteVal = System.Convert.ToByte(doubleVal)
        System.Console.WriteLine("{0} as a Byte is: {1}.", _
            doubleVal, byteVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in Double-to-Byte conversion.")
    End Try

    ' Byte to Double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(byteVal)
    System.Console.WriteLine("{0} as a Double is: {1}.", _
                              byteVal, doubleVal)
End Sub

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(bool value);

public static double ToDouble (bool value);

static member ToDouble : bool -> double

Public Shared Function ToDouble (value As Boolean) As Double

Parametry

Návraty

Číslo 1, pokud value je true; v opačném případě 0.

Příklady

Následující příklad převede Boolean hodnotu na Double hodnotu.

public:
   void ConvertDoubleBool( double doubleVal )
   {
      bool boolVal;
      
      // Double to bool conversion cannot overflow.
      boolVal = System::Convert::ToBoolean( doubleVal );
      System::Console::WriteLine( " {0} as a Boolean is: {1}.",
         doubleVal, boolVal );
      
      // bool to double conversion cannot overflow.
      doubleVal = System::Convert::ToDouble( boolVal );
      System::Console::WriteLine( " {0} as a double is: {1}.",
         boolVal, doubleVal );
   }

public void ConvertDoubleBool(double doubleVal) {
    bool	boolVal;
    // Double to bool conversion cannot overflow.
    boolVal = System.Convert.ToBoolean(doubleVal);
    System.Console.WriteLine("{0} as a Boolean is: {1}.",
        doubleVal, boolVal);

    // bool to double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(boolVal);
    System.Console.WriteLine("{0} as a double is: {1}.",
        boolVal, doubleVal);
}

let convertDoubleBool (doubleVal: float) =
    // Double to bool conversion cannot overflow.
    let boolVal = Convert.ToBoolean doubleVal
    printfn $"{doubleVal} as a Boolean is: {boolVal}."

    // bool to double conversion cannot overflow.
    let doubleVal = Convert.ToDouble boolVal
    printfn $"{boolVal} as a double is: {doubleVal}."

Public Sub ConvertDoubleBool(ByVal doubleVal As Double)
    Dim boolVal As Boolean

    'Double to Boolean conversion cannot overflow.
    boolVal = System.Convert.ToBoolean(doubleVal)
    System.Console.WriteLine("{0} as a Boolean is: {1}.", _
                              doubleVal, boolVal)

    'Boolean to Double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(boolVal)
    System.Console.WriteLine("{0} as a Double is: {1}.", _
                              boolVal, doubleVal)
End Sub

Zdroj:

Convert.cs

Zdroj:

Convert.cs

Zdroj:

Convert.cs

public:
 static double ToDouble(long value);

public static double ToDouble (long value);

static member ToDouble : int64 -> double

Public Shared Function ToDouble (value As Long) As Double

Parametry

Návraty

Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.

Příklady

Následující příklad převede každý prvek v poli dlouhých celých čísel se signoumi Double hodnotou na hodnotu.

long[] numbers = { Int64.MinValue, -903, 0, 172, Int64.MaxValue};
double result;

foreach (long number in numbers)
{
   result = Convert.ToDouble(number);
   Console.WriteLine("Converted the {0} value '{1}' to the {2} value {3}.",
                     number.GetType().Name, number,
                     result.GetType().Name, result);
}
// The example displays the following output:
//    Converted the Int64 value '-9223372036854775808' to the Double value -9.22337203685478E+18.
//    Converted the Int64 value '-903' to the Double value -903.
//    Converted the Int64 value '0' to the Double value 0.
//    Converted the Int64 value '172' to the Double value 172.
//    Converted the Int64 value '9223372036854775807' to the Double value 9.22337203685478E+18.

let numbers = 
    [| Int64.MinValue; -903L; 0L; 172L; Int64.MaxValue |]

for number in numbers do
    let result = Convert.ToDouble number
    printfn $"Converted the {number.GetType().Name} value '{number}' to the {result.GetType().Name} value {result}."
// The example displays the following output:
//    Converted the Int64 value '-9223372036854775808' to the Double value -9.22337203685478E+18.
//    Converted the Int64 value '-903' to the Double value -903.
//    Converted the Int64 value '0' to the Double value 0.
//    Converted the Int64 value '172' to the Double value 172.
//    Converted the Int64 value '9223372036854775807' to the Double value 9.22337203685478E+18.

Dim numbers() As Long = { Int64.MinValue, -903, 0, 172, Int64.MaxValue}
Dim result As Double

For Each number As Long In numbers
   result = Convert.ToDouble(number)
   Console.WriteLine("Converted the {0} value '{1}' to the {2} value {3}.", _
                     number.GetType().Name, number, _
                     result.GetType().Name, result)

Next
' The example displays the following output:
'    Converted the Int64 value '-9223372036854775808' to the Double value -9.22337203685478E+18.
'    Converted the Int64 value '-903' to the Double value -903.
'    Converted the Int64 value '0' to the Double value 0.
'    Converted the Int64 value '172' to the Double value 172.
'    Converted the Int64 value '9223372036854775807' to the Double value 9.22337203685478E+18.