Convert.ToDouble Metoda
Definice
Důležité
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Převede zadanou hodnotu na číslo s plovoucí desetinou čárkou s dvojitou přesností.
Přetížení
| ToDouble(Object, IFormatProvider) |
Převede hodnotu zadaného objektu na číslo s plovoucí desetinou čárkou s dvojitou přesností pomocí informací formátování specifické pro zadanou jazykovou verzi. |
| ToDouble(UInt64) |
Převede hodnotu zadaného 64bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(UInt32) |
Převede hodnotu zadaného 32bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(UInt16) |
Převede hodnotu zadaného 16bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(String, IFormatProvider) |
Převede zadanou řetězcovou reprezentaci čísla na ekvivalentní číslo s plovoucí desetinnou čárkou s dvojitou přesností pomocí informací o formátování specifické pro zadanou jazykovou verzi. |
| ToDouble(Single) |
Převede hodnotu zadaného čísla s plovoucí desetinou čárkou s jednou přesností na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(SByte) |
Převede hodnotu zadaného 8bitového celočíselného čísla se signoumi sadou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(Object) |
Převede hodnotu zadaného objektu na číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(String) |
Převede zadanou řetězcovou reprezentaci čísla na ekvivalentní číslo s plovoucí desetinnou čárkou s dvojitou přesností. |
| ToDouble(Int32) |
Převede hodnotu zadaného 32bitového celočíselného čísla se signoumi sadou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(Int16) |
Převede hodnotu zadaného 16bitového celočíselného čísla se signoumi adresou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(Double) |
Vrátí zadané číslo s plovoucí desetinou čárkou s dvojitou přesností. neprovádí se žádný skutečný převod. |
| ToDouble(Decimal) |
Převede hodnotu zadaného desetinného čísla na ekvivalentní číslo s plovoucí desetinnou čárkou s dvojitou přesností. |
| ToDouble(DateTime) |
Volání této metody vždy vyvolá InvalidCastException. |
| ToDouble(Char) |
Volání této metody vždy vyvolá InvalidCastException. |
| ToDouble(Byte) |
Převede hodnotu zadaného 8bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(Boolean) |
Převede zadanou logickou hodnotu na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
| ToDouble(Int64) |
Převede hodnotu zadaného 64bitového celočíselného čísla se signoumi sadou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností. |
ToDouble(Object, IFormatProvider)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného objektu na číslo s plovoucí desetinou čárkou s dvojitou přesností pomocí informací formátování specifické pro zadanou jazykovou verzi.
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 -> doublePublic Shared Function ToDouble (value As Object, provider As IFormatProvider) As DoubleParametry
- value
- Object
Objekt, který implementuje IConvertible rozhraní.
- provider
- IFormatProvider
Objekt, který poskytuje informace o formátování specifické pro jazykovou verzi.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá value, nebo nula, pokud value je null.
Výjimky
value není ve vhodném formátu pro typ Double .
value neimplementuje IConvertible rozhraní.
value představuje číslo, které je menší než Double.MinValue nebo větší než Double.MaxValue.
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.
Platí pro
ToDouble(UInt64)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Důležité
Toto rozhraní API neodpovídá specifikaci CLS.
Převede hodnotu zadaného 64bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(System::UInt64 value);[System.CLSCompliant(false)]
public static double ToDouble (ulong value);[<System.CLSCompliant(false)>]
static member ToDouble : uint64 -> doublePublic Shared Function ToDouble (value As ULong) As DoubleParametry
- value
- UInt64
64bitové celé číslo bez znaménka pro převod.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.
- Atributy
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.
Platí pro
ToDouble(UInt32)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Důležité
Toto rozhraní API neodpovídá specifikaci CLS.
Převede hodnotu zadaného 32bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(System::UInt32 value);[System.CLSCompliant(false)]
public static double ToDouble (uint value);[<System.CLSCompliant(false)>]
static member ToDouble : uint32 -> doublePublic Shared Function ToDouble (value As UInteger) As DoubleParametry
- value
- UInt32
32bitové celé číslo bez znaménka pro převod.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.
- Atributy
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.
Platí pro
ToDouble(UInt16)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Důležité
Toto rozhraní API neodpovídá specifikaci CLS.
Převede hodnotu zadaného 16bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(System::UInt16 value);[System.CLSCompliant(false)]
public static double ToDouble (ushort value);[<System.CLSCompliant(false)>]
static member ToDouble : uint16 -> doublePublic Shared Function ToDouble (value As UShort) As DoubleParametry
- value
- UInt16
16bitové celé číslo bez znaménka pro převod.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu value.
- Atributy
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.
Platí pro
ToDouble(String, IFormatProvider)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede zadanou řetězcovou reprezentaci čísla na ekvivalentní číslo s plovoucí desetinnou čárkou s dvojitou přesností pomocí informací o formátování specifické pro zadanou jazykovou verzi.
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 -> doublePublic Shared Function ToDouble (value As String, provider As IFormatProvider) As DoubleParametry
- value
- String
Řetězec obsahující číslo k převedení.
- provider
- IFormatProvider
Objekt, který poskytuje informace o formátování specifické pro jazykovou verzi.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu v value, nebo 0 (nula), pokud value je null.
Výjimky
value není číslo v platném formátu.
value představuje číslo, které je menší než Double.MinValue nebo větší než Double.MaxValue.
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.
Platí pro
ToDouble(Single)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného čísla s plovoucí desetinou čárkou s jednou přesností na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(float value);public static double ToDouble (float value);static member ToDouble : single -> doublePublic Shared Function ToDouble (value As Single) As DoubleParametry
- value
- Single
Číslo s plovoucí desetinou čárkou s jednou přesností.
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
Platí pro
ToDouble(SByte)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Důležité
Toto rozhraní API neodpovídá specifikaci CLS.
Převede hodnotu zadaného 8bitového celočíselného čísla se signoumi sadou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(System::SByte value);[System.CLSCompliant(false)]
public static double ToDouble (sbyte value);[<System.CLSCompliant(false)>]
static member ToDouble : sbyte -> doublePublic Shared Function ToDouble (value As SByte) As DoubleParametry
- value
- SByte
8bitové celé číslo se znaménkem pro převod.
Návraty
8bitové celé číslo se signoumm sadou, které je ekvivalentní k value.
- Atributy
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.
Platí pro
ToDouble(Object)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného objektu na číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(System::Object ^ value);public static double ToDouble (object value);public static double ToDouble (object? value);static member ToDouble : obj -> doublePublic Shared Function ToDouble (value As Object) As DoubleParametry
- value
- Object
Objekt, který implementuje IConvertible rozhraní nebo null.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá value, nebo nula, pokud value je null.
Výjimky
value není ve vhodném formátu pro typ Double .
value představuje číslo, které je menší než Double.MinValue nebo větší než Double.MaxValue.
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 .
Platí pro
ToDouble(String)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede zadanou řetězcovou reprezentaci čísla na ekvivalentní číslo s plovoucí desetinnou čárkou s dvojitou přesností.
public:
static double ToDouble(System::String ^ value);public static double ToDouble (string value);public static double ToDouble (string? value);static member ToDouble : string -> doublePublic Shared Function ToDouble (value As String) As DoubleParametry
- value
- String
Řetězec obsahující číslo k převedení.
Návraty
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které odpovídá číslu v value, nebo 0 (nula), pokud value je null.
Výjimky
value není číslo v platném formátu.
value představuje číslo, které je menší než Double.MinValue nebo větší než Double.MaxValue.
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.
Platí pro
ToDouble(Int32)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného 32bitového celočíselného čísla se signoumi sadou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(int value);public static double ToDouble (int value);static member ToDouble : int -> doublePublic Shared Function ToDouble (value As Integer) As DoubleParametry
- value
- Int32
32bitové celé číslo se znaménkem pro převod.
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
Platí pro
ToDouble(Int16)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného 16bitového celočíselného čísla se signoumi adresou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(short value);public static double ToDouble (short value);static member ToDouble : int16 -> doublePublic Shared Function ToDouble (value As Short) As DoubleParametry
- value
- Int16
16bitové celé číslo se znaménkem pro převod.
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.
Platí pro
ToDouble(Double)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Vrátí zadané číslo s plovoucí desetinou čárkou s dvojitou přesností. neprovádí se žádný skutečný převod.
public:
static double ToDouble(double value);public static double ToDouble (double value);static member ToDouble : double -> doublePublic Shared Function ToDouble (value As Double) As DoubleParametry
- value
- Double
Číslo s plovoucí desetinou čárkou s dvojitou přesností, které se má vrátit.
Návraty
value se vrátí beze změny.
Viz také
Platí pro
ToDouble(Decimal)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného desetinného čísla na ekvivalentní číslo s plovoucí desetinnou čárkou s dvojitou přesností.
public:
static double ToDouble(System::Decimal value);public static double ToDouble (decimal value);static member ToDouble : decimal -> doublePublic Shared Function ToDouble (value As Decimal) As DoubleParametry
- value
- Decimal
Desítkové číslo k převodu.
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
Platí pro
ToDouble(DateTime)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Volání této metody vždy vyvolá InvalidCastException.
public:
static double ToDouble(DateTime value);public static double ToDouble (DateTime value);static member ToDouble : DateTime -> doublePublic Shared Function ToDouble (value As DateTime) As DoubleParametry
- value
- DateTime
Hodnota data a času pro převod.
Návraty
Tento převod není podporován. Není vrácena žádná hodnota.
Výjimky
Tento převod není podporován.
Platí pro
ToDouble(Char)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Volání této metody vždy vyvolá InvalidCastException.
public:
static double ToDouble(char value);public static double ToDouble (char value);static member ToDouble : char -> doublePublic Shared Function ToDouble (value As Char) As DoubleParametry
- value
- Char
Znak Unicode pro převod.
Návraty
Tento převod není podporován. Není vrácena žádná hodnota.
Výjimky
Tento převod není podporován.
Viz také
Platí pro
ToDouble(Byte)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného 8bitového celého čísla bez znaménka na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(System::Byte value);public static double ToDouble (byte value);static member ToDouble : byte -> doublePublic Shared Function ToDouble (value As Byte) As DoubleParametry
- value
- Byte
8bitové celé číslo bez znaménka pro převod.
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
Platí pro
ToDouble(Boolean)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede zadanou logickou hodnotu na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(bool value);public static double ToDouble (bool value);static member ToDouble : bool -> doublePublic Shared Function ToDouble (value As Boolean) As DoubleParametry
- value
- Boolean
Logická hodnota, kterou chcete převést.
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
Platí pro
ToDouble(Int64)
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
- Zdroj:
- Convert.cs
Převede hodnotu zadaného 64bitového celočíselného čísla se signoumi sadou na ekvivalentní číslo s plovoucí desetinou čárkou s dvojitou přesností.
public:
static double ToDouble(long value);public static double ToDouble (long value);static member ToDouble : int64 -> doublePublic Shared Function ToDouble (value As Long) As DoubleParametry
- value
- Int64
64bitové celé číslo se znaménkem pro převod.
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.
Platí pro
Spolupracujte s námi na GitHubu
Zdroj tohoto obsahu najdete na GitHubu, kde můžete také vytvářet a kontrolovat problémy a žádosti o přijetí změn. Další informace najdete v našem průvodci pro přispěvatele.
