Convert.ToDouble 方法
定义
将指定的值转换为双精度浮点数。Converts a specified value to a double-precision floating-point number.
重载
| ToDouble(Object, IFormatProvider) |
使用指定的区域性特定格式设置信息,将指定对象的值转换为双精度浮点数。Converts the value of the specified object to an double-precision floating-point number, using the specified culture-specific formatting information. |
| ToDouble(UInt64) |
将指定的 64 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 64-bit unsigned integer to an equivalent double-precision floating-point number. |
| ToDouble(UInt32) |
将指定的 32 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 32-bit unsigned integer to an equivalent double-precision floating-point number. |
| ToDouble(UInt16) |
将指定的 16 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 16-bit unsigned integer to the equivalent double-precision floating-point number. |
| ToDouble(String) |
将数字的指定字符串表示形式转换为等效的双精度浮点数。Converts the specified string representation of a number to an equivalent double-precision floating-point number. |
| ToDouble(String, IFormatProvider) |
使用指定的区域性特定格式设置信息,将数字的指定字符串表示形式转换为等效的双精度浮点数。Converts the specified string representation of a number to an equivalent double-precision floating-point number, using the specified culture-specific formatting information. |
| ToDouble(SByte) |
将指定的 8 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 8-bit signed integer to the equivalent double-precision floating-point number. |
| ToDouble(Object) |
将指定对象的值转换为双精度浮点数。Converts the value of the specified object to a double-precision floating-point number. |
| ToDouble(Single) |
将指定的单精度浮点数的值转换为等效的双精度浮点数。Converts the value of the specified single-precision floating-point number to an equivalent double-precision floating-point number. |
| ToDouble(Int32) |
将指定的 32 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 32-bit signed integer to an equivalent double-precision floating-point number. |
| ToDouble(Int16) |
将指定的 16 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 16-bit signed integer to an equivalent double-precision floating-point number. |
| ToDouble(Double) |
返回指定的双精度浮点数;不执行任何实际的转换。Returns the specified double-precision floating-point number; no actual conversion is performed. |
| ToDouble(Decimal) |
将指定的十进制数的值转换为等效的双精度浮点数。Converts the value of the specified decimal number to an equivalent double-precision floating-point number. |
| ToDouble(DateTime) |
调用此方法始终引发 InvalidCastException。Calling this method always throws InvalidCastException. |
| ToDouble(Char) |
调用此方法始终引发 InvalidCastException。Calling this method always throws InvalidCastException. |
| ToDouble(Byte) |
将指定的 8 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 8-bit unsigned integer to the equivalent double-precision floating-point number. |
| ToDouble(Boolean) |
将指定的布尔值转换为等效的双精度浮点数。Converts the specified Boolean value to the equivalent double-precision floating-point number. |
| ToDouble(Int64) |
将指定的 64 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 64-bit signed integer to an equivalent double-precision floating-point number. |
ToDouble(Object, IFormatProvider)
使用指定的区域性特定格式设置信息,将指定对象的值转换为双精度浮点数。Converts the value of the specified object to an double-precision floating-point number, using the specified culture-specific formatting information.
public:
static double ToDouble(System::Object ^ value, IFormatProvider ^ provider);
public static double ToDouble (object value, IFormatProvider provider);
public static double ToDouble (object? value, IFormatProvider? provider);
static member ToDouble : obj * IFormatProvider -> double
Public Shared Function ToDouble (value As Object, provider As IFormatProvider) As Double
参数
- value
- Object
一个实现 IConvertible 接口的对象。An object that implements the IConvertible interface.
- provider
- IFormatProvider
一个提供区域性特定的格式设置信息的对象。An object that supplies culture-specific formatting information.
返回
与 value 等效的双精度浮点数,如果 value 为 null,则为零。A double-precision floating-point number that is equivalent to value, or zero if value is null.
例外
value 不实现 IConvertible 接口。value does not implement the IConvertible interface.
value 表示一个小于 MinValue 或大于 MaxValue 的数字。value represents a number that is less than MinValue or greater than MaxValue.
示例
下面的示例定义一个实现的类 IConvertible 和一个实现的类 IFormatProvider 。The following example defines a class that implements IConvertible and a class that implements IFormatProvider. 实现的类的对象 IConvertible 保存值的数组 Double 。Objects of the class that implements IConvertible hold an array of Double values. 将每个类的对象传递给 ToDouble 方法。An object of each class is passed to the ToDouble method. 此方法 Double 使用实现的对象 IFormatProvider 来确定如何计算平均值,从而返回值数组的平均值。This method returns an average of the array of Double values, using the object that implements IFormatProvider to determine how to calculate the average.
using namespace System;
using namespace System::Collections;
// Define the types of averaging available in the class
// implementing IConvertible.
public enum class AverageType : short
{
None = 0,
GeometricMean = 1,
ArithmeticMean = 2,
Median = 3
};
// Pass an instance of this class to methods that require an
// IFormatProvider. The class instance determines the type of
// average to calculate.
ref class AverageInfo: public IFormatProvider
{
protected:
AverageType AvgType;
public:
// Specify the type of averaging in the constructor.
AverageInfo( AverageType avgType )
{
this->AvgType = avgType;
}
// This method returns a reference to the containing object
// if an object of AverageInfo type is requested.
virtual Object^ GetFormat( Type^ argType )
{
if ( argType == AverageInfo::typeid)
return this;
else
return (Object^)0;
}
property AverageType TypeOfAverage
{
// Use this property to set or get the type of averaging.
AverageType get()
{
return this->AvgType;
}
void set( AverageType value )
{
this->AvgType = value;
}
}
};
// This class encapsulates an array of double values and implements
// the IConvertible interface. Most of the IConvertible methods
// return an average of the array elements in one of three types:
// arithmetic mean, geometric mean, or median.
ref class DataSet: public IConvertible
{
private:
static Object^ null = nullptr;
protected:
ArrayList^ data;
AverageInfo^ defaultProvider;
// This method unboxes a boxed double.
double UnBoxDouble( Object^ obj )
{
return *static_cast<double^>(obj);
}
public:
// Construct the object and add an initial list of values.
// Create a default format provider.
DataSet( ... array<Double>^values )
{
data = gcnew ArrayList( (Array^)values );
defaultProvider = gcnew AverageInfo( AverageType::ArithmeticMean );
}
// Add additional values with this method.
int Add( double value )
{
data->Add( value );
return data->Count;
}
property double Item[ int ]
{
// Get, set, and add values with this indexer property.
double get( int index )
{
if ( index >= 0 && index < data->Count )
return UnBoxDouble( data[ index ] );
else
throw gcnew InvalidOperationException( "[DataSet.get] Index out of range." );
}
void set( int index, double value )
{
if ( index >= 0 && index < data->Count )
data[ index ] = value;
else
if ( index == data->Count )
data->Add( value );
else
throw gcnew InvalidOperationException( "[DataSet.set] Index out of range." );
}
}
property int Count
{
// This property returns the number of elements in the object.
int get()
{
return data->Count;
}
}
protected:
// This method calculates the average of the object's elements.
double Average( AverageType avgType )
{
double SumProd;
if ( data->Count == 0 )
return 0.0;
switch ( avgType )
{
case AverageType::GeometricMean:
SumProd = 1.0;
for ( int Index = 0; Index < data->Count; Index++ )
SumProd *= UnBoxDouble( data[ Index ] );
// This calculation will not fail with negative
// elements.
return Math::Sign( SumProd ) * Math::Pow( Math::Abs( SumProd ), 1.0 / data->Count );
case AverageType::ArithmeticMean:
SumProd = 0.0;
for ( int Index = 0; Index < data->Count; Index++ )
SumProd += UnBoxDouble( data[ Index ] );
return SumProd / data->Count;
case AverageType::Median:
if ( data->Count % 2 == 0 )
return (UnBoxDouble( data[ data->Count / 2 ] ) + UnBoxDouble( data[ data->Count / 2 - 1 ] )) / 2.0;
else
return UnBoxDouble( data[ data->Count / 2 ] );
default:
return 0.0;
}
}
// Get the AverageInfo object from the caller's format provider,
// or use the local default.
AverageInfo^ GetAverageInfo( IFormatProvider^ provider )
{
AverageInfo^ avgInfo = nullptr;
if ( provider != nullptr )
avgInfo = static_cast<AverageInfo^>(provider->GetFormat( AverageInfo::typeid ));
if ( avgInfo == nullptr )
return defaultProvider;
else
return avgInfo;
}
// Calculate the average and limit the range.
double CalcNLimitAverage( double min, double max, IFormatProvider^ provider )
{
// Get the format provider and calculate the average.
AverageInfo^ avgInfo = GetAverageInfo( provider );
double avg = Average( avgInfo->TypeOfAverage );
// Limit the range, based on the minimum and maximum values
// for the type.
return avg > max ? max : avg < min ? min : avg;
}
public:
// The following elements are required by IConvertible.
// None of these conversion functions throw exceptions. When
// the data is out of range for the type, the appropriate
// MinValue or MaxValue is used.
virtual TypeCode GetTypeCode()
{
return TypeCode::Object;
}
virtual bool ToBoolean( IFormatProvider^ provider )
{
// ToBoolean is false if the dataset is empty.
if ( data->Count <= 0 )
return false;
// For median averaging, ToBoolean is true if any
// non-discarded elements are nonzero.
else
// For median averaging, ToBoolean is true if any
// non-discarded elements are nonzero.
if ( AverageType::Median == GetAverageInfo( provider )->TypeOfAverage )
{
if ( data->Count % 2 == 0 )
return (UnBoxDouble( data[ data->Count / 2 ] ) != 0.0 || UnBoxDouble( data[ data->Count / 2 - 1 ] ) != 0.0);
else
return UnBoxDouble( data[ data->Count / 2 ] ) != 0.0;
}
// For arithmetic or geometric mean averaging, ToBoolean is
// true if any element of the dataset is nonzero.
else
{
for ( int Index = 0; Index < data->Count; Index++ )
if ( UnBoxDouble( data[ Index ] ) != 0.0 )
return true;
return false;
}
}
virtual Byte ToByte( IFormatProvider^ provider )
{
return Convert::ToByte( CalcNLimitAverage( Byte::MinValue, Byte::MaxValue, provider ) );
}
virtual Char ToChar( IFormatProvider^ provider )
{
return Convert::ToChar( Convert::ToUInt16( CalcNLimitAverage( Char::MinValue, Char::MaxValue, provider ) ) );
}
// Convert to DateTime by adding the calculated average as
// seconds to the current date and time. A valid DateTime is
// always returned.
virtual DateTime ToDateTime( IFormatProvider^ provider )
{
double seconds = Average( GetAverageInfo( provider )->TypeOfAverage );
try
{
return DateTime::Now.AddSeconds( seconds );
}
catch ( ArgumentOutOfRangeException^ )
{
return seconds < 0.0 ? DateTime::MinValue : DateTime::MaxValue;
}
}
virtual Decimal ToDecimal( IFormatProvider^ provider )
{
// The Double conversion rounds Decimal.MinValue and
// Decimal.MaxValue to invalid Decimal values, so the
// following limits must be used.
return Convert::ToDecimal( CalcNLimitAverage( -79228162514264330000000000000.0, 79228162514264330000000000000.0, provider ) );
}
virtual double ToDouble( IFormatProvider^ provider )
{
return Average( GetAverageInfo( provider )->TypeOfAverage );
}
virtual short ToInt16( IFormatProvider^ provider )
{
return Convert::ToInt16( CalcNLimitAverage( Int16::MinValue, Int16::MaxValue, provider ) );
}
virtual int ToInt32( IFormatProvider^ provider )
{
return Convert::ToInt32( CalcNLimitAverage( Int32::MinValue, Int32::MaxValue, provider ) );
}
virtual __int64 ToInt64( IFormatProvider^ provider )
{
// The Double conversion rounds Int64.MinValue and
// Int64.MaxValue to invalid Int64 values, so the following
// limits must be used.
return Convert::ToInt64( CalcNLimitAverage( -9223372036854775000, 9223372036854775000, provider ) );
}
virtual signed char ToSByte( IFormatProvider^ provider )
{
return Convert::ToSByte( CalcNLimitAverage( SByte::MinValue, SByte::MaxValue, provider ) );
}
virtual float ToSingle( IFormatProvider^ provider )
{
return Convert::ToSingle( CalcNLimitAverage( Single::MinValue, Single::MaxValue, provider ) );
}
virtual UInt16 ToUInt16( IFormatProvider^ provider )
{
return Convert::ToUInt16( CalcNLimitAverage( UInt16::MinValue, UInt16::MaxValue, provider ) );
}
virtual UInt32 ToUInt32( IFormatProvider^ provider )
{
return Convert::ToUInt32( CalcNLimitAverage( UInt32::MinValue, UInt32::MaxValue, provider ) );
}
virtual UInt64 ToUInt64( IFormatProvider^ provider )
{
// The Double conversion rounds UInt64.MaxValue to an invalid
// UInt64 value, so the following limit must be used.
return Convert::ToUInt64( CalcNLimitAverage( 0, 18446744073709550000.0, provider ) );
}
virtual Object^ ToType( Type^ conversionType, IFormatProvider^ provider )
{
return Convert::ChangeType( Average( GetAverageInfo( provider )->TypeOfAverage ), conversionType );
}
virtual String^ ToString( IFormatProvider^ provider )
{
AverageType avgType = GetAverageInfo( provider )->TypeOfAverage;
return String::Format( "( {0}: {1:G10} )", avgType, Average( avgType ) );
}
};
// Display a DataSet with three different format providers.
void DisplayDataSet( DataSet^ ds )
{
IFormatProvider^ null = nullptr;
String^ fmt = "{0,-12}{1,20}{2,20}{3,20}";
AverageInfo^ median = gcnew AverageInfo( AverageType::Median );
AverageInfo^ geMean = gcnew AverageInfo( AverageType::GeometricMean );
// Display the dataset elements.
if ( ds->Count > 0 )
{
Console::Write( "\nDataSet: [{0}", ds->Item[ 0 ] );
for ( int iX = 1; iX < ds->Count; iX++ )
Console::Write( ", {0}", ds->Item[ iX ] );
Console::WriteLine( "]\n" );
}
Console::WriteLine( fmt, "Convert::", "Default", "Geometric Mean", "Median" );
Console::WriteLine( fmt, "---------", "-------", "--------------", "------" );
Console::WriteLine( fmt, "ToBoolean", Convert::ToBoolean( ds, null ), Convert::ToBoolean( ds, geMean ), Convert::ToBoolean( ds, median ) );
Console::WriteLine( fmt, "ToByte", Convert::ToByte( ds, null ), Convert::ToByte( ds, geMean ), Convert::ToByte( ds, median ) );
Console::WriteLine( fmt, "ToChar", Convert::ToChar( ds, null ), Convert::ToChar( ds, geMean ), Convert::ToChar( ds, median ) );
Console::WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}"
"{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}", "ToDateTime", Convert::ToDateTime( ds, null ), Convert::ToDateTime( ds, geMean ), Convert::ToDateTime( ds, median ) );
Console::WriteLine( fmt, "ToDecimal", Convert::ToDecimal( ds, null ), Convert::ToDecimal( ds, geMean ), Convert::ToDecimal( ds, median ) );
Console::WriteLine( fmt, "ToDouble", Convert::ToDouble( ds, null ), Convert::ToDouble( ds, geMean ), Convert::ToDouble( ds, median ) );
Console::WriteLine( fmt, "ToInt16", Convert::ToInt16( ds, null ), Convert::ToInt16( ds, geMean ), Convert::ToInt16( ds, median ) );
Console::WriteLine( fmt, "ToInt32", Convert::ToInt32( ds, null ), Convert::ToInt32( ds, geMean ), Convert::ToInt32( ds, median ) );
Console::WriteLine( fmt, "ToInt64", Convert::ToInt64( ds, null ), Convert::ToInt64( ds, geMean ), Convert::ToInt64( ds, median ) );
Console::WriteLine( fmt, "ToSByte", Convert::ToSByte( ds, null ), Convert::ToSByte( ds, geMean ), Convert::ToSByte( ds, median ) );
Console::WriteLine( fmt, "ToSingle", Convert::ToSingle( ds, null ), Convert::ToSingle( ds, geMean ), Convert::ToSingle( ds, median ) );
Console::WriteLine( fmt, "ToUInt16", Convert::ToUInt16( ds, null ), Convert::ToUInt16( ds, geMean ), Convert::ToUInt16( ds, median ) );
Console::WriteLine( fmt, "ToUInt32", Convert::ToUInt32( ds, null ), Convert::ToUInt32( ds, geMean ), Convert::ToUInt32( ds, median ) );
Console::WriteLine( fmt, "ToUInt64", Convert::ToUInt64( ds, null ), Convert::ToUInt64( ds, geMean ), Convert::ToUInt64( ds, median ) );
}
int main()
{
Console::WriteLine( "This example of the "
"Convert::To<Type>( Object*, IFormatProvider* ) methods "
"\ngenerates the following output. The example "
"displays the values \nreturned by the methods, "
"using several IFormatProvider objects.\n" );
// To call a [ParamArray] method in C++, you cannot just
// list the parameters, you need to build an array.
array<Double>^dataElem = gcnew array<Double>(6);
dataElem[ 0 ] = 10.5;
dataElem[ 1 ] = 22.2;
dataElem[ 2 ] = 45.9;
dataElem[ 3 ] = 88.7;
dataElem[ 4 ] = 156.05;
dataElem[ 5 ] = 297.6;
DataSet^ ds1 = gcnew DataSet( dataElem );
DisplayDataSet( ds1 );
dataElem = gcnew array<Double>(5);
dataElem[ 0 ] = 359999.95;
dataElem[ 1 ] = 425000;
dataElem[ 2 ] = 499999.5;
dataElem[ 3 ] = 775000;
dataElem[ 4 ] = 1695000;
DataSet^ ds2 = gcnew DataSet( dataElem );
DisplayDataSet( ds2 );
}
/*
This example of the Convert::To<Type>( Object*, IFormatProvider* ) methods
generates the following output. The example displays the values
returned by the methods, using several IFormatProvider objects.
DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
Convert:: Default Geometric Mean Median
--------- ------- -------------- ------
ToBoolean True True True
ToByte 103 59 67
ToChar g ; C
ToDateTime 2003-05-13 15:30:23 2003-05-13 15:29:39 2003-05-13 15:29:47
ToDecimal 103.491666666667 59.4332135445164 67.3
ToDouble 103.491666666667 59.4332135445164 67.3
ToInt16 103 59 67
ToInt32 103 59 67
ToInt64 103 59 67
ToSByte 103 59 67
ToSingle 103.4917 59.43321 67.3
ToUInt16 103 59 67
ToUInt32 103 59 67
ToUInt64 103 59 67
DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
Convert:: Default Geometric Mean Median
--------- ------- -------------- ------
ToBoolean True True True
ToByte 255 255 255
ToChar ? ? ?
ToDateTime 2003-05-22 08:05:19 2003-05-20 22:54:57 2003-05-19 10:21:59
ToDecimal 750999.89 631577.237188435 499999.5
ToDouble 750999.89 631577.237188435 499999.5
ToInt16 32767 32767 32767
ToInt32 751000 631577 500000
ToInt64 751000 631577 500000
ToSByte 127 127 127
ToSingle 750999.9 631577.3 499999.5
ToUInt16 65535 65535 65535
ToUInt32 751000 631577 500000
ToUInt64 751000 631577 500000
*/
using System;
using System.Collections;
// Define the types of averaging available in the class
// implementing IConvertible.
public enum AverageType : short
{
None = 0,
GeometricMean = 1,
ArithmeticMean = 2,
Median = 3
};
// Pass an instance of this class to methods that require an
// IFormatProvider. The class instance determines the type of
// average to calculate.
public class AverageInfo : IFormatProvider
{
protected AverageType AvgType;
// Specify the type of averaging in the constructor.
public AverageInfo( AverageType avgType )
{
this.AvgType = avgType;
}
// This method returns a reference to the containing object
// if an object of AverageInfo type is requested.
public object GetFormat( Type argType )
{
if ( argType == typeof( AverageInfo ) )
return this;
else
return null;
}
// Use this property to set or get the type of averaging.
public AverageType TypeOfAverage
{
get { return this.AvgType; }
set { this.AvgType = value; }
}
}
// This class encapsulates an array of double values and implements
// the IConvertible interface. Most of the IConvertible methods
// return an average of the array elements in one of three types:
// arithmetic mean, geometric mean, or median.
public class DataSet : IConvertible
{
protected ArrayList data;
protected AverageInfo defaultProvider;
// Construct the object and add an initial list of values.
// Create a default format provider.
public DataSet( params double[ ] values )
{
data = new ArrayList( values );
defaultProvider =
new AverageInfo( AverageType.ArithmeticMean );
}
// Add additional values with this method.
public int Add( double value )
{
data.Add( value );
return data.Count;
}
// Get, set, and add values with this indexer property.
public double this[ int index ]
{
get
{
if( index >= 0 && index < data.Count )
return (double)data[ index ];
else
throw new InvalidOperationException(
"[DataSet.get] Index out of range." );
}
set
{
if( index >= 0 && index < data.Count )
data[ index ] = value;
else if( index == data.Count )
data.Add( value );
else
throw new InvalidOperationException(
"[DataSet.set] Index out of range." );
}
}
// This property returns the number of elements in the object.
public int Count
{
get { return data.Count; }
}
// This method calculates the average of the object's elements.
protected double Average( AverageType avgType )
{
double SumProd;
if( data.Count == 0 )
return 0.0;
switch( avgType )
{
case AverageType.GeometricMean:
SumProd = 1.0;
for( int Index = 0; Index < data.Count; Index++ )
SumProd *= (double)data[ Index ];
// This calculation will not fail with negative
// elements.
return Math.Sign( SumProd ) * Math.Pow(
Math.Abs( SumProd ), 1.0 / data.Count );
case AverageType.ArithmeticMean:
SumProd = 0.0;
for( int Index = 0; Index < data.Count; Index++ )
SumProd += (double)data[ Index ];
return SumProd / data.Count;
case AverageType.Median:
if( data.Count % 2 == 0 )
return ( (double)data[ data.Count / 2 ] +
(double)data[ data.Count / 2 - 1 ] ) / 2.0;
else
return (double)data[ data.Count / 2 ];
default:
return 0.0;
}
}
// Get the AverageInfo object from the caller's format provider,
// or use the local default.
protected AverageInfo GetAverageInfo( IFormatProvider provider )
{
AverageInfo avgInfo = null;
if( provider != null )
avgInfo = (AverageInfo)provider.GetFormat(
typeof( AverageInfo ) );
if ( avgInfo == null )
return defaultProvider;
else
return avgInfo;
}
// Calculate the average and limit the range.
protected double CalcNLimitAverage( double min, double max,
IFormatProvider provider )
{
// Get the format provider and calculate the average.
AverageInfo avgInfo = GetAverageInfo( provider );
double avg = Average( avgInfo.TypeOfAverage );
// Limit the range, based on the minimum and maximum values
// for the type.
return avg > max ? max : avg < min ? min : avg;
}
// The following elements are required by IConvertible.
// None of these conversion functions throw exceptions. When
// the data is out of range for the type, the appropriate
// MinValue or MaxValue is used.
public TypeCode GetTypeCode( )
{
return TypeCode.Object;
}
public bool ToBoolean( IFormatProvider provider )
{
// ToBoolean is false if the dataset is empty.
if( data.Count <= 0 )
{
return false;
}
// For median averaging, ToBoolean is true if any
// non-discarded elements are nonzero.
else if( AverageType.Median ==
GetAverageInfo( provider ).TypeOfAverage )
{
if (data.Count % 2 == 0 )
return ( (double)data[ data.Count / 2 ] != 0.0 ||
(double)data[ data.Count / 2 - 1 ] != 0.0 );
else
return (double)data[ data.Count / 2 ] != 0.0;
}
// For arithmetic or geometric mean averaging, ToBoolean is
// true if any element of the dataset is nonzero.
else
{
for( int Index = 0; Index < data.Count; Index++ )
if( (double)data[ Index ] != 0.0 )
return true;
return false;
}
}
public byte ToByte( IFormatProvider provider )
{
return Convert.ToByte( CalcNLimitAverage(
Byte.MinValue, Byte.MaxValue, provider ) );
}
public char ToChar( IFormatProvider provider )
{
return Convert.ToChar( Convert.ToUInt16( CalcNLimitAverage(
Char.MinValue, Char.MaxValue, provider ) ) );
}
// Convert to DateTime by adding the calculated average as
// seconds to the current date and time. A valid DateTime is
// always returned.
public DateTime ToDateTime( IFormatProvider provider )
{
double seconds =
Average( GetAverageInfo( provider ).TypeOfAverage );
try
{
return DateTime.Now.AddSeconds( seconds );
}
catch( ArgumentOutOfRangeException )
{
return seconds < 0.0 ? DateTime.MinValue : DateTime.MaxValue;
}
}
public decimal ToDecimal( IFormatProvider provider )
{
// The Double conversion rounds Decimal.MinValue and
// Decimal.MaxValue to invalid Decimal values, so the
// following limits must be used.
return Convert.ToDecimal( CalcNLimitAverage(
-79228162514264330000000000000.0,
79228162514264330000000000000.0, provider ) );
}
public double ToDouble( IFormatProvider provider )
{
return Average( GetAverageInfo(provider).TypeOfAverage );
}
public short ToInt16( IFormatProvider provider )
{
return Convert.ToInt16( CalcNLimitAverage(
Int16.MinValue, Int16.MaxValue, provider ) );
}
public int ToInt32( IFormatProvider provider )
{
return Convert.ToInt32( CalcNLimitAverage(
Int32.MinValue, Int32.MaxValue, provider ) );
}
public long ToInt64( IFormatProvider provider )
{
// The Double conversion rounds Int64.MinValue and
// Int64.MaxValue to invalid Int64 values, so the following
// limits must be used.
return Convert.ToInt64( CalcNLimitAverage(
-9223372036854775000, 9223372036854775000, provider ) );
}
public SByte ToSByte( IFormatProvider provider )
{
return Convert.ToSByte( CalcNLimitAverage(
SByte.MinValue, SByte.MaxValue, provider ) );
}
public float ToSingle( IFormatProvider provider )
{
return Convert.ToSingle( CalcNLimitAverage(
Single.MinValue, Single.MaxValue, provider ) );
}
public UInt16 ToUInt16( IFormatProvider provider )
{
return Convert.ToUInt16( CalcNLimitAverage(
UInt16.MinValue, UInt16.MaxValue, provider ) );
}
public UInt32 ToUInt32( IFormatProvider provider )
{
return Convert.ToUInt32( CalcNLimitAverage(
UInt32.MinValue, UInt32.MaxValue, provider ) );
}
public UInt64 ToUInt64( IFormatProvider provider )
{
// The Double conversion rounds UInt64.MaxValue to an invalid
// UInt64 value, so the following limit must be used.
return Convert.ToUInt64( CalcNLimitAverage(
0, 18446744073709550000.0, provider ) );
}
public object ToType( Type conversionType,
IFormatProvider provider )
{
return Convert.ChangeType( Average(
GetAverageInfo( provider ).TypeOfAverage ),
conversionType );
}
public string ToString( IFormatProvider provider )
{
AverageType avgType = GetAverageInfo( provider ).TypeOfAverage;
return String.Format( "( {0}: {1:G10} )", avgType,
Average( avgType ) );
}
}
class IConvertibleProviderDemo
{
// Display a DataSet with three different format providers.
public static void DisplayDataSet( DataSet ds )
{
string fmt = "{0,-12}{1,20}{2,20}{3,20}";
AverageInfo median = new AverageInfo( AverageType.Median );
AverageInfo geMean =
new AverageInfo( AverageType.GeometricMean );
// Display the dataset elements.
if( ds.Count > 0 )
{
Console.Write( "\nDataSet: [{0}", ds[ 0 ] );
for( int iX = 1; iX < ds.Count; iX++ )
Console.Write( ", {0}", ds[ iX ] );
Console.WriteLine( "]\n" );
}
Console.WriteLine( fmt, "Convert.", "Default",
"Geometric Mean", "Median");
Console.WriteLine( fmt, "--------", "-------",
"--------------", "------");
Console.WriteLine( fmt, "ToBoolean",
Convert.ToBoolean( ds, null ),
Convert.ToBoolean( ds, geMean ),
Convert.ToBoolean( ds, median ) );
Console.WriteLine( fmt, "ToByte",
Convert.ToByte( ds, null ),
Convert.ToByte( ds, geMean ),
Convert.ToByte( ds, median ) );
Console.WriteLine( fmt, "ToChar",
Convert.ToChar( ds, null ),
Convert.ToChar( ds, geMean ),
Convert.ToChar( ds, median ) );
Console.WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}" +
"{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}",
"ToDateTime", Convert.ToDateTime( ds, null ),
Convert.ToDateTime( ds, geMean ),
Convert.ToDateTime( ds, median ) );
Console.WriteLine( fmt, "ToDecimal",
Convert.ToDecimal( ds, null ),
Convert.ToDecimal( ds, geMean ),
Convert.ToDecimal( ds, median ) );
Console.WriteLine( fmt, "ToDouble",
Convert.ToDouble( ds, null ),
Convert.ToDouble( ds, geMean ),
Convert.ToDouble( ds, median ) );
Console.WriteLine( fmt, "ToInt16",
Convert.ToInt16( ds, null ),
Convert.ToInt16( ds, geMean ),
Convert.ToInt16( ds, median ) );
Console.WriteLine( fmt, "ToInt32",
Convert.ToInt32( ds, null ),
Convert.ToInt32( ds, geMean ),
Convert.ToInt32( ds, median ) );
Console.WriteLine( fmt, "ToInt64",
Convert.ToInt64( ds, null ),
Convert.ToInt64( ds, geMean ),
Convert.ToInt64( ds, median ) );
Console.WriteLine( fmt, "ToSByte",
Convert.ToSByte( ds, null ),
Convert.ToSByte( ds, geMean ),
Convert.ToSByte( ds, median ) );
Console.WriteLine( fmt, "ToSingle",
Convert.ToSingle( ds, null ),
Convert.ToSingle( ds, geMean ),
Convert.ToSingle( ds, median ) );
Console.WriteLine( fmt, "ToUInt16",
Convert.ToUInt16( ds, null ),
Convert.ToUInt16( ds, geMean ),
Convert.ToUInt16( ds, median ) );
Console.WriteLine( fmt, "ToUInt32",
Convert.ToUInt32( ds, null ),
Convert.ToUInt32( ds, geMean ),
Convert.ToUInt32( ds, median ) );
Console.WriteLine( fmt, "ToUInt64",
Convert.ToUInt64( ds, null ),
Convert.ToUInt64( ds, geMean ),
Convert.ToUInt64( ds, median ) );
}
public static void Main( )
{
Console.WriteLine( "This example of " +
"the Convert.To<Type>( object, IFormatProvider ) methods " +
"\ngenerates the following output. The example " +
"displays the values \nreturned by the methods, " +
"using several IFormatProvider objects.\n" );
DataSet ds1 = new DataSet(
10.5, 22.2, 45.9, 88.7, 156.05, 297.6 );
DisplayDataSet( ds1 );
DataSet ds2 = new DataSet(
359999.95, 425000, 499999.5, 775000, 1695000 );
DisplayDataSet( ds2 );
}
}
/*
This example of the Convert.To<Type>( object, IFormatProvider ) methods
generates the following output. The example displays the values
returned by the methods, using several IFormatProvider objects.
DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
Convert. Default Geometric Mean Median
-------- ------- -------------- ------
ToBoolean True True True
ToByte 103 59 67
ToChar g ; C
ToDateTime 2003-05-13 15:04:12 2003-05-13 15:03:28 2003-05-13 15:03:35
ToDecimal 103.491666666667 59.4332135445164 67.3
ToDouble 103.491666666667 59.4332135445164 67.3
ToInt16 103 59 67
ToInt32 103 59 67
ToInt64 103 59 67
ToSByte 103 59 67
ToSingle 103.4917 59.43321 67.3
ToUInt16 103 59 67
ToUInt32 103 59 67
ToUInt64 103 59 67
DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
Convert. Default Geometric Mean Median
-------- ------- -------------- ------
ToBoolean True True True
ToByte 255 255 255
ToChar ? ? ?
ToDateTime 2003-05-22 07:39:08 2003-05-20 22:28:45 2003-05-19 09:55:48
ToDecimal 750999.89 631577.237188435 499999.5
ToDouble 750999.89 631577.237188435 499999.5
ToInt16 32767 32767 32767
ToInt32 751000 631577 500000
ToInt64 751000 631577 500000
ToSByte 127 127 127
ToSingle 750999.9 631577.3 499999.5
ToUInt16 65535 65535 65535
ToUInt32 751000 631577 500000
ToUInt64 751000 631577 500000
*/
Imports System.Collections
Module IConvertibleProviderDemo
' Define the types of averaging available in the class
' implementing IConvertible.
Enum AverageType as Short
None = 0
GeometricMean = 1
ArithmeticMean = 2
Median = 3
End Enum
' Pass an instance of this class to methods that require an
' IFormatProvider. The class instance determines the type of
' average to calculate.
Public Class AverageInfo
Implements IFormatProvider
Protected AvgType As AverageType
' Specify the type of averaging in the constructor.
Public Sub New( avgType As AverageType )
Me.AvgType = avgType
End Sub
' This method returns a reference to the containing object
' if an object of AverageInfo type is requested.
Public Function GetFormat( argType As Type ) As Object _
Implements IFormatProvider.GetFormat
If argType Is GetType( AverageInfo ) Then
Return Me
Else
Return Nothing
End If
End Function
' Use this property to set or get the type of averaging.
Public Property TypeOfAverage( ) As AverageType
Get
Return Me.AvgType
End Get
Set( ByVal value as AverageType )
Me.AvgType = value
End Set
End Property
End Class
' This class encapsulates an array of Double values and implements
' the IConvertible interface. Most of the IConvertible methods
' return an average of the array elements in one of three types:
' arithmetic mean, geometric mean, or median.
Public Class DataSet
Implements IConvertible
Protected data As ArrayList
Protected defaultProvider As AverageInfo
' Construct the object and add an initial list of values.
' Create a default format provider.
Public Sub New( ParamArray values( ) As Double )
data = New ArrayList( values )
defaultProvider = New AverageInfo( _
AverageType.ArithmeticMean )
End Sub
' Add additional values with this method.
Public Function Add( value As Double ) As Integer
data.Add( value )
Return data.Count
End Function
' Get, set, and add values with this indexer property.
Default Public Property Item(index As Integer) As Double
Get
If index >= 0 AndAlso index < data.Count Then
Return System.Convert.ToDouble( data( index ) )
Else
Throw New InvalidOperationException( _
"[DataSet.get] Index out of range." )
End If
End Get
Set
If index >= 0 AndAlso index < data.Count Then
data( index ) = value
ElseIf index = data.Count Then
data.Add( value )
Else
Throw New InvalidOperationException( _
"[DataSet.set] Index out of range." )
End If
End Set
End Property
' This property returns the number of elements in the object.
Public ReadOnly Property Count( ) As Integer
Get
Return data.Count
End Get
End Property
' This method calculates the average of the object's elements.
Protected Function Average( ByVal avgType As AverageType ) As Double
Dim SumProd As Double
Dim Index As Integer
If data.Count = 0 Then Return 0.0
Select Case avgType
Case AverageType.GeometricMean
SumProd = 1.0
For Index = 0 To data.Count - 1
SumProd *= data( Index )
Next Index
' This calculation will not fail with negative
' elements.
Return Math.Sign( SumProd ) * Math.Pow( _
Math.Abs( SumProd ), 1.0 / data.Count )
Case AverageType.ArithmeticMean
SumProd = 0.0
For Index = 0 To data.Count - 1
SumProd += data( Index )
Next Index
Return SumProd / data.Count
Case AverageType.Median
If data.Count Mod 2 = 0 Then
Return ( data( data.Count \ 2 ) + _
data( data.Count \ 2 - 1 ) ) / 2.0
Else
Return data( data.Count \ 2 )
End If
End Select
End Function
' Get the AverageInfo object from the caller's format
' provider, or use the local default.
Protected Function GetAverageInfo( _
provider As IFormatProvider ) As AverageInfo
Dim avgInfo As AverageInfo = Nothing
If Not provider Is Nothing Then
avgInfo = provider.GetFormat( GetType( AverageInfo ) )
End If
Return IIf( avgInfo Is Nothing, defaultProvider, avgInfo )
End Function
' Calculate the average and limit the range.
Protected Function CalcNLimitAverage( min As Double, _
max As Double, provider as IFormatProvider ) As Double
' Get the format provider and calculate the average.
Dim avgInfo As AverageInfo = GetAverageInfo( provider )
Dim avg As Double = Average( avgInfo.TypeOfAverage )
' Limit the range, based on the minimum and maximum values
' for the type.
Return IIf( avg > max, max, IIf( avg < min, min, avg ) )
End Function
' The following elements are required by IConvertible.
' None of these conversion functions throw exceptions. When
' the data is out of range for the type, the appropriate
' MinValue or MaxValue is used.
Public Function GetTypeCode( ) As TypeCode _
Implements IConvertible.GetTypeCode
Return TypeCode.Object
End Function
Function ToBoolean( ByVal provider As IFormatProvider ) As _
Boolean Implements IConvertible.ToBoolean
' ToBoolean is false if the dataset is empty.
If data.Count <= 0 Then
Return False
' For median averaging, ToBoolean is true if any
' non-discarded elements are nonzero.
ElseIf AverageType.Median = _
GetAverageInfo( provider ).TypeOfAverage Then
If data.Count Mod 2 = 0 Then
Return ( data( data.Count \ 2 ) <> 0.0 Or _
data( data.Count \ 2 - 1 ) <> 0.0 )
Else
Return data( data.Count \ 2 ) <> 0.0
End If
' For arithmetic or geometric mean averaging, ToBoolean is
' true if any element of the dataset is nonzero.
Else
Dim Index As Integer
For Index = 0 To data.Count - 1
If data( Index ) <> 0.0 Then Return True
Next Index
Return False
End If
End Function
Function ToByte( ByVal provider As IFormatProvider ) As Byte _
Implements IConvertible.ToByte
Return Convert.ToByte( CalcNLimitAverage( _
Byte.MinValue, Byte.MaxValue, provider ) )
End Function
Function ToChar( ByVal provider As IFormatProvider ) As Char _
Implements IConvertible.ToChar
Return Convert.ToChar( Convert.ToUInt16( _
CalcNLimitAverage( 0.0, &HFFFF, provider ) ) )
End Function
' Convert to DateTime by adding the calculated average as
' seconds to the current date and time. A valid DateTime is
' always returned.
Function ToDateTime( ByVal provider As IFormatProvider ) As _
DateTime Implements IConvertible.ToDateTime
Dim seconds As Double = Average( _
GetAverageInfo( provider ).TypeOfAverage )
Try
Return DateTime.Now.AddSeconds( seconds )
Catch ex As ArgumentOutOfRangeException
Return IIf( seconds < 0.0, DateTime.MinValue, _
DateTime.MaxValue )
End Try
End Function
Function ToDecimal( ByVal provider As IFormatProvider ) As _
Decimal Implements IConvertible.ToDecimal
' The Double conversion rounds Decimal.MinValue and
' Decimal.MaxValue to invalid Decimal values, so the
' following limits must be used.
Return Convert.ToDecimal( CalcNLimitAverage( _
-79228162514264330000000000000.0, _
79228162514264330000000000000.0, provider ) )
End Function
Function ToDouble( ByVal provider As IFormatProvider) As _
Double Implements IConvertible.ToDouble
Return Average( GetAverageInfo( provider ).TypeOfAverage )
End Function
Function ToInt16( ByVal provider As IFormatProvider ) As _
Short Implements IConvertible.ToInt16
Return Convert.ToInt16( CalcNLimitAverage( _
Int16.MinValue, Int16.MaxValue, provider ) )
End Function
Function ToInt32( ByVal provider As IFormatProvider ) As _
Integer Implements IConvertible.ToInt32
Return Convert.ToInt32( CalcNLimitAverage( _
Int32.MinValue, Int32.MaxValue, provider ) )
End Function
Function ToInt64( ByVal provider As IFormatProvider ) As Long _
Implements IConvertible.ToInt64
' The Double conversion rounds Int64.MinValue and
' Int64.MaxValue to invalid Long values, so the following
' limits must be used.
Return Convert.ToInt64( CalcNLimitAverage( _
-9223372036854775000, 9223372036854775000, provider ) )
End Function
Function ToSByte( ByVal provider As IFormatProvider ) As _
SByte Implements IConvertible.ToSByte
' SByte.MinValue and SByte.MaxValue are not defined in
' Visual Basic.
Return Convert.ToSByte( CalcNLimitAverage( _
-128, 127, provider ) )
End Function
Function ToSingle( ByVal provider As IFormatProvider ) As _
Single Implements IConvertible.ToSingle
Return Convert.ToSingle( CalcNLimitAverage( _
Single.MinValue, Single.MaxValue, provider ) )
End Function
Function ToUInt16( ByVal provider As IFormatProvider ) As _
UInt16 Implements IConvertible.ToUInt16
' UInt16.MinValue and UInt16.MaxValue are not defined in
' Visual Basic.
Return Convert.ToUInt16( CalcNLimitAverage( _
0, &HFFFF, provider ) )
End Function
Function ToUInt32( ByVal provider As IFormatProvider ) As _
UInt32 Implements IConvertible.ToUInt32
' UInt32.MinValue and UInt32.MaxValue are not defined in
' Visual Basic.
Return Convert.ToUInt32( CalcNLimitAverage( _
0, 4294967295, provider ) )
End Function
Function ToUInt64( ByVal provider As IFormatProvider ) As _
UInt64 Implements IConvertible.ToUInt64
' UInt64.MinValue and UInt64.MaxValue are not defined in
' Visual Basic. The Double conversion would have rounded
' UInt64.MaxValue, so the following limit must be used.
Return Convert.ToUInt64( CalcNLimitAverage( _
0, 18446744073709550000.0, provider ) )
End Function
Function ToType( ByVal conversionType As Type, _
ByVal provider As IFormatProvider) As Object _
Implements IConvertible.ToType
Return Convert.ChangeType( Average( GetAverageInfo( _
provider ).TypeOfAverage ), conversionType )
End Function
Overloads Function ToString( ByVal provider As IFormatProvider _
) As String Implements IConvertible.ToString
Dim avgType as AverageType = _
GetAverageInfo( provider ).TypeOfAverage
Return String.Format( "( {0}: {1:G10} )", avgType, _
Average( avgType ) )
End Function
End Class
' Display a DataSet with three different format providers.
Sub DisplayDataSet( ds As DataSet )
Dim fmt As String = "{0,-12}{1,20}{2,20}{3,20}"
Dim median As AverageInfo = New AverageInfo( AverageType.Median )
Dim geMean As AverageInfo = _
New AverageInfo( AverageType.GeometricMean )
Dim iX As Integer
' Display the dataset elements.
If ds.Count > 0 Then
Console.Write( vbCrLf & "DataSet: [{0}", ds( 0 ) )
For iX = 1 To ds.Count - 1
Console.Write( ", {0}", ds( iX ) )
Next iX
Console.WriteLine( "]" & vbCrLf )
End If
Console.WriteLine( fmt, "Convert.", "Default", _
"Geometric Mean", "Median" )
Console.WriteLine( fmt, "--------", "-------", _
"--------------", "------" )
Console.WriteLine( fmt, "ToBoolean", _
Convert.ToBoolean( ds, Nothing ), _
Convert.ToBoolean( ds, geMean ), _
Convert.ToBoolean( ds, median ) )
Console.WriteLine( fmt, "ToByte", _
Convert.ToByte( ds, Nothing ), _
Convert.ToByte( ds, geMean ), _
Convert.ToByte( ds, median ) )
Console.WriteLine( fmt, "ToChar", _
Convert.ToChar( ds, Nothing ), _
Convert.ToChar( ds, geMean ), _
Convert.ToChar( ds, median ) )
Console.WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}" & _
"{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}", _
"ToDateTime", Convert.ToDateTime( ds, Nothing ), _
Convert.ToDateTime( ds, geMean ), _
Convert.ToDateTime( ds, median ) )
Console.WriteLine( fmt, "ToDecimal", _
Convert.ToDecimal( ds, Nothing ), _
Convert.ToDecimal( ds, geMean ), _
Convert.ToDecimal( ds, median ) )
Console.WriteLine( fmt, "ToDouble", _
Convert.ToDouble( ds, Nothing ), _
Convert.ToDouble( ds, geMean ), _
Convert.ToDouble( ds, median ) )
Console.WriteLine( fmt, "ToInt16", _
Convert.ToInt16( ds, Nothing ), _
Convert.ToInt16( ds, geMean ), _
Convert.ToInt16( ds, median ) )
Console.WriteLine( fmt, "ToInt32", _
Convert.ToInt32( ds, Nothing ), _
Convert.ToInt32( ds, geMean ), _
Convert.ToInt32( ds, median ) )
Console.WriteLine( fmt, "ToInt64", _
Convert.ToInt64( ds, Nothing ), _
Convert.ToInt64( ds, geMean ), _
Convert.ToInt64( ds, median ) )
Console.WriteLine( fmt, "ToSByte", _
Convert.ToSByte( ds, Nothing ), _
Convert.ToSByte( ds, geMean ), _
Convert.ToSByte( ds, median ) )
Console.WriteLine( fmt, "ToSingle", _
Convert.ToSingle( ds, Nothing ), _
Convert.ToSingle( ds, geMean ), _
Convert.ToSingle( ds, median ) )
Console.WriteLine( fmt, "ToUInt16", _
Convert.ToUInt16( ds, Nothing ), _
Convert.ToUInt16( ds, geMean ), _
Convert.ToUInt16( ds, median ) )
Console.WriteLine( fmt, "ToUInt32", _
Convert.ToUInt32( ds, Nothing ), _
Convert.ToUInt32( ds, geMean ), _
Convert.ToUInt32( ds, median ) )
Console.WriteLine( fmt, "ToUInt64", _
Convert.ToUInt64( ds, Nothing ), _
Convert.ToUInt64( ds, geMean ), _
Convert.ToUInt64( ds, median ) )
End Sub
Sub Main( )
Console.WriteLine( _
"This example of the Convert.To<Type>( Object, " & _
"IFormatProvider ) methods " & vbCrLf & "generates " & _
"the following output. The example displays the " & _
"values " & vbCrLf & "returned by the methods, " & _
"using several IFormatProvider objects." & vbCrLf )
Dim ds1 As New DataSet( 10.5, 22.2, 45.9, 88.7, 156.05, 297.6 )
DisplayDataSet( ds1 )
Dim ds2 As New DataSet( _
359999.95, 425000, 499999.5, 775000, 1695000 )
DisplayDataSet( ds2 )
End Sub
End Module
' This example of the Convert.To<Type>( Object, IFormatProvider ) methods
' generates the following output. The example displays the values
' returned by the methods, using several IFormatProvider objects.
'
' DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
'
' Convert. Default Geometric Mean Median
' -------- ------- -------------- ------
' ToBoolean True True True
' ToByte 103 59 67
' ToChar g ; C
' ToDateTime 2003-05-13 14:52:53 2003-05-13 14:52:09 2003-05-13 14:52:17
' ToDecimal 103.491666666667 59.4332135445164 67.3
' ToDouble 103.491666666667 59.4332135445164 67.3
' ToInt16 103 59 67
' ToInt32 103 59 67
' ToInt64 103 59 67
' ToSByte 103 59 67
' ToSingle 103.4917 59.43321 67.3
' ToUInt16 103 59 67
' ToUInt32 103 59 67
' ToUInt64 103 59 67
'
' DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
'
' Convert. Default Geometric Mean Median
' -------- ------- -------------- ------
' ToBoolean True True True
' ToByte 255 255 255
' ToChar ? ? ?
' ToDateTime 2003-05-22 07:27:49 2003-05-20 22:17:27 2003-05-19 09:44:29
' ToDecimal 750999.89 631577.237188435 499999.5
' ToDouble 750999.89 631577.237188435 499999.5
' ToInt16 32767 32767 32767
' ToInt32 751000 631577 500000
' ToInt64 751000 631577 500000
' ToSByte 127 127 127
' ToSingle 750999.9 631577.3 499999.5
' ToUInt16 65535 65535 65535
' ToUInt32 751000 631577 500000
' ToUInt64 751000 631577 500000
注解
返回值是调用的 IConvertible.ToDouble 基础类型的方法的结果 value 。The return value is the result of invoking the IConvertible.ToDouble method of the underlying type of value.
provider 使用户能够指定有关的内容的特定于区域性的转换信息 value 。provider enables the user to specify culture-specific conversion information about the contents of value. 例如,如果 value 是表示数字的,则 String provider 可能提供有关用于表示该数字的表示法的区域性特定信息。For example, if value is a String that represents a number, provider could supply culture-specific information about the notation used to represent that number.
基类型将忽略 provider ; 但是,如果 value 是实现接口的用户定义类型,则可以使用参数 IConvertible 。The base types ignore provider; however, the parameter may be used if value is a user-defined type that implements the IConvertible interface.
适用于
ToDouble(UInt64)
重要
此 API 不符合 CLS。
将指定的 64 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 64-bit unsigned integer to an equivalent double-precision floating-point number.
public:
static double ToDouble(System::UInt64 value);
[System.CLSCompliant(false)]
public static double ToDouble (ulong value);
[<System.CLSCompliant(false)>]
static member ToDouble : uint64 -> double
Public Shared Function ToDouble (value As ULong) As Double
参数
- value
- UInt64
要转换的 64 位无符号整数。The 64-bit unsigned integer to convert.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
- 属性
示例
下面的示例将值数组中的每个元素转换 UInt64 为一个 Double 值。The following example converts each element in an array of UInt64 values to a Double value.
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.
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.
适用于
ToDouble(UInt32)
重要
此 API 不符合 CLS。
将指定的 32 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 32-bit unsigned integer to an equivalent double-precision floating-point number.
public:
static double ToDouble(System::UInt32 value);
[System.CLSCompliant(false)]
public static double ToDouble (uint value);
[<System.CLSCompliant(false)>]
static member ToDouble : uint32 -> double
Public Shared Function ToDouble (value As UInteger) As Double
参数
- value
- UInt32
要转换的 32 位无符号整数。The 32-bit unsigned integer to convert.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
- 属性
示例
下面的示例将值数组中的每个元素转换 UInt32 为一个 Double 值。The following example converts each element in an array of UInt32 values to a Double value.
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.
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.
适用于
ToDouble(UInt16)
重要
此 API 不符合 CLS。
将指定的 16 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 16-bit unsigned integer to the equivalent double-precision floating-point number.
public:
static double ToDouble(System::UInt16 value);
[System.CLSCompliant(false)]
public static double ToDouble (ushort value);
[<System.CLSCompliant(false)>]
static member ToDouble : uint16 -> double
Public Shared Function ToDouble (value As UShort) As Double
参数
- value
- UInt16
要转换的 16 位无符号整数。The 16-bit unsigned integer to convert.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
- 属性
示例
下面的示例将值数组中的每个元素转换 UInt16 为一个 Double 值。The following example converts each element in an array of UInt16 values to a Double value.
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.
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.
适用于
ToDouble(String)
将数字的指定字符串表示形式转换为等效的双精度浮点数。Converts the specified string representation of a number to an equivalent double-precision floating-point number.
public:
static double ToDouble(System::String ^ value);
public static double ToDouble (string value);
public static double ToDouble (string? value);
static member ToDouble : string -> double
Public Shared Function ToDouble (value As String) As Double
参数
- value
- String
包含要转换的数字的字符串。A string that contains the number to convert.
返回
与 value 中数字等效的双精度浮点数,如果 value 为 null,则为 0(零)。A double-precision floating-point number that is equivalent to the number in value, or 0 (zero) if value is null.
例外
value 不是一个具有有效格式的数字。value is not a number in a valid format.
value 表示一个小于 MinValue 或大于 MaxValue 的数字。value represents a number that is less than MinValue or greater than MaxValue.
示例
下面的示例尝试将数值字符串数组中的每个元素转换为 Double 。The following example attempts to convert each element in an array of numeric strings to a Double. 该示例的输出来自当前区域性为 en-us 的系统。The example's output is from a system whose current culture is 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.
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.
注解
使用 ToDouble(String) 方法等效于传递 value 到 Double.Parse(String) 方法。Using the ToDouble(String) method is equivalent to passing value to the Double.Parse(String) method. 使用当前线程区域性的格式设置约定解释 value。value is interpreted by using the formatting conventions of the current thread culture.
如果你不希望在转换失败时处理异常,则可以改为调用 Double.TryParse 方法。If you prefer not to handle an exception if the conversion fails, you can call the Double.TryParse method instead. 它将返回一个 Boolean 值,该值指示转换是成功还是失败。It returns a Boolean value that indicates whether the conversion succeeded or failed.
适用于
ToDouble(String, IFormatProvider)
使用指定的区域性特定格式设置信息,将数字的指定字符串表示形式转换为等效的双精度浮点数。Converts the specified string representation of a number to an equivalent double-precision floating-point number, using the specified culture-specific formatting information.
public:
static double ToDouble(System::String ^ value, IFormatProvider ^ provider);
public static double ToDouble (string value, IFormatProvider provider);
public static double ToDouble (string? value, IFormatProvider? provider);
static member ToDouble : string * IFormatProvider -> double
Public Shared Function ToDouble (value As String, provider As IFormatProvider) As Double
参数
- value
- String
包含要转换的数字的字符串。A string that contains the number to convert.
- provider
- IFormatProvider
一个提供区域性特定的格式设置信息的对象。An object that supplies culture-specific formatting information.
返回
与 value 中数字等效的双精度浮点数,如果 value 为 null,则为 0(零)。A double-precision floating-point number that is equivalent to the number in value, or 0 (zero) if value is null.
例外
value 不是一个具有有效格式的数字。value is not a number in a valid format.
value 表示一个小于 MinValue 或大于 MaxValue 的数字。value represents a number that is less than MinValue or greater than MaxValue.
示例
下面的示例使用对象通过方法转换值的字符串表示形式 Double ToDouble IFormatProvider 。The following example converts string representations of Double values with the ToDouble method, using an IFormatProvider object.
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
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
注解
返回值是对调用方法的结果 Double.Parse value 。The return value is the result of invoking the Double.Parse method on value.
provider 是一个 IFormatProvider 获取对象的实例 NumberFormatInfo 。provider is an IFormatProvider instance that obtains a NumberFormatInfo object. NumberFormatInfo对象提供有关的格式的区域性特定信息 value 。The NumberFormatInfo object provides culture-specific information about the format of value. 如果 provider 为 null ,则 NumberFormatInfo 使用当前区域性的。If provider is null, the NumberFormatInfo for the current culture is used.
如果你不希望在转换失败时处理异常,则可以改为调用 Double.TryParse 方法。If you prefer not to handle an exception if the conversion fails, you can call the Double.TryParse method instead. 它将返回一个 Boolean 值,该值指示转换是成功还是失败。It returns a Boolean value that indicates whether the conversion succeeded or failed.
适用于
ToDouble(SByte)
重要
此 API 不符合 CLS。
将指定的 8 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 8-bit signed integer to the equivalent double-precision floating-point number.
public:
static double ToDouble(System::SByte value);
[System.CLSCompliant(false)]
public static double ToDouble (sbyte value);
[<System.CLSCompliant(false)>]
static member ToDouble : sbyte -> double
Public Shared Function ToDouble (value As SByte) As Double
参数
- value
- SByte
要转换的 8 位带符号整数。The 8-bit signed integer to convert.
返回
与 value 等效的 8 位带符号整数。The 8-bit signed integer that is equivalent to value.
- 属性
示例
下面的示例将值数组中的每个元素转换 SByte 为一个 Double 值。The following example converts each element in an array of SByte values to a Double value.
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.
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.
适用于
ToDouble(Object)
将指定对象的值转换为双精度浮点数。Converts the value of the specified object to a double-precision floating-point number.
public:
static double ToDouble(System::Object ^ value);
public static double ToDouble (object value);
public static double ToDouble (object? value);
static member ToDouble : obj -> double
Public Shared Function ToDouble (value As Object) As Double
参数
- value
- Object
用于实现 IConvertible 接口的对象,或为 null。An object that implements the IConvertible interface, or null.
返回
与 value 等效的双精度浮点数,如果 value 为 null,则为零。A double-precision floating-point number that is equivalent to value, or zero if value is null.
例外
value 不实现 IConvertible 接口。value does not implement the IConvertible interface.
或-or-
不支持该转换。The conversion is not supported.
value 表示一个小于 MinValue 或大于 MaxValue 的数字。value represents a number that is less than MinValue or greater than MaxValue.
示例
下面的示例尝试将对象数组中的每个值转换为 Double 。The following example attempts to convert each value in an object array to a 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.
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.
注解
如果不 value 为 null ,则此方法包装对的 IConvertible.ToDouble 基础类型的实现的调用 value 。If value is not null, this method wraps a call to the IConvertible.ToDouble implementation of the underlying type of value.
适用于
ToDouble(Single)
将指定的单精度浮点数的值转换为等效的双精度浮点数。Converts the value of the specified single-precision floating-point number to an equivalent double-precision floating-point number.
public:
static double ToDouble(float value);
public static double ToDouble (float value);
static member ToDouble : single -> double
Public Shared Function ToDouble (value As Single) As Double
参数
- value
- Single
单精度浮点数。The single-precision floating-point number.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
示例
下面的示例将 Single 值转换为 Double 值。The following example converts a Single value to a Double value.
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);
}
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
另请参阅
适用于
ToDouble(Int32)
将指定的 32 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 32-bit signed integer to an equivalent double-precision floating-point number.
public:
static double ToDouble(int value);
public static double ToDouble (int value);
static member ToDouble : int -> double
Public Shared Function ToDouble (value As Integer) As Double
参数
- value
- Int32
要转换的 32 位带符号整数。The 32-bit signed integer to convert.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
示例
下面的示例将 Int32 值转换为 Double 值。The following example converts an Int32 value to a Double value.
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);
}
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
适用于
ToDouble(Int16)
将指定的 16 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 16-bit signed integer to an equivalent double-precision floating-point number.
public:
static double ToDouble(short value);
public static double ToDouble (short value);
static member ToDouble : int16 -> double
Public Shared Function ToDouble (value As Short) As Double
参数
- value
- Int16
要转换的 16 位带符号整数。The 16-bit signed integer to convert.
返回
与 value 等效的双精度浮点数。A double-precision floating-point number equivalent to value.
示例
下面的示例将16位带符号整数数组中的每个元素转换为一个 Double 值。The following example converts each element in an array of 16-bit signed integers to a Double value.
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.
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.
适用于
ToDouble(Double)
返回指定的双精度浮点数;不执行任何实际的转换。Returns the specified double-precision floating-point number; no actual conversion is performed.
public:
static double ToDouble(double value);
public static double ToDouble (double value);
static member ToDouble : double -> double
Public Shared Function ToDouble (value As Double) As Double
参数
- value
- Double
要返回的双精度浮点数。The double-precision floating-point number to return.
返回
不经更改即返回 value。value is returned unchanged.
另请参阅
适用于
ToDouble(Decimal)
将指定的十进制数的值转换为等效的双精度浮点数。Converts the value of the specified decimal number to an equivalent double-precision floating-point number.
public:
static double ToDouble(System::Decimal value);
public static double ToDouble (decimal value);
static member ToDouble : decimal -> double
Public Shared Function ToDouble (value As Decimal) As Double
参数
- value
- Decimal
要转换的十进制数。The decimal number to convert.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
示例
下面的示例将 Decimal 值转换为 Double 值。The following example converts a Decimal value to a Double value.
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.");
}
}
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
适用于
ToDouble(DateTime)
调用此方法始终引发 InvalidCastException。Calling this method always throws InvalidCastException.
public:
static double ToDouble(DateTime value);
public static double ToDouble (DateTime value);
static member ToDouble : DateTime -> double
Public Shared Function ToDouble (value As DateTime) As Double
参数
- value
- DateTime
要转换的日期和时间值。The date and time value to convert.
返回
不支持此转换。This conversion is not supported. 不返回任何值。No value is returned.
例外
不支持此转换。This conversion is not supported.
适用于
ToDouble(Char)
调用此方法始终引发 InvalidCastException。Calling this method always throws InvalidCastException.
public:
static double ToDouble(char value);
public static double ToDouble (char value);
static member ToDouble : char -> double
Public Shared Function ToDouble (value As Char) As Double
参数
- value
- Char
要转换的 Unicode 字符。The Unicode character to convert.
返回
不支持此转换。This conversion is not supported. 不返回任何值。No value is returned.
例外
不支持此转换。This conversion is not supported.
另请参阅
适用于
ToDouble(Byte)
将指定的 8 位无符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 8-bit unsigned integer to the equivalent double-precision floating-point number.
public:
static double ToDouble(System::Byte value);
public static double ToDouble (byte value);
static member ToDouble : byte -> double
Public Shared Function ToDouble (value As Byte) As Double
参数
- value
- Byte
要转换的 8 位无符号整数。The 8-bit unsigned integer to convert.
返回
与 value 等效的双精度浮点数。The double-precision floating-point number that is equivalent to value.
示例
下面的示例将 Byte 值转换为 Double 值。The following example converts a Byte value to a Double value.
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);
}
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
适用于
ToDouble(Boolean)
将指定的布尔值转换为等效的双精度浮点数。Converts the specified Boolean value to the equivalent double-precision floating-point number.
public:
static double ToDouble(bool value);
public static double ToDouble (bool value);
static member ToDouble : bool -> double
Public Shared Function ToDouble (value As Boolean) As Double
参数
- value
- Boolean
要转换的布尔值。The Boolean value to convert.
返回
如果 value 为 true,则为数字 1;否则,为 0。The number 1 if value is true; otherwise, 0.
示例
下面的示例将 Boolean 值转换为 Double 值。The following example converts a Boolean value to a Double value.
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);
}
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
适用于
ToDouble(Int64)
将指定的 64 位带符号整数的值转换为等效的双精度浮点数。Converts the value of the specified 64-bit signed integer to an equivalent double-precision floating-point number.
public:
static double ToDouble(long value);
public static double ToDouble (long value);
static member ToDouble : int64 -> double
Public Shared Function ToDouble (value As Long) As Double
参数
- value
- Int64
要转换的 64 位带符号整数。The 64-bit signed integer to convert.
返回
一个等于 value 的双精度浮点数。A double-precision floating-point number that is equivalent to value.
示例
下面的示例将带符号长整数数组中的每个元素转换为一个 Double 值。The following example converts each element in an array of signed long integers to a Double value.
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.
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.