# Convert.ToBoolean 方法

## 多載

 將指定的 8 位元帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 8-bit signed integer to an equivalent Boolean value. 使用指定之特定文化特性格式資訊，將指定之邏輯值的字串表示轉換為相等的布林值。Converts the specified string representation of a logical value to its Boolean equivalent, using the specified culture-specific formatting information. 使用指定之特定文化特性格式資訊，將指定之物件的值轉換為相等的布林值。Converts the value of the specified object to an equivalent Boolean value, using the specified culture-specific formatting information. 將指定的 64 位元不帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 64-bit unsigned integer to an equivalent Boolean value. 將指定的 32 位元不帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 32-bit unsigned integer to an equivalent Boolean value. 將指定的 16 位元不帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 16-bit unsigned integer to an equivalent Boolean value. 將指定之邏輯值的字串表示，轉換為相等的布林值。Converts the specified string representation of a logical value to its Boolean equivalent. 將指定之單精確度浮點數的值，轉換為相等的布林值。Converts the value of the specified single-precision floating-point number to an equivalent Boolean value. 將指定之物件的值轉換為相等的布林值。Converts the value of a specified object to an equivalent Boolean value. 將指定之雙精確度浮點數的值，轉換為相等的布林值。Converts the value of the specified double-precision floating-point number to an equivalent Boolean value. 將指定的 32 位元帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 32-bit signed integer to an equivalent Boolean value. 將指定的 16 位元帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 16-bit signed integer to an equivalent Boolean value. 將指定之十進位數字的值，轉換為相等的布林值。Converts the value of the specified decimal number to an equivalent Boolean value. 呼叫這個方法一律會擲回 InvalidCastException。Calling this method always throws InvalidCastException. 呼叫這個方法一律會擲回 InvalidCastException。Calling this method always throws InvalidCastException. 將指定的 8 位元不帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 8-bit unsigned integer to an equivalent Boolean value. 傳回指定的布林值 (Boolean)；不會執行實際的轉換。Returns the specified Boolean value; no actual conversion is performed. 將指定的 64 位元帶正負號整數的值，轉換為相等的布林值。Converts the value of the specified 64-bit signed integer to an equivalent Boolean value.

## ToBoolean(SByte)

``````public:
static bool ToBoolean(System::SByte value);``````
``````[System.CLSCompliant(false)]
public static bool ToBoolean (sbyte value);``````
``static member ToBoolean : sbyte -> bool``
``Public Shared Function ToBoolean (value As SByte) As Boolean``

value
SByte

### 範例

``````array<SByte>^ numbers = gcnew array<SByte> { SByte::MinValue, -1, 0, 10, 100, SByte::MaxValue };
bool result;

for each (SByte number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-5}  -->  {1}", number, result);
}
// The example displays the following output:
//       -128   -->  True
//       -1     -->  True
//       0      -->  False
//       10     -->  True
//       100    -->  True
//       127    -->  True
``````
``````sbyte[] numbers = { SByte.MinValue, -1, 0, 10, 100, SByte.MaxValue };
bool result;

foreach (sbyte number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-5}  -->  {1}", number, result);
}
// The example displays the following output:
//       -128   -->  True
//       -1     -->  True
//       0      -->  False
//       10     -->  True
//       100    -->  True
//       127    -->  True
``````
``````Dim numbers() As SByte = { SByte.MinValue, -1, 0, 10, 100, SByte.MaxValue }
Dim result As Boolean

For Each number As SByte In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-5}  -->  {1}", number, result)
Next
' The example displays the following output:
'       -128   -->  True
'       -1     -->  True
'       0      -->  False
'       10     -->  True
'       100    -->  True
'       127    -->  True
``````

## ToBoolean(String, IFormatProvider)

``````public:
static bool ToBoolean(System::String ^ value, IFormatProvider ^ provider);``````
``public static bool ToBoolean (string value, IFormatProvider provider);``
``static member ToBoolean : string * IFormatProvider -> bool``
``Public Shared Function ToBoolean (value As String, provider As IFormatProvider) As Boolean``

value
String

provider
IFormatProvider

#### 傳回

`true` 等於 `value` 時為 TrueString，否則，當 `false` 等於 `value`FalseString 時，則為 `null``true` if `value` equals TrueString, or `false` if `value` equals FalseString or `null`.

#### 例外狀況

`value` 不等於 TrueStringFalseString`value` is not equal to TrueString or FalseString.

## ToBoolean(Object, IFormatProvider)

``````public:
static bool ToBoolean(System::Object ^ value, IFormatProvider ^ provider);``````
``public static bool ToBoolean (object value, IFormatProvider provider);``
``static member ToBoolean : obj * IFormatProvider -> bool``
``Public Shared Function ToBoolean (value As Object, provider As IFormatProvider) As Boolean``

value
Object

provider
IFormatProvider

#### 傳回

`true``false`，其會反映為 ToBoolean(IFormatProvider) 的基礎類型所叫用之 `value` 方法所傳回的值。`true` or `false`, which reflects the value returned by invoking the ToBoolean(IFormatProvider) method for the underlying type of `value`. 如果 `value``null`，則方法會傳回 `false`If `value` is `null`, the method returns `false`.

#### 例外狀況

`value` 是字串，不等於 TrueStringFalseString`value` is a string that does not equal TrueString or FalseString.

`value` 未實作 IConvertible 介面。`value` does not implement the IConvertible interface.

-或--or- 不支援將 `value` 轉換成 BooleanThe conversion of `value` to a Boolean is not supported.

### 範例

``````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 );
}

{
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 )
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
else

// For median averaging, ToBoolean is true if any
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
{
}
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 );
}

public int Add( double 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 )
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
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
{
}
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

Public Function Add( value As Double ) As Integer
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
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
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
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
``````

### 備註

`provider` 可讓使用者指定有關 `value`內容的特定文化特性轉換資訊。`provider` enables the user to specify culture-specific conversion information about the contents of `value`. 基底類型會忽略 `provider` 參數;不過，如果 `value` 是用來執行 IConvertible 介面的使用者定義型別，則可以使用參數。The base types ignore the `provider` parameter; however, the parameter may be used if `value` is a user-defined type that implements the IConvertible interface.

## ToBoolean(UInt64)

``````public:
static bool ToBoolean(System::UInt64 value);``````
``````[System.CLSCompliant(false)]
public static bool ToBoolean (ulong value);``````
``static member ToBoolean : uint64 -> bool``
``Public Shared Function ToBoolean (value As ULong) As Boolean``

value
UInt64

### 範例

``````array<UInt64>^ numbers = gcnew array<UInt64> { UInt64::MinValue, 6121, 403890774, UInt64::MaxValue };
bool result;

for each (UInt64 number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-26:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       0                           -->  False
//       6,121                       -->  True
//       403,890,774                 -->  True
//       18,446,744,073,709,551,615  -->  True
``````
``````ulong[] numbers = { UInt64.MinValue, 6121, 403890774, UInt64.MaxValue };
bool result;

foreach (ulong number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-26:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       0                           -->  False
//       6,121                       -->  True
//       403,890,774                 -->  True
//       18,446,744,073,709,551,615  -->  True
``````
``````Dim numbers() As ULong = { UInt64.MinValue, 6121, 403890774, UInt64.MaxValue }
Dim result As Boolean

For Each number As ULong In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-26:N0}  -->  {1}", number, result)
Next
' The example displays the following output:
'       0                           -->  False
'       6,121                       -->  True
'       403,890,774                 -->  True
'       18,446,744,073,709,551,615  -->  True
``````

## ToBoolean(UInt32)

``````public:
static bool ToBoolean(System::UInt32 value);``````
``````[System.CLSCompliant(false)]
public static bool ToBoolean (uint value);``````
``static member ToBoolean : uint32 -> bool``
``Public Shared Function ToBoolean (value As UInteger) As Boolean``

value
UInt32

### 範例

``````array<UInt32>^ numbers = gcnew array<UInt32> { UInt32::MinValue, 612, 4038907, Int32::MaxValue };
bool result;

for each (unsigned int number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-15:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       0                -->  False
//       612              -->  True
//       4,038,907        -->  True
//       2,147,483,647    -->  True
``````
``````uint[] numbers = { UInt32.MinValue, 612, 4038907, Int32.MaxValue };
bool result;

foreach (uint number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-15:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       0                -->  False
//       612              -->  True
//       4,038,907        -->  True
//       2,147,483,647    -->  True
``````
``````Dim numbers() As UInteger = { UInt32.MinValue, 612, 4038907, Int32.MaxValue }
Dim result As Boolean

For Each number As UInteger In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-15:N0}  -->  {1}", number, result)
Next
' The example displays the following output:
'       0                -->  False
'       612              -->  True
'       4,038,907        -->  True
'       2,147,483,647    -->  True
``````

## ToBoolean(UInt16)

``````public:
static bool ToBoolean(System::UInt16 value);``````
``````[System.CLSCompliant(false)]
public static bool ToBoolean (ushort value);``````
``static member ToBoolean : uint16 -> bool``
``Public Shared Function ToBoolean (value As UShort) As Boolean``

value
UInt16

### 範例

``````array<unsigned short>^ numbers = gcnew array<unsigned short> { UInt16::MinValue, 216, 21453, UInt16::MaxValue };
bool result;

for each (unsigned short number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-7:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       0        -->  False
//       216      -->  True
//       21,453   -->  True
//       65,535   -->  True
``````
``````ushort[] numbers = { UInt16.MinValue, 216, 21453, UInt16.MaxValue };
bool result;

foreach (ushort number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-7:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       0        -->  False
//       216      -->  True
//       21,453   -->  True
//       65,535   -->  True
``````
``````Dim numbers() As UShort = { UInt16.MinValue, 216, 21453, UInt16.MaxValue }
Dim result As Boolean

For Each number As UShort In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-7:N0}  -->  {1}", number, result)
Next
' The example displays the following output:
'       0        -->  False
'       216      -->  True
'       21,453   -->  True
'       65,535   -->  True
``````

## ToBoolean(String)

``````public:
static bool ToBoolean(System::String ^ value);``````
``public static bool ToBoolean (string value);``
``static member ToBoolean : string -> bool``
``Public Shared Function ToBoolean (value As String) As Boolean``

value
String

#### 傳回

`true` 等於 `value` 時為 TrueString，否則，當 `false` 等於 `value`FalseString 時，則為 `null``true` if `value` equals TrueString, or `false` if `value` equals FalseString or `null`.

#### 例外狀況

`value` 不等於 TrueStringFalseString`value` is not equal to TrueString or FalseString.

### 範例

``````using namespace System;

void main()
{
array<String^>^ values = gcnew array<String^> { nullptr, String::Empty,
"true", "TrueString",
"False", "    false    ",
"-1", "0" };
for each (String^ value in values) {
try
{
Console::WriteLine("Converted '{0}' to {1}.", value,
Convert::ToBoolean(value));
}
catch (FormatException^ e)
{
Console::WriteLine("Unable to convert '{0}' to a Boolean.", value);
}
}
}
// The example displays the following output:
//       Converted '' to False.
//       Unable to convert '' to a Boolean.
//       Converted 'true' to True.
//       Unable to convert 'TrueString' to a Boolean.
//       Converted 'False' to False.
//       Converted '    false    ' to False.
//       Unable to convert '-1' to a Boolean.
//       Unable to convert '0' to a Boolean.
``````
``````using System;

public class BooleanConversion
{
public static void Main()
{
String[] values = { null, String.Empty, "true", "TrueString",
"False", "    false    ", "-1", "0" };
foreach (var value in values) {
try
{
Console.WriteLine("Converted '{0}' to {1}.", value,
Convert.ToBoolean(value));
}
catch (FormatException)
{
Console.WriteLine("Unable to convert '{0}' to a Boolean.", value);
}
}
}
}
// The example displays the following output:
//       Converted '' to False.
//       Unable to convert '' to a Boolean.
//       Converted 'true' to True.
//       Unable to convert 'TrueString' to a Boolean.
//       Converted 'False' to False.
//       Converted '    false    ' to False.
//       Unable to convert '-1' to a Boolean.
//       Unable to convert '0' to a Boolean.
``````
``````Module BooleanConversion
Public Sub Main()
Dim values() As String = { Nothing, String.Empty, "true",
"TrueString", "False", "    false    ",
"-1", "0" }
For Each value In values
Try
Console.WriteLine("Converted '{0}' to {1}.", value, _
Convert.ToBoolean(value))
Catch e As FormatException
Console.WriteLine("Unable to convert '{0}' to a Boolean.", value)
End Try
Next
End Sub
End Module
' The example displays the following output to the console:
'       Converted '' to False.
'       Unable to convert '' to a Boolean.
'       Converted 'true' to True.
'       Unable to convert 'TrueString' to a Boolean.
'       Converted 'False' to False.
'       Converted '    false    ' to False.
'       Unable to convert '-1' to a Boolean.
'       Unable to convert '0' to a Boolean.
``````

## ToBoolean(Single)

``````public:
static bool ToBoolean(float value);``````
``public static bool ToBoolean (float value);``
``static member ToBoolean : single -> bool``
``Public Shared Function ToBoolean (value As Single) As Boolean``

value
Single

### 範例

``````array<float>^ numbers = gcnew array<float> { Single::MinValue, (float) -193.0012, (float) 20e-15f, 0,
(float) 10551e-10, (float) 100.3398, Single::MaxValue };
bool result;

for each (float number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-15}  -->  {1}", number, result);
}
// The example displays the following output:
//       -3.402823E+38    -->  True
//       -193.0012        -->  True
//       2E-14            -->  True
//       0                -->  False
//       1.0551E-06       -->  True
//       100.3398         -->  True
//       3.402823E+38     -->  True
``````
``````float[] numbers = { Single.MinValue, -193.0012f, 20e-15f, 0f,
10551e-10f, 100.3398f, Single.MaxValue };
bool result;

foreach (float number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-15}  -->  {1}", number, result);
}
// The example displays the following output:
//       -3.402823E+38    -->  True
//       -193.0012        -->  True
//       2E-14            -->  True
//       0                -->  False
//       1.0551E-06       -->  True
//       100.3398         -->  True
//       3.402823E+38     -->  True
``````
``````Dim numbers() As Single = { Single.MinValue, -193.0012, 20e-15, 0, _
10551e-10, 100.3398, Single.MaxValue }
Dim result As Boolean

For Each number As Single In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-15}  -->  {1}", number, result)
Next
' The example displays the following output:
'       -3.402823E+38    -->  True
'       -193.0012        -->  True
'       2E-14            -->  True
'       0                -->  False
'       1.0551E-06       -->  True
'       100.3398         -->  True
'       3.402823E+38     -->  True
``````

## ToBoolean(Object)

``````public:
static bool ToBoolean(System::Object ^ value);``````
``public static bool ToBoolean (object value);``
``static member ToBoolean : obj -> bool``
``Public Shared Function ToBoolean (value As Object) As Boolean``

value
Object

#### 傳回

`true``false`，其會反映為 ToBoolean(IFormatProvider) 的基礎類型所叫用之 `value` 方法所傳回的值。`true` or `false`, which reflects the value returned by invoking the ToBoolean(IFormatProvider) method for the underlying type of `value`. 如果 `value``null`，則方法會傳回 `false`If `value` is `null`, the method returns `false`.

#### 例外狀況

`value` 是字串，不等於 TrueStringFalseString`value` is a string that does not equal TrueString or FalseString.

`value` 未實作 IConvertible 介面。`value` does not implement the IConvertible interface.

-或--or- 不支援將 `value` 轉換成 BooleanThe conversion of `value` to a Boolean is not supported.

### 範例

``````array<Object^>^ objects = gcnew array<Object^> { 16.33, -24, 0, "12", "12.7", String::Empty,
"1String", "True", "false", nullptr,
gcnew System::Collections::ArrayList };

for each (Object^ obj in objects)
{
Console::Write("{0,-40}  -->  ",
obj == nullptr ? "null" :
String::Format("{0} ({1})", obj, obj->GetType()->Name));
try {
Console::WriteLine("{0}", Convert::ToBoolean((Object^) obj));
}
catch (FormatException^) {
}
catch (InvalidCastException^) {
Console::WriteLine("No Conversion");
}
}
// The example displays the following output:
//       16.33 (Double)                            -->  True
//       -24 (Int32)                               -->  True
//       0 (Int32)                                 -->  False
//       12 (String)                               -->  Bad Format
//       12.7 (String)                             -->  Bad Format
//       1String (String)                          -->  Bad Format
//       True (String)                             -->  True
//       false (String)                            -->  False
//       null                                      -->  False
//       System.Collections.ArrayList (ArrayList)  -->  No Conversion
``````
``````object[] objects = { 16.33, -24, 0, "12", "12.7", String.Empty,
"1String", "True", "false", null,
new System.Collections.ArrayList() };

foreach (object obj in objects)
{
Console.Write("{0,-40}  -->  ",
obj != null ?
String.Format("{0} ({1})", obj, obj.GetType().Name) :
"null");
try {
Console.WriteLine("{0}", Convert.ToBoolean(obj));
}
catch (FormatException) {
}
catch (InvalidCastException) {
Console.WriteLine("No Conversion");
}
}
// The example displays the following output:
//       16.33 (Double)                            -->  True
//       -24 (Int32)                               -->  True
//       0 (Int32)                                 -->  False
//       12 (String)                               -->  Bad Format
//       12.7 (String)                             -->  Bad Format
//       1String (String)                          -->  Bad Format
//       True (String)                             -->  True
//       false (String)                            -->  False
//       null                                      -->  False
//       System.Collections.ArrayList (ArrayList)  -->  No Conversion
``````
``````Dim objects() As Object = {16.33, -24, 0, "12", "12.7", String.Empty, _
"1String", "True", "false", Nothing, _
New System.Collections.ArrayList() }
For Each obj As Object In objects
If obj IsNot Nothing Then
Console.Write("{0,-40}  -->  ", _
String.Format("{0} ({1})", obj, obj.GetType().Name))
Else
Console.Write("{0,-40}  -->  ", "Nothing")
End If
Try
Console.WriteLine("{0}", Convert.ToBoolean(obj))
Catch e As FormatException
Catch e As InvalidCastException
Console.WriteLine("No Conversion")
End Try
Next
' The example displays the following output:
'       16.33 (Double)                            -->  True
'       -24 (Int32)                               -->  True
'       0 (Int32)                                 -->  False
'       12 (String)                               -->  Bad Format
'       12.7 (String)                             -->  Bad Format
'       1String (String)                          -->  Bad Format
'       True (String)                             -->  True
'       false (String)                            -->  False
'       Nothing                                   -->  False
'       System.Collections.ArrayList (ArrayList)  -->  No Conversion
``````

## ToBoolean(Double)

``````public:
static bool ToBoolean(double value);``````
``public static bool ToBoolean (double value);``
``static member ToBoolean : double -> bool``
``Public Shared Function ToBoolean (value As Double) As Boolean``

value
Double

### 範例

``````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
``````

## ToBoolean(Int32)

``````public:
static bool ToBoolean(int value);``````
``public static bool ToBoolean (int value);``
``static member ToBoolean : int -> bool``
``Public Shared Function ToBoolean (value As Integer) As Boolean``

value
Int32

### 範例

``````array<int>^ numbers = gcnew array<int> { Int32::MinValue, -201649, -68, 0, 612, 4038907,
Int32::MaxValue };
bool result;

for each (int number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-15:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       -2,147,483,648   -->  True
//       -201,649         -->  True
//       -68              -->  True
//       0                -->  False
//       612              -->  True
//       4,038,907        -->  True
//       2,147,483,647    -->  True
``````
``````int[] numbers = { Int32.MinValue, -201649, -68, 0, 612, 4038907,
Int32.MaxValue };
bool result;

foreach (int number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-15:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       -2,147,483,648   -->  True
//       -201,649         -->  True
//       -68              -->  True
//       0                -->  False
//       612              -->  True
//       4,038,907        -->  True
//       2,147,483,647    -->  True
``````
``````Dim numbers() As Integer = { Int32.MinValue, -201649, -68, 0, 612, _
4038907, Int32.MaxValue }
Dim result As Boolean

For Each number As Integer In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-15:N0}  -->  {1}", number, result)
Next
' The example displays the following output:
'       -2,147,483,648   -->  True
'       -201,649         -->  True
'       -68              -->  True
'       0                -->  False
'       612              -->  True
'       4,038,907        -->  True
'       2,147,483,647    -->  True
``````

## ToBoolean(Int16)

``````public:
static bool ToBoolean(short value);``````
``public static bool ToBoolean (short value);``
``static member ToBoolean : int16 -> bool``
``Public Shared Function ToBoolean (value As Short) As Boolean``

value
Int16

### 範例

``````array<Int16>^ numbers = gcnew array<Int16> { Int16::MinValue, -10000, -154, 0, 216, 21453,
Int16::MaxValue };
bool result;

for each (Int16 number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-7:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       -32,768  -->  True
//       -10,000  -->  True
//       -154     -->  True
//       0        -->  False
//       216      -->  True
//       21,453   -->  True
//       32,767   -->  True
``````
``````short[] numbers = { Int16.MinValue, -10000, -154, 0, 216, 21453,
Int16.MaxValue };
bool result;

foreach (short number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-7:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       -32,768  -->  True
//       -10,000  -->  True
//       -154     -->  True
//       0        -->  False
//       216      -->  True
//       21,453   -->  True
//       32,767   -->  True
``````
``````Dim numbers() As Short = { Int16.MinValue, -10000, -154, 0, 216, _
21453, Int16.MaxValue }
Dim result As Boolean

For Each number As Short In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-7:N0}  -->  {1}", number, result)
Next
' The example displays the following output:
'       -32,768  -->  True
'       -10,000  -->  True
'       -154     -->  True
'       0        -->  False
'       216      -->  True
'       21,453   -->  True
'       32,767   -->  True
``````

## ToBoolean(Decimal)

``````public:
static bool ToBoolean(System::Decimal value);``````
``public static bool ToBoolean (decimal value);``
``static member ToBoolean : decimal -> bool``
``Public Shared Function ToBoolean (value As Decimal) As Boolean``

value
Decimal

### 範例

``````array<Decimal>^ numbers = gcnew array<Decimal> { Decimal::MinValue, (Decimal) -12034.87,
(Decimal) -100, (Decimal) 0, (Decimal) 300,
(Decimal) 6790823.45, Decimal::MaxValue };
bool result;

for each (Decimal number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-30}  -->  {1}", number, result);
}
// The example displays the following output:
//       -79228162514264337593543950335  -->  True
//       -12034.87                       -->  True
//       -100                            -->  True
//       0                               -->  False
//       300                             -->  True
//       6790823.45                      -->  True
//       79228162514264337593543950335   -->  True
``````
``````decimal[] numbers = { Decimal.MinValue, -12034.87m, -100m, 0m,
300m, 6790823.45m, Decimal.MaxValue };
bool result;

foreach (decimal number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-30}  -->  {1}", number, result);
}
// The example displays the following output:
//       -79228162514264337593543950335  -->  True
//       -12034.87                       -->  True
//       -100                            -->  True
//       0                               -->  False
//       300                             -->  True
//       6790823.45                      -->  True
//       79228162514264337593543950335   -->  True
``````
``````Dim numbers() As Decimal = { Decimal.MinValue, -12034.87d, -100d, _
0d, 300d, 6790823.45d, Decimal.MaxValue }
Dim result As Boolean

For Each number As Decimal In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-30}  -->  {1}", number, result)
Next
' The example displays the following output:
'       -79228162514264337593543950335  -->  True
'       -12034.87                       -->  True
'       -100                            -->  True
'       0                               -->  False
'       300                             -->  True
'       6790823.45                      -->  True
'       79228162514264337593543950335   -->  True
``````

## ToBoolean(DateTime)

``````public:
static bool ToBoolean(DateTime value);``````
``public static bool ToBoolean (DateTime value);``
``static member ToBoolean : DateTime -> bool``
``Public Shared Function ToBoolean (value As DateTime) As Boolean``

value
DateTime

### 範例

``````public:
void ConvertBoolean()
{
const int year = 1979;
const int month = 7;
const int day = 28;
const int hour = 13;
const int minute = 26;
const int second = 15;
const int millisecond = 53;
DateTime dateTime( year, month, day, hour,
minute, second, millisecond );
bool boolVal;

// System::InvalidCastException is always thrown.
try
{
boolVal = System::Convert::ToBoolean( dateTime );
}
catch ( System::InvalidCastException^ )
{
System::Console::WriteLine( "Conversion from DateTime to Boolean "+
"is not supported by the .NET Framework." );
}
}
``````
``````public void ConvertBoolean() {
const int year			= 1979;
const int month			= 7;
const int day			= 28;
const int hour			= 13;
const int minute		= 26;
const int second		= 15;
const int millisecond	= 53;

DateTime dateTime = new DateTime(year, month, day, hour,
minute, second, millisecond);

bool boolVal;

// System.InvalidCastException is always thrown.
try {
boolVal = System.Convert.ToBoolean(dateTime);
}
catch (System.InvalidCastException) {
System.Console.WriteLine("Conversion from DateTime to " +
"Boolean is not supported by the .NET Framework.");
}
}
``````
``````Public Sub ConvertBoolean()
Const year As Integer = 1979
Const month As Integer = 7
Const day As Integer = 28
Const hour As Integer = 13
Const minute As Integer = 26
Const second As Integer = 15
Const millisecond As Integer = 53

Dim dateTime As New DateTime(year, month, day, hour, minute, _
second, millisecond)

Dim boolVal As Boolean

' System.InvalidCastException is always thrown.
Try
boolVal = System.Convert.ToBoolean(dateTime)
Catch exception As System.InvalidCastException
System.Console.WriteLine("Conversion from DateTime to " + _
"Boolean is not supported by the .NET Framework.")
End Try
End Sub
``````

## ToBoolean(Char)

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

value
Char

## ToBoolean(Byte)

``````public:
static bool ToBoolean(System::Byte value);``````
``public static bool ToBoolean (byte value);``
``static member ToBoolean : byte -> bool``
``Public Shared Function ToBoolean (value As Byte) As Boolean``

value
Byte

### 範例

``````array<Byte>^ bytes = gcnew array<Byte> { Byte::MinValue, 100, 200, Byte::MaxValue };
bool result;

for each (Byte byteValue in bytes)
{
result = Convert::ToBoolean(byteValue);
Console::WriteLine("{0,-5}  -->  {1}", byteValue, result);
}
// The example displays the following output:
//       0      -->  False
//       100    -->  True
//       200    -->  True
//       255    -->  True
``````
``````byte[] bytes = { Byte.MinValue, 100, 200, Byte.MaxValue };
bool result;

foreach (byte byteValue in bytes)
{
result = Convert.ToBoolean(byteValue);
Console.WriteLine("{0,-5}  -->  {1}", byteValue, result);
}
// The example displays the following output:
//       0      -->  False
//       100    -->  True
//       200    -->  True
//       255    -->  True
``````
``````Dim bytes() As Byte = { Byte.MinValue, 100, 200, Byte.MaxValue }
Dim result As Boolean

For Each byteValue As Byte In bytes
result = Convert.ToBoolean(byteValue)
Console.WriteLine("{0,-5}  -->  {1}", byteValue, result)
Next
' The example displays the following output:
'       0      -->  False
'       100    -->  True
'       200    -->  True
'       255    -->  True
``````

## ToBoolean(Boolean)

``````public:
static bool ToBoolean(bool value);``````
``public static bool ToBoolean (bool value);``
``static member ToBoolean : bool -> bool``
``Public Shared Function ToBoolean (value As Boolean) As Boolean``

value
Boolean

#### 傳回

`value` 會原封不動地傳回。`value` is returned unchanged.

## ToBoolean(Int64)

``````public:
static bool ToBoolean(long value);``````
``public static bool ToBoolean (long value);``
``static member ToBoolean : int64 -> bool``
``Public Shared Function ToBoolean (value As Long) As Boolean``

value
Int64

### 範例

``````array<Int64>^ numbers = gcnew array<Int64> { Int64::MinValue, -2016493, -689, 0, 6121,
403890774, Int64::MaxValue };
bool result;

for each (Int64 number in numbers)
{
result = Convert::ToBoolean(number);
Console::WriteLine("{0,-26:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       -9,223,372,036,854,775,808  -->  True
//       -2,016,493                  -->  True
//       -689                        -->  True
//       0                           -->  False
//       6,121                       -->  True
//       403,890,774                 -->  True
//       9,223,372,036,854,775,807   -->  True
``````
``````long[] numbers = { Int64.MinValue, -2016493, -689, 0, 6121,
403890774, Int64.MaxValue };
bool result;

foreach (long number in numbers)
{
result = Convert.ToBoolean(number);
Console.WriteLine("{0,-26:N0}  -->  {1}", number, result);
}
// The example displays the following output:
//       -9,223,372,036,854,775,808  -->  True
//       -2,016,493                  -->  True
//       -689                        -->  True
//       0                           -->  False
//       6,121                       -->  True
//       403,890,774                 -->  True
//       9,223,372,036,854,775,807   -->  True
``````
``````Dim numbers() As Long = { Int64.MinValue, -2016493, -689, 0, 6121, _
403890774, Int64.MaxValue }
Dim result As Boolean

For Each number As Long In numbers
result = Convert.ToBoolean(number)
Console.WriteLine("{0,-26:N0}  -->  {1}", number, result)
Next
' The example displays the following output:
'       -9,223,372,036,854,775,808  -->  True
'       -2,016,493                  -->  True
'       -689                        -->  True
'       0                           -->  False
'       6,121                       -->  True
'       403,890,774                 -->  True
'       9,223,372,036,854,775,807   -->  True
``````