Convert.ToBoolean Convert.ToBoolean Convert.ToBoolean Convert.ToBoolean Method

Определение

Преобразует заданное значение в эквивалентное логическое значение.Converts a specified value to an equivalent Boolean value.

Перегрузки

ToBoolean(SByte) ToBoolean(SByte) ToBoolean(SByte) ToBoolean(SByte)

Преобразует значение заданного 8-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 8-bit signed integer to an equivalent Boolean value.

ToBoolean(String, IFormatProvider) ToBoolean(String, IFormatProvider) ToBoolean(String, IFormatProvider) ToBoolean(String, IFormatProvider)

Преобразует заданное строковое представление логического значения в эквивалентное логическое значение, используя указанные сведения об особенностях форматирования, связанных с языком и региональными параметрами.Converts the specified string representation of a logical value to its Boolean equivalent, using the specified culture-specific formatting information.

ToBoolean(Object, IFormatProvider) ToBoolean(Object, IFormatProvider) ToBoolean(Object, IFormatProvider) ToBoolean(Object, IFormatProvider)

Преобразует значение заданного объекта в эквивалентное логическое значение, используя указанные сведения об особенностях форматирования, связанных с языком и региональными параметрами.Converts the value of the specified object to an equivalent Boolean value, using the specified culture-specific formatting information.

ToBoolean(UInt64) ToBoolean(UInt64) ToBoolean(UInt64) ToBoolean(UInt64)

Преобразует значение заданного 64-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 64-bit unsigned integer to an equivalent Boolean value.

ToBoolean(UInt32) ToBoolean(UInt32) ToBoolean(UInt32) ToBoolean(UInt32)

Преобразует значение заданного 32-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 32-bit unsigned integer to an equivalent Boolean value.

ToBoolean(UInt16) ToBoolean(UInt16) ToBoolean(UInt16) ToBoolean(UInt16)

Преобразует значение заданного 16-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 16-bit unsigned integer to an equivalent Boolean value.

ToBoolean(String) ToBoolean(String) ToBoolean(String) ToBoolean(String)

Преобразует заданное строковое представление логического значения в эквивалентное логическое значение.Converts the specified string representation of a logical value to its Boolean equivalent.

ToBoolean(Single) ToBoolean(Single) ToBoolean(Single) ToBoolean(Single)

Преобразует значение заданного числа с плавающей запятой одиночной точности в эквивалентное логическое значение.Converts the value of the specified single-precision floating-point number to an equivalent Boolean value.

ToBoolean(Object) ToBoolean(Object) ToBoolean(Object) ToBoolean(Object)

Преобразует значение заданного объекта в эквивалентное логическое значение.Converts the value of a specified object to an equivalent Boolean value.

ToBoolean(Double) ToBoolean(Double) ToBoolean(Double) ToBoolean(Double)

Преобразует значение заданного числа двойной точности с плавающей запятой в эквивалентное логическое значение.Converts the value of the specified double-precision floating-point number to an equivalent Boolean value.

ToBoolean(Int32) ToBoolean(Int32) ToBoolean(Int32) ToBoolean(Int32)

Преобразует значение заданного 32-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 32-bit signed integer to an equivalent Boolean value.

ToBoolean(Int16) ToBoolean(Int16) ToBoolean(Int16) ToBoolean(Int16)

Преобразует значение заданного 16-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 16-bit signed integer to an equivalent Boolean value.

ToBoolean(Decimal) ToBoolean(Decimal) ToBoolean(Decimal) ToBoolean(Decimal)

Преобразует значение заданного десятичного числа в эквивалентное логическое значение.Converts the value of the specified decimal number to an equivalent Boolean value.

ToBoolean(DateTime) ToBoolean(DateTime) ToBoolean(DateTime) ToBoolean(DateTime)

При вызове этого метода всегда возникает исключение InvalidCastException.Calling this method always throws InvalidCastException.

ToBoolean(Char) ToBoolean(Char) ToBoolean(Char) ToBoolean(Char)

При вызове этого метода всегда возникает исключение InvalidCastException.Calling this method always throws InvalidCastException.

ToBoolean(Byte) ToBoolean(Byte) ToBoolean(Byte) ToBoolean(Byte)

Преобразует значение заданного 8-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 8-bit unsigned integer to an equivalent Boolean value.

ToBoolean(Boolean) ToBoolean(Boolean) ToBoolean(Boolean) ToBoolean(Boolean)

Возвращает заданное логическое значение; фактическое преобразование не производится.Returns the specified Boolean value; no actual conversion is performed.

ToBoolean(Int64) ToBoolean(Int64) ToBoolean(Int64) ToBoolean(Int64)

Преобразует значение заданного 64-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 64-bit signed integer to an equivalent Boolean value.

ToBoolean(SByte) ToBoolean(SByte) ToBoolean(SByte) ToBoolean(SByte)

Важно!

Этот API несовместим с CLS.

Преобразует значение заданного 8-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 8-bit signed integer to an equivalent Boolean value.

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

Параметры

value
SByte SByte SByte SByte

8-разрядное целое число со знаком для преобразования.The 8-bit signed integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив SByte значения Boolean значения.The following example converts an array of SByte values to Boolean values.

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
Дополнительно

ToBoolean(String, IFormatProvider) ToBoolean(String, IFormatProvider) ToBoolean(String, IFormatProvider) ToBoolean(String, IFormatProvider)

Преобразует заданное строковое представление логического значения в эквивалентное логическое значение, используя указанные сведения об особенностях форматирования, связанных с языком и региональными параметрами.Converts the specified string representation of a logical value to its Boolean equivalent, using the specified culture-specific formatting information.

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

Параметры

value
String String String String

Строка, содержащая значение TrueString или FalseString.A string that contains the value of either TrueString or FalseString.

provider
IFormatProvider IFormatProvider IFormatProvider IFormatProvider

Объект, предоставляющий сведения о форматировании для определенного языка и региональных параметров.An object that supplies culture-specific formatting information. Этот параметр не учитывается.This parameter is ignored.

Возвраты

true, если параметр value имеет значение TrueString, или false, если параметр value имеет значение FalseString либо null.true if value equals TrueString, or false if value equals FalseString or null.

Исключения

Параметр value не равен TrueString или FalseString.value is not equal to TrueString or FalseString.

Комментарии

Если вы не хотите обрабатывать исключение, если преобразование завершается неудачей, можно вызвать Boolean.TryParse метод вместо этого.If you prefer not to handle an exception if the conversion fails, you can call the Boolean.TryParse method instead. Он возвращает Boolean значение, указывающее, успешно ли выполнено преобразование.It returns a Boolean value that indicates whether the conversion succeeded or failed.

Дополнительно

ToBoolean(Object, IFormatProvider) ToBoolean(Object, IFormatProvider) ToBoolean(Object, IFormatProvider) ToBoolean(Object, IFormatProvider)

Преобразует значение заданного объекта в эквивалентное логическое значение, используя указанные сведения об особенностях форматирования, связанных с языком и региональными параметрами.Converts the value of the specified object to an equivalent Boolean value, using the specified culture-specific formatting information.

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

Параметры

value
Object Object Object Object

Объект, реализующий интерфейс IConvertible, или значение null.An object that implements the IConvertible interface, or null.

provider
IFormatProvider IFormatProvider IFormatProvider IFormatProvider

Объект, предоставляющий сведения о форматировании для определенного языка и региональных параметров.An object that supplies culture-specific formatting information.

Возвраты

true или false, отражающее значение, возвращаемое методом ToBoolean(IFormatProvider) при вызове для базового типа параметра value.true or false, which reflects the value returned by invoking the ToBoolean(IFormatProvider) method for the underlying type of value. Если значением параметра value является null, метод возвращает false.If value is null, the method returns false.

Исключения

value является строкой, которая не равна TrueString или FalseString.value is a string that does not equal TrueString or FalseString.

value не реализует интерфейс IConvertible.value does not implement the IConvertible interface.

-или--or- Преобразование value в Boolean не поддерживается.The conversion of value to a Boolean is not supported.

Примеры

В следующем примере определяется класс, реализующий IConvertible и класс, реализующий IFormatProvider.The following example defines a class that implements IConvertible and a class that implements IFormatProvider. Объекты класса, реализующего IConvertible содержат массив Double значения.Objects of the class that implements IConvertible hold an array of Double values. Объект каждого класса передается ToBoolean(Object, IFormatProvider) метод.An object of each class is passed to the ToBoolean(Object, IFormatProvider) method. Этот метод возвращает true Если любое из значений не игнорируемые массива не равны нулю.This method returns true if any of the non-discarded array values are non-zero. IFormatProvider Объект определяет, как для этого вычисления удаляются элементы.The IFormatProvider object determines how elements are discarded for this calculation.

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

Комментарии

provider позволяет пользователю указать сведения о преобразовании региональных содержимое value.provider enables the user to specify culture-specific conversion information about the contents of value. Базовые типы игнорируют provider параметр; тем не менее, если может использоваться параметр value является определяемого пользователем типа, который реализует IConvertible интерфейс.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.

Дополнительно

ToBoolean(UInt64) ToBoolean(UInt64) ToBoolean(UInt64) ToBoolean(UInt64)

Важно!

Этот API несовместим с CLS.

Преобразует значение заданного 64-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 64-bit unsigned integer to an equivalent Boolean value.

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

Параметры

value
UInt64 UInt64 UInt64 UInt64

64-разрядное целое число без знака для преобразования.The 64-bit unsigned integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив UInt64 значения Boolean значения.The following example converts an array of UInt64 values to Boolean values.

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
Дополнительно

ToBoolean(UInt32) ToBoolean(UInt32) ToBoolean(UInt32) ToBoolean(UInt32)

Важно!

Этот API несовместим с CLS.

Преобразует значение заданного 32-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 32-bit unsigned integer to an equivalent Boolean value.

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

Параметры

value
UInt32 UInt32 UInt32 UInt32

32-разрядное целое число без знака для преобразования.The 32-bit unsigned integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Int32 значения Boolean значения.The following example converts an array of Int32 values to Boolean values.

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
Дополнительно

ToBoolean(UInt16) ToBoolean(UInt16) ToBoolean(UInt16) ToBoolean(UInt16)

Важно!

Этот API несовместим с CLS.

Преобразует значение заданного 16-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 16-bit unsigned integer to an equivalent Boolean value.

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

Параметры

value
UInt16 UInt16 UInt16 UInt16

16-разрядное целое число без знака для преобразования.The 16-bit unsigned integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив UInt16 значения Boolean значения.The following example converts an array of UInt16 values to Boolean values.

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
Дополнительно

ToBoolean(String) ToBoolean(String) ToBoolean(String) ToBoolean(String)

Преобразует заданное строковое представление логического значения в эквивалентное логическое значение.Converts the specified string representation of a logical value to its Boolean equivalent.

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

Параметры

value
String String String String

Строка, содержащая значение TrueString или FalseString.A string that contains the value of either TrueString or FalseString.

Возвраты

true, если параметр value имеет значение TrueString, или false, если параметр value имеет значение FalseString либо null.true if value equals TrueString, or false if value equals FalseString or null.

Исключения

Параметр value не равен TrueString или FalseString.value is not equal to TrueString or FalseString.

Примеры

В следующем примере используется Convert.ToBoolean(String) метод для преобразования различных строк в логические значения.The following example uses the Convert.ToBoolean(String) method to convert various strings to Boolean values.

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.

Комментарии

Для успешного преобразования возникает value параметра должно быть равно либо Boolean.TrueString, константа, значение которого представляет собой True, Boolean.FalseString, константа, значение которого представляет собой False, или он должен быть null.For a successful conversion to occur, the value parameter must equal either Boolean.TrueString, a constant whose value is True, Boolean.FalseString, a constant whose value is False, or it must be null. При сравнении value с Boolean.TrueString и Boolean.FalseString, метод не учитывает регистр также как начальные и конечные пробелы.In comparing value with Boolean.TrueString and Boolean.FalseString, the method ignores case as well as leading and trailing white space.

Если вы не хотите обрабатывать исключение, если преобразование завершается неудачей, можно вызвать Boolean.TryParse метод вместо этого.If you prefer not to handle an exception if the conversion fails, you can call the Boolean.TryParse method instead. Он возвращает Boolean значение, указывающее, успешно ли выполнено преобразование.It returns a Boolean value that indicates whether the conversion succeeded or failed.

Дополнительно

ToBoolean(Single) ToBoolean(Single) ToBoolean(Single) ToBoolean(Single)

Преобразует значение заданного числа с плавающей запятой одиночной точности в эквивалентное логическое значение.Converts the value of the specified single-precision floating-point number to an equivalent Boolean value.

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

Параметры

value
Single Single Single Single

Число с плавающей запятой одиночной точности, которое нужно преобразовать.The single-precision floating-point number to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Single значения Boolean значения.The following example converts an array of Single values to Boolean values.

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
Дополнительно

ToBoolean(Object) ToBoolean(Object) ToBoolean(Object) ToBoolean(Object)

Преобразует значение заданного объекта в эквивалентное логическое значение.Converts the value of a specified object to an equivalent Boolean value.

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

Параметры

value
Object Object Object Object

Объект, реализующий интерфейс IConvertible, или значение null.An object that implements the IConvertible interface, or null.

Возвраты

true или false, отражающее значение, возвращаемое методом ToBoolean(IFormatProvider) при вызове для базового типа параметра value.true or false, which reflects the value returned by invoking the ToBoolean(IFormatProvider) method for the underlying type of value. Если значением параметра value является null, метод возвращает false.If value is null, the method returns false.

Исключения

value является строкой, которая не равна TrueString или FalseString.value is a string that does not equal TrueString or FalseString.

value не реализует интерфейс IConvertible.value does not implement the IConvertible interface.

-или--or- Преобразование value в Boolean не поддерживается.The conversion of value to a Boolean is not supported.

Примеры

В следующем примере преобразуется в массив значений объектов для Boolean значения.The following example converts an array of object values to Boolean values.

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^) {
      Console::WriteLine("Bad Format");
   }   
   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
//        (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) {
      Console.WriteLine("Bad Format");
   }   
   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
//        (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
      Console.WriteLine("Bad Format")
   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
'        (String)                                 -->  Bad Format
'       1String (String)                          -->  Bad Format
'       True (String)                             -->  True
'       false (String)                            -->  False
'       Nothing                                   -->  False
'       System.Collections.ArrayList (ArrayList)  -->  No Conversion
Дополнительно

ToBoolean(Double) ToBoolean(Double) ToBoolean(Double) ToBoolean(Double)

Преобразует значение заданного числа двойной точности с плавающей запятой в эквивалентное логическое значение.Converts the value of the specified double-precision floating-point number to an equivalent Boolean value.

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

Параметры

value
Double Double Double Double

Число с плавающей запятой двойной точности, которое нужно преобразовать.The double-precision floating-point number to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в логическое значение, Double и Double в значение типа Boolean.The following example converts a Boolean to a Double and a Double to a Boolean 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
Дополнительно

ToBoolean(Int32) ToBoolean(Int32) ToBoolean(Int32) ToBoolean(Int32)

Преобразует значение заданного 32-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 32-bit signed integer to an equivalent Boolean value.

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

Параметры

value
Int32 Int32 Int32 Int32

32-разрядное целое число со знаком для преобразования.The 32-bit signed integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Int32 значения Boolean значения.The following example converts an array of Int32 values to Boolean values.

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
Дополнительно

ToBoolean(Int16) ToBoolean(Int16) ToBoolean(Int16) ToBoolean(Int16)

Преобразует значение заданного 16-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 16-bit signed integer to an equivalent Boolean value.

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

Параметры

value
Int16 Int16 Int16 Int16

16-разрядное целое число со знаком для преобразования.The 16-bit signed integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Int16 значения Boolean значения.The following example converts an array of Int16 values to Boolean values.

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
Дополнительно

ToBoolean(Decimal) ToBoolean(Decimal) ToBoolean(Decimal) ToBoolean(Decimal)

Преобразует значение заданного десятичного числа в эквивалентное логическое значение.Converts the value of the specified decimal number to an equivalent Boolean value.

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

Параметры

value
Decimal Decimal Decimal Decimal

Преобразуемое число.The number to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Decimal значения Boolean значения.The following example converts an array of Decimal values to Boolean values.

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
Дополнительно

ToBoolean(DateTime) ToBoolean(DateTime) ToBoolean(DateTime) ToBoolean(DateTime)

При вызове этого метода всегда возникает исключение InvalidCastException.Calling this method always throws InvalidCastException.

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

Параметры

value
DateTime DateTime DateTime DateTime

Значение даты и времени для преобразования.The date and time value to convert.

Возвраты

Данное преобразование не поддерживается.This conversion is not supported. Возвращаемое значение отсутствует.No value is returned.

Исключения

Данное преобразование не поддерживается.This conversion is not supported.

Примеры

В следующем примере показано, что попытка преобразовать DateTime выдает значение к логическому типу InvalidCastException.The following example demonstrates that an attempt to convert a DateTime value to a Boolean type throws InvalidCastException.

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) ToBoolean(Char) ToBoolean(Char) ToBoolean(Char)

При вызове этого метода всегда возникает исключение InvalidCastException.Calling this method always throws InvalidCastException.

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

Параметры

value
Char Char Char Char

Знак Юникода, который необходимо преобразовать.The Unicode character to convert.

Возвраты

Данное преобразование не поддерживается.This conversion is not supported. Возвращаемое значение отсутствует.No value is returned.

Исключения

Данное преобразование не поддерживается.This conversion is not supported.

Дополнительно

ToBoolean(Byte) ToBoolean(Byte) ToBoolean(Byte) ToBoolean(Byte)

Преобразует значение заданного 8-битового целого числа без знака в эквивалентное логическое значение.Converts the value of the specified 8-bit unsigned integer to an equivalent Boolean value.

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

Параметры

value
Byte Byte Byte Byte

8-разрядное целое число без знака для преобразования.The 8-bit unsigned integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Byte значения Boolean значения.The following example converts an array of Byte values to Boolean values.

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
Дополнительно

ToBoolean(Boolean) ToBoolean(Boolean) ToBoolean(Boolean) ToBoolean(Boolean)

Возвращает заданное логическое значение; фактическое преобразование не производится.Returns the specified Boolean value; no actual conversion is performed.

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

Параметры

value
Boolean Boolean Boolean Boolean

Возвращаемое логическое значение.The Boolean value to return.

Возвраты

value возвращается без изменений.value is returned unchanged.

Дополнительно

ToBoolean(Int64) ToBoolean(Int64) ToBoolean(Int64) ToBoolean(Int64)

Преобразует значение заданного 64-битового целого числа со знаком в эквивалентное логическое значение.Converts the value of the specified 64-bit signed integer to an equivalent Boolean value.

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

Параметры

value
Int64 Int64 Int64 Int64

64-разрядное целое число со знаком для преобразования.The 64-bit signed integer to convert.

Возвраты

true, если значение параметра value не равно нулю; в противном случае — false.true if value is not zero; otherwise, false.

Примеры

В следующем примере преобразуется в массив Int64 значения Boolean значения.The following example converts an array of Int64 values to Boolean values.

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
Дополнительно

Применяется к