Convert.ToBoolean メソッド (UInt16)
アセンブリ: mscorlib (mscorlib.dll 内)

<CLSCompliantAttribute(False)> _ Public Shared Function ToBoolean ( _ value As UShort _ ) As Boolean
Dim value As UShort Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。


Convert.ToBoolean メソッド (Char)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Char Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
この変換はサポートされていません。値は返されません。



Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。


Convert.ToBoolean メソッド (Int32)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Integer Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。


Convert.ToBoolean メソッド
Convert.ToBoolean メソッド (Object, IFormatProvider)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Object Dim provider As IFormatProvider Dim returnValue As Boolean returnValue = Convert.ToBoolean(value, provider)
戻り値
value が null 参照 (Visual Basic では Nothing) に等しい場合は false。 または true または false。これは、基になる型の value に対して ToBoolean メソッドを実行した結果を示します。


provider を使用すると、value の内容について、カルチャに固有の変換情報を指定できます。たとえば、value が数値を表す String の場合、provider によって、その数値の表記方法に関するカルチャに固有の情報を提供できます。
基本型では provider は無視されますが、value が IConvertible インターフェイスを実装するユーザー定義型の場合は有効となります。

IConvertible を実装するクラスと IFormatProvider を実装するクラスを定義するコード例を次に示します。IConvertible を実装するクラスのオブジェクトは、Double 値の配列を保持します。各クラスのオブジェクトは ToBoolean メソッドに渡されます。このメソッドは、破棄されない配列値のいずれも 0 以外である場合に true を返します。IFormatProvider オブジェクトは、この計算で要素を破棄する方法を決定します。
' Example of the Convert.ToXXX( Object, IFormatProvider ) methods. Imports System Imports System.Collections Imports Microsoft.VisualBasic 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.ToXXX( 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.ToXXX( 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
// Example of the Convert.ToXXX( object, IFormatProvider ) methods. 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.ToXXX( 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.ToXXX( 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 */
// Example of the Convert::ToXXX( Object*, IFormatProvider* ) methods. using namespace System; using namespace System::Collections; // Define the types of averaging available in the class // implementing IConvertible. 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::ToXXX( 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::ToXXX( 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 */
// Example of the Convert.ToXXX( object, IFormatProvider ) methods. import System.* ; import System.Collections.* ; // Define the types of averaging available in the class // implementing IConvertible. public class AverageType { public static final short None = 0; public static final short GeometricMean = 1; public static final short ArithmeticMean = 2; public static final short Median = 3; } //AverageType // 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 int avgType; // Specify the type of averaging in the constructor. public AverageInfo(int avgType) { this.avgType = avgType; } //AverageInfo // This method returns a reference to the containing object // if an object of AverageInfo type is requested. public Object GetFormat(Type argType) { if ( argType == AverageInfo.class.ToType()) { return this ; } else { return null ; } } //GetFormat // Use this property to set or get the type of averaging. /** @property */ public int get_TypeOfAverage() { return this.avgType ; } //get_TypeOfAverage /** @property */ public void set_TypeOfAverage(int value ) { this.avgType = value; } //set_TypeOfAverage } //AverageInfo // 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 ArrayList data; protected AverageInfo defaultProvider; // Construct the object and add an initial list of values. // Create a default format provider. public DataSet(double values[]) { data = new ArrayList(values); defaultProvider = new AverageInfo(AverageType.ArithmeticMean); } //DataSet // Add additional values with this method. public int Add(double value) { data.Add(new Double(value)); return data.get_Count() ; } //Add // Get, set, and add values with this indexer property. /** @property */ public double get_Item(int index) throws InvalidOperationException { if ((index >= 0) && (index < data.get_Count())) { return Convert.ToDouble((data.get_Item(index))) ; } else { throw new InvalidOperationException( "[DataSet.get] Index out of range.") ; } } //get_Item /** @property */ public void set_Item(int index, double value) throws InvalidOperationException { if ((index >= 0) && (index < data.get_Count())) { data.set_Item( index ,(Int64) value ); } else { if ( index == data.get_Count() ) { data.Add((Int64)value); } else { throw new InvalidOperationException( "[DataSet.set] Index out of range.") ; } } } //set_Item // This property returns the number of elements in the object. /** @property */ public int get_Count() { return data.get_Count() ; } //get_Count // This method calculates the average of the object's elements. protected double Average(int avgType) { double SumProd; if ( data.get_Count() == 0 ) { return 0.0 ; } if (avgType == AverageType.GeometricMean) { SumProd = 1.0; for(int index =0 ; index < data.get_Count(); index++) { SumProd = SumProd * Convert.ToDouble((data.get_Item(index))); } // This calculation will not fail with negative // elements. return System.Math.Sign(SumProd) * System.Math.Pow(System.Math.Abs(SumProd), 1.0 / data.get_Count()); } else if (avgType == AverageType.ArithmeticMean ) { SumProd = 0.0; for(int Index=0; Index < data.get_Count(); Index++) { SumProd += Convert.ToDouble((data.get_Item(Index))); } return SumProd / data.get_Count() ; } else if (avgType == AverageType.Median ) { if ( (data.get_Count() % 2) == 0 ) { return ((Convert.ToDouble(data.get_Item(data.get_Count() / 2)) + Convert.ToDouble(data.get_Item(data.get_Count() / 2 - 1))) / 2.0); } else { return Convert.ToDouble(((data.get_Item((data.get_Count() / 2))))) ; } } else { return 0.0 ; } } //Average // 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( AverageInfo.class.ToType()))); } if ( avgInfo == null ) { return defaultProvider ; } else { return avgInfo ; } } //GetAverageInfo // 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.get_TypeOfAverage()); // Limit the range, based on the minimum and maximum values // for the type. return(avg > max) ? max :(avg < min) ? min : avg ; } //CalcNLimitAverage // 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 ; } //GetTypeCode public boolean ToBoolean(IFormatProvider provider) { // ToBoolean is false if the dataset is empty. if ( data.get_Count() <= 0 ) { return false ; } // For median averaging, ToBoolean is true if any // non-discarded elements are nonzero. else { if ( AverageType.Median == GetAverageInfo( provider).get_TypeOfAverage() ) { if ( (data.get_Count() % 2) == 0 ) { return Convert.ToDouble(data.get_Item((data.get_Count() / 2))) != 0.0 || Convert.ToDouble(data.get_Item( (data.get_Count() / 2 - 1))) != 0.0; } else { return Convert.ToDouble(data.get_Item((data.get_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.get_Count(); index++) { if (Convert.ToDouble(data.get_Item(index)) != 0.0) { return true ; } } return false ; } } } //ToBoolean public ubyte ToByte(IFormatProvider provider) { return Convert.ToByte(CalcNLimitAverage(0, 255, provider)); } //ToByte public char ToChar(IFormatProvider provider) { return Convert.ToChar(Convert.ToUInt16(CalcNLimitAverage(Char.MinValue , Char.MaxValue, provider))) ; } //ToChar // 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).get_TypeOfAverage()); try { return DateTime.get_Now().AddSeconds(seconds) ; } catch(ArgumentOutOfRangeException exp) { return(seconds < 0.0) ? DateTime.MinValue : DateTime.MaxValue ; } } //ToDateTime public System.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(-7.92281625142643E+28, 7.92281625142643E+28, provider)) ; } //ToDecimal public double ToDouble(IFormatProvider provider) { return Average(GetAverageInfo(provider).get_TypeOfAverage()) ; } //ToDouble public short ToInt16(IFormatProvider provider) { return Convert.ToInt16(CalcNLimitAverage(Int16.MinValue, Int16.MaxValue, provider)) ; } //ToInt16 public int ToInt32(IFormatProvider provider) { return Convert.ToInt32(CalcNLimitAverage(Int32.MinValue, Int32.MaxValue, provider)) ; } //ToInt32 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(-9223372036854775000L, 9223372036854775000L, provider)) ; } //ToInt64 public byte ToSByte(IFormatProvider provider) { return Convert.ToSByte(CalcNLimitAverage(SByte.MinValue, SByte.MaxValue, provider)) ; } //ToSByte public float ToSingle(IFormatProvider provider) { return Convert.ToSingle(CalcNLimitAverage(Single.MinValue, Single.MaxValue, provider)) ; } //ToSingle public UInt16 ToUInt16(IFormatProvider provider) { return Convert.ToUInt16(CalcNLimitAverage( Convert.ToDouble(UInt16.MinValue), Convert.ToDouble(UInt16.MaxValue), provider)); } //ToUInt16 public UInt32 ToUInt32(IFormatProvider provider) { return Convert.ToUInt32(CalcNLimitAverage( Convert.ToDouble(UInt32.MinValue), Convert.ToDouble(UInt32.MaxValue), provider)) ; } //ToUInt32 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, 1.84467440737095E+19, provider)) ; } //ToUInt64 public Object ToType(Type conversionType, IFormatProvider provider) { return Convert.ChangeType((System.Double)Average( GetAverageInfo(provider).get_TypeOfAverage()), conversionType) ; } //ToType public String ToString(IFormatProvider provider) { int avgType = GetAverageInfo(provider).get_TypeOfAverage(); return String.Format("( {0}: {1} )", (Int32)avgType, ((System.Double)Average(avgType)).ToString("G10")); } //ToString } //DataSet class IConvertibleProviderDemo { // Display a DataSet with three different format providers. public static void DisplayDataSet(DataSet ds) throws InvalidOperationException { 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.get_Count() > 0 ) { Console.Write("\nDataSet: [{0}", (System.Double)ds.get_Item( 0)); for(int iX=1; iX < ds.get_Count(); iX++) { Console.Write(", {0}",(System.Double) ds.get_Item( iX)); } Console.WriteLine("]\n"); } Console.WriteLine(fmt, new Object[] { "Convert.", "Default", "Geometric Mean", "Median" }); Console.WriteLine(fmt, new Object[] { "--------", "-------", "--------------", "------" }); Console.WriteLine(fmt, new Object[] { "ToBoolean", (System.Boolean)Convert.ToBoolean(ds, null), (System.Boolean)Convert.ToBoolean(ds, geMean), (System.Boolean)Convert.ToBoolean(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToByte", (Convert.ToString(Convert.ToByte(ds, null))), (Convert.ToString(Convert.ToByte(ds, geMean))), (Convert.ToString(Convert.ToByte(ds, median))) }); Console.WriteLine(fmt, new Object[] { "ToChar", (Char)Convert.ToChar(ds, null), (Char)Convert.ToChar(ds, geMean), (Char)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}", new Object[] { "ToDateTime", Convert.ToDateTime(ds, null), Convert.ToDateTime(ds, geMean), Convert.ToDateTime(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToDecimal", Convert.ToDecimal(ds, null), Convert.ToDecimal(ds, geMean), Convert.ToDecimal(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToDouble", (System.Double)Convert.ToDouble(ds, null), (System.Double)Convert.ToDouble(ds, geMean), (System.Double)Convert.ToDouble(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToInt16", (System.Int16)Convert.ToInt16(ds, null), (System.Int16)Convert.ToInt16(ds, geMean), (System.Int16)Convert.ToInt16(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToInt32", (System.Int32)Convert.ToInt32(ds, null), (System.Int32)Convert.ToInt32(ds, geMean), (System.Int32)Convert.ToInt32(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToInt64", (System.Int64)Convert.ToInt64(ds, null), (System.Int64)Convert.ToInt64(ds, geMean), (System.Int64)Convert.ToInt64(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToSByte", (System.SByte)Convert.ToSByte(ds, null), (System.SByte)Convert.ToSByte(ds, geMean), (System.SByte)Convert.ToSByte(ds, median) }); Console.WriteLine(fmt, new Object[] { "ToSingle", new Decimal(Convert.ToSingle(ds, null)), new Decimal(Convert.ToSingle(ds, geMean)), new Decimal(Convert.ToSingle(ds, median) )}); Console.WriteLine(fmt, new Object[] { "ToUInt16", Convert.ToUInt16(ds, null), Convert.ToUInt16(ds, geMean), Convert.ToUInt16(ds, median)}); Console.WriteLine(fmt, new Object[] { "ToUInt32", Convert.ToUInt32(ds, null), Convert.ToUInt32(ds, geMean), Convert.ToUInt32(ds, median)}); Console.WriteLine(fmt, new Object[] { "ToUInt64", Convert.ToUInt64(ds, null), Convert.ToUInt64(ds, geMean), Convert.ToUInt64(ds, median)}); } //DisplayDataSet public static void main(String[] args) throws InvalidOperationException { Console.WriteLine(("This example of " + "the Convert.ToXXX( 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(new double[] { 10.5, 22.2, 45.9, 88.7, 156.05, 297.6 }); DisplayDataSet(ds1); DataSet ds2 = new DataSet(new double[] { 359999.95, 425000, 499999.5, 775000, 1695000 }); DisplayDataSet(ds2); } //main } //IConvertibleProviderDemo /* This example of the Convert.ToXXX( 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 */

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Convert.ToBoolean メソッド


Convert.ToBoolean メソッド (Int64)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Long Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (Object)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Object Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が null 参照 (Visual Basic では Nothing) に等しい場合は false。 または true または false。これは、基になる型の value に対して IConvertible.ToBoolean メソッドを実行した結果を示します。

ToBoolean メソッドを使用して、文字列値をブール型に変換する方法を次のコード例に示します。
Public Sub ConvertStringBoolean(ByVal stringVal As String) Dim boolVal As Boolean = False Try boolVal = System.Convert.ToBoolean(stringVal) If boolVal Then System.Console.WriteLine( _ "String is equal to System.Boolean.TrueString.") Else System.Console.WriteLine( _ "String is equal to System.Boolean.FalseString.") End If Catch exception As System.FormatException System.Console.WriteLine( _ "The string must equal System.Boolean.TrueString " + _ "or System.Boolean.FalseString.") End Try ' A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal) System.Console.WriteLine("{0} as a String is {1}", _ boolVal, stringVal) End Sub
public void ConvertStringBoolean(string stringVal) { bool boolVal = false; try { boolVal = System.Convert.ToBoolean(stringVal); if (boolVal) { System.Console.WriteLine( "String was equal to System.Boolean.TrueString."); } else { System.Console.WriteLine( "String was equal to System.Boolean.FalseString."); } } catch (System.FormatException){ System.Console.WriteLine( "The string must equal System.Boolean.TrueString " + "or System.Boolean.FalseString."); } // A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal); System.Console.WriteLine("{0} as a string is {1}" , boolVal, stringVal); }
public: void ConvertStringBoolean( String^ stringVal ) { bool boolVal = false; try { boolVal = System::Convert::ToBoolean( stringVal ); if ( boolVal ) { System::Console::WriteLine( "String was equal to System::Boolean::TrueString." ); } else { System::Console::WriteLine( "String was equal to System::Boolean::FalseString." ); } } catch ( System::FormatException^ ) { System::Console::WriteLine( "The String must equal System::Boolean::TrueString " + "or System::Boolean::FalseString." ); } // A conversion from bool to String will always succeed. stringVal = System::Convert::ToString( boolVal ); System::Console::WriteLine( " {0} as a String is {1}", boolVal, stringVal ); }
public void ConvertStringBoolean(String stringVal) { boolean boolVal = false; try { boolVal = System.Convert.ToBoolean(stringVal); if (boolVal) { System.Console.WriteLine( "String was equal to System.Boolean.TrueString."); } else { System.Console.WriteLine( "String was equal to System.Boolean.FalseString."); } } catch (System.FormatException exp) { System.Console.WriteLine( ("The string must equal System.Boolean.TrueString " + "or System.Boolean.FalseString.")); } // A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal); System.Console.WriteLine("{0} as a string is {1}" , System.Convert.ToString(boolVal), stringVal); } //ConvertStringBoolean

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Convert.ToBoolean メソッド (Byte)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Byte Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (String, IFormatProvider)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As String Dim provider As IFormatProvider Dim returnValue As Boolean returnValue = Convert.ToBoolean(value, provider)
戻り値
value が TrueString に等しい場合は true。value が FalseString または null 参照 (Visual Basic では Nothing) に等しい場合は false。



ToBoolean を使用して String パラメータを受け取る方法については、次のコード例を参照してください。
Public Sub ConvertStringBoolean(ByVal stringVal As String) Dim boolVal As Boolean = False Try boolVal = System.Convert.ToBoolean(stringVal) If boolVal Then System.Console.WriteLine( _ "String is equal to System.Boolean.TrueString.") Else System.Console.WriteLine( _ "String is equal to System.Boolean.FalseString.") End If Catch exception As System.FormatException System.Console.WriteLine( _ "The string must equal System.Boolean.TrueString " + _ "or System.Boolean.FalseString.") End Try ' A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal) System.Console.WriteLine("{0} as a String is {1}", _ boolVal, stringVal) End Sub
public void ConvertStringBoolean(string stringVal) { bool boolVal = false; try { boolVal = System.Convert.ToBoolean(stringVal); if (boolVal) { System.Console.WriteLine( "String was equal to System.Boolean.TrueString."); } else { System.Console.WriteLine( "String was equal to System.Boolean.FalseString."); } } catch (System.FormatException){ System.Console.WriteLine( "The string must equal System.Boolean.TrueString " + "or System.Boolean.FalseString."); } // A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal); System.Console.WriteLine("{0} as a string is {1}" , boolVal, stringVal); }
public: void ConvertStringBoolean( String^ stringVal ) { bool boolVal = false; try { boolVal = System::Convert::ToBoolean( stringVal ); if ( boolVal ) { System::Console::WriteLine( "String was equal to System::Boolean::TrueString." ); } else { System::Console::WriteLine( "String was equal to System::Boolean::FalseString." ); } } catch ( System::FormatException^ ) { System::Console::WriteLine( "The String must equal System::Boolean::TrueString " + "or System::Boolean::FalseString." ); } // A conversion from bool to String will always succeed. stringVal = System::Convert::ToString( boolVal ); System::Console::WriteLine( " {0} as a String is {1}", boolVal, stringVal ); }
public void ConvertStringBoolean(String stringVal) { boolean boolVal = false; try { boolVal = System.Convert.ToBoolean(stringVal); if (boolVal) { System.Console.WriteLine( "String was equal to System.Boolean.TrueString."); } else { System.Console.WriteLine( "String was equal to System.Boolean.FalseString."); } } catch (System.FormatException exp) { System.Console.WriteLine( ("The string must equal System.Boolean.TrueString " + "or System.Boolean.FalseString.")); } // A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal); System.Console.WriteLine("{0} as a string is {1}" , System.Convert.ToString(boolVal), stringVal); } //ConvertStringBoolean

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (SByte)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As SByte Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (Int16)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Short Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (Double)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Double Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

ToBoolean メソッドを使用して、パラメータとして Double を受け取る方法を次のコード例に示します。
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
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 void ConvertDoubleBool(double doubleVal) { boolean boolVal; // Double to bool conversion cannot overflow. boolVal = System.Convert.ToBoolean(doubleVal); System.Console.WriteLine("{0} as a Boolean is: {1}.", System.Convert.ToString(doubleVal), System.Convert.ToString(boolVal)); // bool to double conversion cannot overflow. doubleVal = System.Convert.ToDouble(boolVal); System.Console.WriteLine("{0} as a double is: {1}.", System.Convert.ToString(boolVal), System.Convert.ToString(doubleVal)); } //ConvertDoubleBool

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (UInt64)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As ULong Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (Single)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Single Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (Decimal)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Decimal Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (Boolean)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As Boolean Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
パラメータ value は変更されずに返されます。

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (String)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As String Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が TrueString に等しい場合は true。value が FalseString または null 参照 (Visual Basic では Nothing) に等しい場合は false。


ToBoolean を使用して String パラメータを受け取る方法については、次のコード例を参照してください。
Public Sub ConvertStringBoolean(ByVal stringVal As String) Dim boolVal As Boolean = False Try boolVal = System.Convert.ToBoolean(stringVal) If boolVal Then System.Console.WriteLine( _ "String is equal to System.Boolean.TrueString.") Else System.Console.WriteLine( _ "String is equal to System.Boolean.FalseString.") End If Catch exception As System.FormatException System.Console.WriteLine( _ "The string must equal System.Boolean.TrueString " + _ "or System.Boolean.FalseString.") End Try ' A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal) System.Console.WriteLine("{0} as a String is {1}", _ boolVal, stringVal) End Sub
public void ConvertStringBoolean(string stringVal) { bool boolVal = false; try { boolVal = System.Convert.ToBoolean(stringVal); if (boolVal) { System.Console.WriteLine( "String was equal to System.Boolean.TrueString."); } else { System.Console.WriteLine( "String was equal to System.Boolean.FalseString."); } } catch (System.FormatException){ System.Console.WriteLine( "The string must equal System.Boolean.TrueString " + "or System.Boolean.FalseString."); } // A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal); System.Console.WriteLine("{0} as a string is {1}" , boolVal, stringVal); }
public: void ConvertStringBoolean( String^ stringVal ) { bool boolVal = false; try { boolVal = System::Convert::ToBoolean( stringVal ); if ( boolVal ) { System::Console::WriteLine( "String was equal to System::Boolean::TrueString." ); } else { System::Console::WriteLine( "String was equal to System::Boolean::FalseString." ); } } catch ( System::FormatException^ ) { System::Console::WriteLine( "The String must equal System::Boolean::TrueString " + "or System::Boolean::FalseString." ); } // A conversion from bool to String will always succeed. stringVal = System::Convert::ToString( boolVal ); System::Console::WriteLine( " {0} as a String is {1}", boolVal, stringVal ); }
public void ConvertStringBoolean(String stringVal) { boolean boolVal = false; try { boolVal = System.Convert.ToBoolean(stringVal); if (boolVal) { System.Console.WriteLine( "String was equal to System.Boolean.TrueString."); } else { System.Console.WriteLine( "String was equal to System.Boolean.FalseString."); } } catch (System.FormatException exp) { System.Console.WriteLine( ("The string must equal System.Boolean.TrueString " + "or System.Boolean.FalseString.")); } // A conversion from bool to string will always succeed. stringVal = System.Convert.ToString(boolVal); System.Console.WriteLine("{0} as a string is {1}" , System.Convert.ToString(boolVal), stringVal); } //ConvertStringBoolean

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (UInt32)
アセンブリ: mscorlib (mscorlib.dll 内)

<CLSCompliantAttribute(False)> _ Public Shared Function ToBoolean ( _ value As UInteger _ ) As Boolean
Dim value As UInteger Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
value が 0 以外の場合は true。0 の場合は false。

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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Convert.ToBoolean メソッド (DateTime)
アセンブリ: mscorlib (mscorlib.dll 内)

Dim value As DateTime Dim returnValue As Boolean returnValue = Convert.ToBoolean(value)
戻り値
この変換はサポートされていません。値は返されません。



DateTime 値からブール値へ変換すると InvalidCastException がスローされるコード例を次に示します。
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 framework.") End Try End Sub
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 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( 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 framework." ); } }
public void ConvertBoolean() { final int year = 1979; final int month = 7; final int day = 28; final int hour = 13; final int minute = 26; final int second = 15; final int millisecond = 53; DateTime dateTime = new DateTime(year, month, day, hour, minute, second, millisecond); boolean boolVal; // System.InvalidCastException is always thrown. try { boolVal = System.Convert.ToBoolean(dateTime); } catch (System.InvalidCastException exp) { System.Console.WriteLine(("Conversion from DateTime to " + "Boolean is not supported by the framework.")); } } //ConvertBoolean

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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