Convert.ToBoolean Metódus
Definíció
Fontos
Egyes információk olyan, kiadás előtti termékekre vonatkoznak, amelyek a kiadásig még jelentősen módosulhatnak. A Microsoft nem vállal kifejezett vagy törvényi garanciát az itt megjelenő információért.
Egy megadott értéket egyenértékű logikai értékké alakít át.
Túlterhelések
| Name | Description |
|---|---|
| ToBoolean(SByte) |
A megadott 8 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(String, IFormatProvider) |
A logikai érték megadott sztring-ábrázolását logikai megfelelővé alakítja a megadott kultúraspecifikus formázási információk használatával. |
| ToBoolean(Object, IFormatProvider) |
A megadott objektum értékét egyenértékű logikai értékké alakítja a megadott kultúraspecifikus formázási információk használatával. |
| ToBoolean(UInt64) |
A megadott 64 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(UInt32) |
A megadott 32 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(UInt16) |
A megadott 16 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(String) |
Egy logikai érték megadott sztring-ábrázolását logikai megfelelővé alakítja. |
| ToBoolean(Single) |
A megadott egypontos lebegőpontos szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(Object) |
Egy adott objektum értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(Double) |
A megadott dupla pontosságú lebegőpontos szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(Int32) |
A megadott 32 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(Int16) |
A megadott 16 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(Decimal) |
A megadott decimális szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(DateTime) |
Ennek a metódusnak a meghívása InvalidCastExceptionmindig dob. |
| ToBoolean(Char) |
Ennek a metódusnak a meghívása InvalidCastExceptionmindig dob. |
| ToBoolean(Byte) |
A megadott 8 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja. |
| ToBoolean(Boolean) |
A megadott logikai értéket adja vissza; nincs tényleges átalakítás. |
| ToBoolean(Int64) |
A megadott 64 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja. |
ToBoolean(SByte)
Fontos
Ez az API nem CLS-kompatibilis.
A megadott 8 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::SByte value);[System.CLSCompliant(false)]
public static bool ToBoolean(sbyte value);[<System.CLSCompliant(false)>]
static member ToBoolean : sbyte -> boolPublic Shared Function ToBoolean (value As SByte) As BooleanParaméterek
- value
- SByte
A konvertálandó 8 bites aláírt egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
- Attribútumok
Példák
Az alábbi példa egy értéktömböt SByte konvertál értékké Boolean .
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
let numbers =
[| SByte.MinValue; -1y; 0y
10y; 100y; SByte.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-5} --> {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
Lásd még
A következőre érvényes:
ToBoolean(String, IFormatProvider)
A logikai érték megadott sztring-ábrázolását logikai megfelelővé alakítja a megadott kultúraspecifikus formázási információk használatával.
public:
static bool ToBoolean(System::String ^ value, IFormatProvider ^ provider);public static bool ToBoolean(string value, IFormatProvider provider);static member ToBoolean : string * IFormatProvider -> boolPublic Shared Function ToBoolean (value As String, provider As IFormatProvider) As BooleanParaméterek
- value
- String
Egy sztring, amely a következő értékeket tartalmazza: vagy TrueStringFalseString.
- provider
- IFormatProvider
Egy objektum, amely kultúraspecifikus formázási információkat tartalmaz. Ezt a paramétert a rendszer figyelmen kívül hagyja.
Válaszok
trueha value egyenlő, vagy false egyenlő valueFalseString vagy null.TrueString
Kivételek
value nem egyenlő vagy TrueStringFalseString.
Megjegyzések
Ha inkább nem szeretne kivételt kezelni, ha az átalakítás sikertelen, hívhatja meg helyette a metódust Boolean.TryParse . Egy értéket ad Boolean vissza, amely jelzi, hogy az átalakítás sikeres volt-e vagy nem sikerült.
Lásd még
A következőre érvényes:
ToBoolean(Object, IFormatProvider)
A megadott objektum értékét egyenértékű logikai értékké alakítja a megadott kultúraspecifikus formázási információk használatával.
public:
static bool ToBoolean(System::Object ^ value, IFormatProvider ^ provider);public static bool ToBoolean(object value, IFormatProvider provider);static member ToBoolean : obj * IFormatProvider -> boolPublic Shared Function ToBoolean (value As Object, provider As IFormatProvider) As BooleanParaméterek
- value
- Object
Az interfészt megvalósító IConvertible objektum, vagy null.
- provider
- IFormatProvider
Egy objektum, amely kultúraspecifikus formázási információkat tartalmaz.
Válaszok
truevagy false, amely az alapul szolgáló típus valuemetódusának meghívásával ToBoolean(IFormatProvider) visszaadott értéket tükrözi. Ha value igen null, a metódus visszaadja false.
Kivételek
value olyan sztring, amely nem egyenlő TrueString vagy FalseString.
value nem implementálja az interfészt IConvertible .
-vagy-
A konvertálás valueBoolean nem támogatott.
Példák
Az alábbi példa egy implementálható IConvertible osztályt és egy implementálható osztályt IFormatProviderhatároz meg. A megvalósítandó osztály objektumai IConvertible értéktömböt Double tartalmaznak. Az egyes osztályok objektumai átadva lesznek a ToBoolean(Object, IFormatProvider) metódusnak. Ez a metódus akkor ad true vissza, ha a nem elvetett tömbértékek bármelyike nem nulla. Az IFormatProvider objektum határozza meg, hogy az elemek hogyan lesznek elvetve ehhez a számításhoz.
using System;
using System.Collections;
// Define the types of averaging available in the class
// implementing IConvertible.
public enum AverageType : short
{
None = 0,
GeometricMean = 1,
ArithmeticMean = 2,
Median = 3
};
// Pass an instance of this class to methods that require an
// IFormatProvider. The class instance determines the type of
// average to calculate.
public class AverageInfo : IFormatProvider
{
protected AverageType AvgType;
// Specify the type of averaging in the constructor.
public AverageInfo( AverageType avgType )
{
this.AvgType = avgType;
}
// This method returns a reference to the containing object
// if an object of AverageInfo type is requested.
public object GetFormat( Type argType )
{
if ( argType == typeof( AverageInfo ) )
return this;
else
return null;
}
// Use this property to set or get the type of averaging.
public AverageType TypeOfAverage
{
get { return this.AvgType; }
set { this.AvgType = value; }
}
}
// This class encapsulates an array of double values and implements
// the IConvertible interface. Most of the IConvertible methods
// return an average of the array elements in one of three types:
// arithmetic mean, geometric mean, or median.
public class DataSet : IConvertible
{
protected ArrayList data;
protected AverageInfo defaultProvider;
// Construct the object and add an initial list of values.
// Create a default format provider.
public DataSet( params double[ ] values )
{
data = new ArrayList( values );
defaultProvider =
new AverageInfo( AverageType.ArithmeticMean );
}
// Add additional values with this method.
public int Add( double value )
{
data.Add( value );
return data.Count;
}
// Get, set, and add values with this indexer property.
public double this[ int index ]
{
get
{
if( index >= 0 && index < data.Count )
return (double)data[ index ];
else
throw new InvalidOperationException(
"[DataSet.get] Index out of range." );
}
set
{
if( index >= 0 && index < data.Count )
data[ index ] = value;
else if( index == data.Count )
data.Add( value );
else
throw new InvalidOperationException(
"[DataSet.set] Index out of range." );
}
}
// This property returns the number of elements in the object.
public int Count
{
get { return data.Count; }
}
// This method calculates the average of the object's elements.
protected double Average( AverageType avgType )
{
double SumProd;
if( data.Count == 0 )
return 0.0;
switch( avgType )
{
case AverageType.GeometricMean:
SumProd = 1.0;
for( int Index = 0; Index < data.Count; Index++ )
SumProd *= (double)data[ Index ];
// This calculation will not fail with negative
// elements.
return Math.Sign( SumProd ) * Math.Pow(
Math.Abs( SumProd ), 1.0 / data.Count );
case AverageType.ArithmeticMean:
SumProd = 0.0;
for( int Index = 0; Index < data.Count; Index++ )
SumProd += (double)data[ Index ];
return SumProd / data.Count;
case AverageType.Median:
if( data.Count % 2 == 0 )
return ( (double)data[ data.Count / 2 ] +
(double)data[ data.Count / 2 - 1 ] ) / 2.0;
else
return (double)data[ data.Count / 2 ];
default:
return 0.0;
}
}
// Get the AverageInfo object from the caller's format provider,
// or use the local default.
protected AverageInfo GetAverageInfo( IFormatProvider provider )
{
AverageInfo avgInfo = null;
if( provider != null )
avgInfo = (AverageInfo)provider.GetFormat(
typeof( AverageInfo ) );
if ( avgInfo == null )
return defaultProvider;
else
return avgInfo;
}
// Calculate the average and limit the range.
protected double CalcNLimitAverage( double min, double max,
IFormatProvider provider )
{
// Get the format provider and calculate the average.
AverageInfo avgInfo = GetAverageInfo( provider );
double avg = Average( avgInfo.TypeOfAverage );
// Limit the range, based on the minimum and maximum values
// for the type.
return avg > max ? max : avg < min ? min : avg;
}
// The following elements are required by IConvertible.
// None of these conversion functions throw exceptions. When
// the data is out of range for the type, the appropriate
// MinValue or MaxValue is used.
public TypeCode GetTypeCode( )
{
return TypeCode.Object;
}
public bool ToBoolean( IFormatProvider provider )
{
// ToBoolean is false if the dataset is empty.
if( data.Count <= 0 )
{
return false;
}
// For median averaging, ToBoolean is true if any
// non-discarded elements are nonzero.
else if( AverageType.Median ==
GetAverageInfo( provider ).TypeOfAverage )
{
if (data.Count % 2 == 0 )
return ( (double)data[ data.Count / 2 ] != 0.0 ||
(double)data[ data.Count / 2 - 1 ] != 0.0 );
else
return (double)data[ data.Count / 2 ] != 0.0;
}
// For arithmetic or geometric mean averaging, ToBoolean is
// true if any element of the dataset is nonzero.
else
{
for( int Index = 0; Index < data.Count; Index++ )
if( (double)data[ Index ] != 0.0 )
return true;
return false;
}
}
public byte ToByte( IFormatProvider provider )
{
return Convert.ToByte( CalcNLimitAverage(
Byte.MinValue, Byte.MaxValue, provider ) );
}
public char ToChar( IFormatProvider provider )
{
return Convert.ToChar( Convert.ToUInt16( CalcNLimitAverage(
Char.MinValue, Char.MaxValue, provider ) ) );
}
// Convert to DateTime by adding the calculated average as
// seconds to the current date and time. A valid DateTime is
// always returned.
public DateTime ToDateTime( IFormatProvider provider )
{
double seconds =
Average( GetAverageInfo( provider ).TypeOfAverage );
try
{
return DateTime.Now.AddSeconds( seconds );
}
catch( ArgumentOutOfRangeException )
{
return seconds < 0.0 ? DateTime.MinValue : DateTime.MaxValue;
}
}
public decimal ToDecimal( IFormatProvider provider )
{
// The Double conversion rounds Decimal.MinValue and
// Decimal.MaxValue to invalid Decimal values, so the
// following limits must be used.
return Convert.ToDecimal( CalcNLimitAverage(
-79228162514264330000000000000.0,
79228162514264330000000000000.0, provider ) );
}
public double ToDouble( IFormatProvider provider )
{
return Average( GetAverageInfo(provider).TypeOfAverage );
}
public short ToInt16( IFormatProvider provider )
{
return Convert.ToInt16( CalcNLimitAverage(
Int16.MinValue, Int16.MaxValue, provider ) );
}
public int ToInt32( IFormatProvider provider )
{
return Convert.ToInt32( CalcNLimitAverage(
Int32.MinValue, Int32.MaxValue, provider ) );
}
public long ToInt64( IFormatProvider provider )
{
// The Double conversion rounds Int64.MinValue and
// Int64.MaxValue to invalid Int64 values, so the following
// limits must be used.
return Convert.ToInt64( CalcNLimitAverage(
-9223372036854775000, 9223372036854775000, provider ) );
}
public SByte ToSByte( IFormatProvider provider )
{
return Convert.ToSByte( CalcNLimitAverage(
SByte.MinValue, SByte.MaxValue, provider ) );
}
public float ToSingle( IFormatProvider provider )
{
return Convert.ToSingle( CalcNLimitAverage(
Single.MinValue, Single.MaxValue, provider ) );
}
public UInt16 ToUInt16( IFormatProvider provider )
{
return Convert.ToUInt16( CalcNLimitAverage(
UInt16.MinValue, UInt16.MaxValue, provider ) );
}
public UInt32 ToUInt32( IFormatProvider provider )
{
return Convert.ToUInt32( CalcNLimitAverage(
UInt32.MinValue, UInt32.MaxValue, provider ) );
}
public UInt64 ToUInt64( IFormatProvider provider )
{
// The Double conversion rounds UInt64.MaxValue to an invalid
// UInt64 value, so the following limit must be used.
return Convert.ToUInt64( CalcNLimitAverage(
0, 18446744073709550000.0, provider ) );
}
public object ToType( Type conversionType,
IFormatProvider provider )
{
return Convert.ChangeType( Average(
GetAverageInfo( provider ).TypeOfAverage ),
conversionType );
}
public string ToString( IFormatProvider provider )
{
AverageType avgType = GetAverageInfo( provider ).TypeOfAverage;
return String.Format( "( {0}: {1:G10} )", avgType,
Average( avgType ) );
}
}
class IConvertibleProviderDemo
{
// Display a DataSet with three different format providers.
public static void DisplayDataSet( DataSet ds )
{
string fmt = "{0,-12}{1,20}{2,20}{3,20}";
AverageInfo median = new AverageInfo( AverageType.Median );
AverageInfo geMean =
new AverageInfo( AverageType.GeometricMean );
// Display the dataset elements.
if( ds.Count > 0 )
{
Console.Write( "\nDataSet: [{0}", ds[ 0 ] );
for( int iX = 1; iX < ds.Count; iX++ )
Console.Write( ", {0}", ds[ iX ] );
Console.WriteLine( "]\n" );
}
Console.WriteLine( fmt, "Convert.", "Default",
"Geometric Mean", "Median");
Console.WriteLine( fmt, "--------", "-------",
"--------------", "------");
Console.WriteLine( fmt, "ToBoolean",
Convert.ToBoolean( ds, null ),
Convert.ToBoolean( ds, geMean ),
Convert.ToBoolean( ds, median ) );
Console.WriteLine( fmt, "ToByte",
Convert.ToByte( ds, null ),
Convert.ToByte( ds, geMean ),
Convert.ToByte( ds, median ) );
Console.WriteLine( fmt, "ToChar",
Convert.ToChar( ds, null ),
Convert.ToChar( ds, geMean ),
Convert.ToChar( ds, median ) );
Console.WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}" +
"{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}",
"ToDateTime", Convert.ToDateTime( ds, null ),
Convert.ToDateTime( ds, geMean ),
Convert.ToDateTime( ds, median ) );
Console.WriteLine( fmt, "ToDecimal",
Convert.ToDecimal( ds, null ),
Convert.ToDecimal( ds, geMean ),
Convert.ToDecimal( ds, median ) );
Console.WriteLine( fmt, "ToDouble",
Convert.ToDouble( ds, null ),
Convert.ToDouble( ds, geMean ),
Convert.ToDouble( ds, median ) );
Console.WriteLine( fmt, "ToInt16",
Convert.ToInt16( ds, null ),
Convert.ToInt16( ds, geMean ),
Convert.ToInt16( ds, median ) );
Console.WriteLine( fmt, "ToInt32",
Convert.ToInt32( ds, null ),
Convert.ToInt32( ds, geMean ),
Convert.ToInt32( ds, median ) );
Console.WriteLine( fmt, "ToInt64",
Convert.ToInt64( ds, null ),
Convert.ToInt64( ds, geMean ),
Convert.ToInt64( ds, median ) );
Console.WriteLine( fmt, "ToSByte",
Convert.ToSByte( ds, null ),
Convert.ToSByte( ds, geMean ),
Convert.ToSByte( ds, median ) );
Console.WriteLine( fmt, "ToSingle",
Convert.ToSingle( ds, null ),
Convert.ToSingle( ds, geMean ),
Convert.ToSingle( ds, median ) );
Console.WriteLine( fmt, "ToUInt16",
Convert.ToUInt16( ds, null ),
Convert.ToUInt16( ds, geMean ),
Convert.ToUInt16( ds, median ) );
Console.WriteLine( fmt, "ToUInt32",
Convert.ToUInt32( ds, null ),
Convert.ToUInt32( ds, geMean ),
Convert.ToUInt32( ds, median ) );
Console.WriteLine( fmt, "ToUInt64",
Convert.ToUInt64( ds, null ),
Convert.ToUInt64( ds, geMean ),
Convert.ToUInt64( ds, median ) );
}
public static void Main( )
{
Console.WriteLine( "This example of " +
"the Convert.To<Type>( object, IFormatProvider ) methods " +
"\ngenerates the following output. The example " +
"displays the values \nreturned by the methods, " +
"using several IFormatProvider objects.\n" );
DataSet ds1 = new DataSet(
10.5, 22.2, 45.9, 88.7, 156.05, 297.6 );
DisplayDataSet( ds1 );
DataSet ds2 = new DataSet(
359999.95, 425000, 499999.5, 775000, 1695000 );
DisplayDataSet( ds2 );
}
}
/*
This example of the Convert.To<Type>( object, IFormatProvider ) methods
generates the following output. The example displays the values
returned by the methods, using several IFormatProvider objects.
DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
Convert. Default Geometric Mean Median
-------- ------- -------------- ------
ToBoolean True True True
ToByte 103 59 67
ToChar g ; C
ToDateTime 2003-05-13 15:04:12 2003-05-13 15:03:28 2003-05-13 15:03:35
ToDecimal 103.491666666667 59.4332135445164 67.3
ToDouble 103.491666666667 59.4332135445164 67.3
ToInt16 103 59 67
ToInt32 103 59 67
ToInt64 103 59 67
ToSByte 103 59 67
ToSingle 103.4917 59.43321 67.3
ToUInt16 103 59 67
ToUInt32 103 59 67
ToUInt64 103 59 67
DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
Convert. Default Geometric Mean Median
-------- ------- -------------- ------
ToBoolean True True True
ToByte 255 255 255
ToChar ? ? ?
ToDateTime 2003-05-22 07:39:08 2003-05-20 22:28:45 2003-05-19 09:55:48
ToDecimal 750999.89 631577.237188435 499999.5
ToDouble 750999.89 631577.237188435 499999.5
ToInt16 32767 32767 32767
ToInt32 751000 631577 500000
ToInt64 751000 631577 500000
ToSByte 127 127 127
ToSingle 750999.9 631577.3 499999.5
ToUInt16 65535 65535 65535
ToUInt32 751000 631577 500000
ToUInt64 751000 631577 500000
*/
open System
open System.Collections
// Define the types of averaging available in the class
// implementing IConvertible.
type AverageType =
| None = 0s
| GeometricMean = 1s
| ArithmeticMean = 2s
| Median = 3s
// Pass an instance of this class to methods that require an
// IFormatProvider. The class instance determines the type of
// average to calculate.
[<AllowNullLiteral>]
type AverageInfo(avgType: AverageType) =
// Use this property to set or get the type of averaging.
member val TypeOfAverage = avgType with get, set
interface IFormatProvider with
// This method returns a reference to the containing object
// if an object of AverageInfo type is requested.
member this.GetFormat(argType: Type) =
if argType = typeof<AverageInfo> then
this
else
null
// This class encapsulates an array of double values and implements
// the IConvertible interface. Most of the IConvertible methods
// an average of the array elements in one of three types:
// arithmetic mean, geometric mean, or median.
type DataSet([<ParamArray>] values: double[]) =
let data = ResizeArray values
let defaultProvider =
AverageInfo AverageType.ArithmeticMean
// Add additional values with this method.
member _.Add(value: double) =
data.Add value
data.Count
// Get, set, and add values with this indexer property.
member _.Item
with get (index) =
if index >= 0 && index < data.Count then
data[index]
else
raise (InvalidOperationException "[DataSet.get] Index out of range.")
and set index value =
if index >= 0 && index < data.Count then
data[index] <- value
elif index = data.Count then
data.Add value
else
raise (InvalidOperationException "[DataSet.set] Index out of range.")
// This property returns the number of elements in the object.
member _.Count =
data.Count
// This method calculates the average of the object's elements.
member _.Average(avgType: AverageType) =
if data.Count = 0 then
0.0
else
match avgType with
| AverageType.GeometricMean ->
let sumProd =
Seq.reduce ( * ) data
// This calculation will not fail with negative
// elements.
(sign sumProd |> float) * Math.Pow(abs sumProd, 1.0 / (float data.Count))
| AverageType.ArithmeticMean ->
Seq.average data
| AverageType.Median ->
if data.Count % 2 = 0 then
(data[data.Count / 2] + data[data.Count / 2 - 1]) / 2.0
else
data[ data.Count / 2]
| _ ->
0.0
// Get the AverageInfo object from the caller's format provider,
// or use the local default.
member _.GetAverageInfo(provider: IFormatProvider) =
let avgInfo =
if provider <> null then
provider.GetFormat typeof<AverageInfo> :?> AverageInfo
else
null
if avgInfo = null then
defaultProvider
else
avgInfo
// Calculate the average and limit the range.
member this.CalcNLimitAverage(min: double, max: double, provider: IFormatProvider) =
// Get the format provider and calculate the average.
let avgInfo = this.GetAverageInfo provider
let avg = this.Average avgInfo.TypeOfAverage
// Limit the range, based on the minimum and maximum values
// for the type.
if avg > max then max elif avg < min then min else avg
// The following elements are required by IConvertible.
interface IConvertible with
// None of these conversion functions throw exceptions. When
// the data is out of range for the type, the appropriate
// MinValue or MaxValue is used.
member _.GetTypeCode() =
TypeCode.Object
member this.ToBoolean(provider: IFormatProvider) =
// ToBoolean is false if the dataset is empty.
if data.Count <= 0 then
false
// For median averaging, ToBoolean is true if any
// non-discarded elements are nonzero.
elif AverageType.Median = this.GetAverageInfo(provider).TypeOfAverage then
if data.Count % 2 = 0 then
(data[data.Count / 2] <> 0.0 || data[data.Count / 2 - 1] <> 0.0)
else
data[data.Count / 2] <> 0.0
// For arithmetic or geometric mean averaging, ToBoolean is
// true if any element of the dataset is nonzero.
else
Seq.exists (fun x -> x <> 0.0) data
member this.ToByte(provider: IFormatProvider) =
Convert.ToByte(this.CalcNLimitAverage(float Byte.MinValue, float Byte.MaxValue, provider) )
member this.ToChar(provider: IFormatProvider) =
Convert.ToChar(Convert.ToUInt16(this.CalcNLimitAverage(float Char.MinValue, float Char.MaxValue, provider) ) )
// Convert to DateTime by adding the calculated average as
// seconds to the current date and time. A valid DateTime is
// always returned.
member this.ToDateTime(provider: IFormatProvider) =
let seconds = this.Average(this.GetAverageInfo(provider).TypeOfAverage)
try
DateTime.Now.AddSeconds seconds
with :? ArgumentOutOfRangeException ->
if seconds < 0.0 then DateTime.MinValue else DateTime.MaxValue
member this.ToDecimal(provider: IFormatProvider) =
// The Double conversion rounds Decimal.MinValue and
// Decimal.MaxValue to invalid Decimal values, so the
// following limits must be used.
Convert.ToDecimal(this.CalcNLimitAverage(-79228162514264330000000000000.0, 79228162514264330000000000000.0, provider) )
member this.ToDouble(provider: IFormatProvider) =
this.Average(this.GetAverageInfo(provider).TypeOfAverage)
member this.ToInt16(provider: IFormatProvider) =
Convert.ToInt16(this.CalcNLimitAverage(float Int16.MinValue, float Int16.MaxValue, provider) )
member this.ToInt32(provider: IFormatProvider) =
Convert.ToInt32(this.CalcNLimitAverage(Int32.MinValue, Int32.MaxValue, provider) )
member this.ToInt64(provider: IFormatProvider) =
// The Double conversion rounds Int64.MinValue and
// Int64.MaxValue to invalid Int64 values, so the following
// limits must be used.
Convert.ToInt64(this.CalcNLimitAverage(-9223372036854775000., 9223372036854775000., provider) )
member this.ToSByte(provider: IFormatProvider) =
Convert.ToSByte(this.CalcNLimitAverage(float SByte.MinValue, float SByte.MaxValue, provider) )
member this.ToSingle(provider: IFormatProvider) =
Convert.ToSingle(this.CalcNLimitAverage(float Single.MinValue, float Single.MaxValue, provider) )
member this.ToUInt16(provider: IFormatProvider) =
Convert.ToUInt16(this.CalcNLimitAverage(float UInt16.MinValue, float UInt16.MaxValue, provider) )
member this.ToUInt32(provider: IFormatProvider) =
Convert.ToUInt32(this.CalcNLimitAverage(float UInt32.MinValue, float UInt32.MaxValue, provider) )
member this.ToUInt64(provider: IFormatProvider) =
// The Double conversion rounds UInt64.MaxValue to an invalid
// UInt64 value, so the following limit must be used.
Convert.ToUInt64(this.CalcNLimitAverage(0, 18446744073709550000.0, provider) )
member this.ToType(conversionType: Type, provider: IFormatProvider) =
Convert.ChangeType(this.Average(this.GetAverageInfo(provider).TypeOfAverage), conversionType)
member this.ToString(provider: IFormatProvider) =
let avgType = this.GetAverageInfo(provider).TypeOfAverage
$"( {avgType}: {this.Average avgType:G10} )"
// Display a DataSet with three different format providers.
let displayDataSet (ds: DataSet) =
let fmt obj1 obj2 obj3 obj4 = printfn $"{obj1,-12}{obj2,20}{obj3,20}{obj4,20}"
let median = AverageInfo AverageType.Median
let geMean =
AverageInfo AverageType.GeometricMean
// Display the dataset elements.
if ds.Count > 0 then
printf $"\nDataSet: [{ds[0]}"
for i = 1 to ds.Count - 1 do
printf $", {ds[i]}"
printfn "]\n"
fmt "Convert." "Default" "Geometric Mean" "Median"
fmt "--------" "-------" "--------------" "------"
fmt "ToBoolean"
(Convert.ToBoolean(ds, null))
(Convert.ToBoolean(ds, geMean))
(Convert.ToBoolean(ds, median))
fmt "ToByte"
(Convert.ToByte(ds, null))
(Convert.ToByte(ds, geMean))
(Convert.ToByte(ds, median))
fmt "ToChar"
(Convert.ToChar(ds, null))
(Convert.ToChar(ds, geMean))
(Convert.ToChar(ds, median))
printfn $"""{"ToDateTime",-12}{Convert.ToDateTime(ds, null).ToString "20:yyyy-MM-dd HH:mm:ss"}{Convert.ToDateTime(ds, geMean).ToString "20:yyyy-MM-dd HH:mm:ss"}{Convert.ToDateTime(ds, median).ToString "20:yyyy-MM-dd HH:mm:ss"}"""
fmt "ToDecimal"
(Convert.ToDecimal(ds, null))
(Convert.ToDecimal(ds, geMean))
(Convert.ToDecimal(ds, median))
fmt "ToDouble"
(Convert.ToDouble(ds, null))
(Convert.ToDouble(ds, geMean))
(Convert.ToDouble(ds, median))
fmt "ToInt16"
(Convert.ToInt16(ds, null))
(Convert.ToInt16(ds, geMean))
(Convert.ToInt16(ds, median))
fmt "ToInt32"
(Convert.ToInt32(ds, null))
(Convert.ToInt32(ds, geMean))
(Convert.ToInt32(ds, median))
fmt "ToInt64"
(Convert.ToInt64(ds, null))
(Convert.ToInt64(ds, geMean))
(Convert.ToInt64(ds, median))
fmt "ToSByte"
(Convert.ToSByte(ds, null))
(Convert.ToSByte(ds, geMean))
(Convert.ToSByte(ds, median))
fmt "ToSingle"
(Convert.ToSingle(ds, null))
(Convert.ToSingle(ds, geMean))
(Convert.ToSingle(ds, median))
fmt "ToUInt16"
(Convert.ToUInt16(ds, null))
(Convert.ToUInt16(ds, geMean))
(Convert.ToUInt16(ds, median))
fmt "ToUInt32"
(Convert.ToUInt32(ds, null))
(Convert.ToUInt32(ds, geMean))
(Convert.ToUInt32(ds, median))
fmt "ToUInt64"
(Convert.ToUInt64(ds, null))
(Convert.ToUInt64(ds, geMean))
(Convert.ToUInt64(ds, median))
printfn
"""This example of the Convert.To<Type>( object, IFormatprovider) methods
generates the following output. The example displays the values
returned by the methods, using several IFormatProvider objects.
"""
let ds1 = DataSet(10.5, 22.2, 45.9, 88.7, 156.05, 297.6)
displayDataSet ds1
let ds2 = DataSet(359999.95, 425000, 499999.5, 775000, 1695000)
displayDataSet ds2
// This example of the Convert.To<Type>( object, IFormatprovider) methods
// generates the following output. The example displays the values
// returned by the methods, using several IFormatProvider objects.
//
// DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
//
// Convert. Default Geometric Mean Median
// -------- ------- -------------- ------
// ToBoolean True True True
// ToByte 103 59 67
// ToChar g ; C
// ToDateTime 2003-05-13 15:04:12 2003-05-13 15:03:28 2003-05-13 15:03:35
// ToDecimal 103.491666666667 59.4332135445164 67.3
// ToDouble 103.491666666667 59.4332135445164 67.3
// ToInt16 103 59 67
// ToInt32 103 59 67
// ToInt64 103 59 67
// ToSByte 103 59 67
// ToSingle 103.4917 59.43321 67.3
// ToUInt16 103 59 67
// ToUInt32 103 59 67
// ToUInt64 103 59 67
//
// DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
//
// Convert. Default Geometric Mean Median
// -------- ------- -------------- ------
// ToBoolean True True True
// ToByte 255 255 255
// ToChar ? ? ?
// ToDateTime 2003-05-22 07:39:08 2003-05-20 22:28:45 2003-05-19 09:55:48
// ToDecimal 750999.89 631577.237188435 499999.5
// ToDouble 750999.89 631577.237188435 499999.5
// ToInt16 32767 32767 32767
// ToInt32 751000 631577 500000
// ToInt64 751000 631577 500000
// ToSByte 127 127 127
// ToSingle 750999.9 631577.3 499999.5
// ToUInt16 65535 65535 65535
// ToUInt32 751000 631577 500000
// ToUInt64 751000 631577 500000
Imports System.Collections
Module IConvertibleProviderDemo
' Define the types of averaging available in the class
' implementing IConvertible.
Enum AverageType as Short
None = 0
GeometricMean = 1
ArithmeticMean = 2
Median = 3
End Enum
' Pass an instance of this class to methods that require an
' IFormatProvider. The class instance determines the type of
' average to calculate.
Public Class AverageInfo
Implements IFormatProvider
Protected AvgType As AverageType
' Specify the type of averaging in the constructor.
Public Sub New( avgType As AverageType )
Me.AvgType = avgType
End Sub
' This method returns a reference to the containing object
' if an object of AverageInfo type is requested.
Public Function GetFormat( argType As Type ) As Object _
Implements IFormatProvider.GetFormat
If argType Is GetType( AverageInfo ) Then
Return Me
Else
Return Nothing
End If
End Function
' Use this property to set or get the type of averaging.
Public Property TypeOfAverage( ) As AverageType
Get
Return Me.AvgType
End Get
Set( ByVal value as AverageType )
Me.AvgType = value
End Set
End Property
End Class
' This class encapsulates an array of Double values and implements
' the IConvertible interface. Most of the IConvertible methods
' return an average of the array elements in one of three types:
' arithmetic mean, geometric mean, or median.
Public Class DataSet
Implements IConvertible
Protected data As ArrayList
Protected defaultProvider As AverageInfo
' Construct the object and add an initial list of values.
' Create a default format provider.
Public Sub New( ParamArray values( ) As Double )
data = New ArrayList( values )
defaultProvider = New AverageInfo( _
AverageType.ArithmeticMean )
End Sub
' Add additional values with this method.
Public Function Add( value As Double ) As Integer
data.Add( value )
Return data.Count
End Function
' Get, set, and add values with this indexer property.
Default Public Property Item(index As Integer) As Double
Get
If index >= 0 AndAlso index < data.Count Then
Return System.Convert.ToDouble( data( index ) )
Else
Throw New InvalidOperationException( _
"[DataSet.get] Index out of range." )
End If
End Get
Set
If index >= 0 AndAlso index < data.Count Then
data( index ) = value
ElseIf index = data.Count Then
data.Add( value )
Else
Throw New InvalidOperationException( _
"[DataSet.set] Index out of range." )
End If
End Set
End Property
' This property returns the number of elements in the object.
Public ReadOnly Property Count( ) As Integer
Get
Return data.Count
End Get
End Property
' This method calculates the average of the object's elements.
Protected Function Average( ByVal avgType As AverageType ) As Double
Dim SumProd As Double
Dim Index As Integer
If data.Count = 0 Then Return 0.0
Select Case avgType
Case AverageType.GeometricMean
SumProd = 1.0
For Index = 0 To data.Count - 1
SumProd *= data( Index )
Next Index
' This calculation will not fail with negative
' elements.
Return Math.Sign( SumProd ) * Math.Pow( _
Math.Abs( SumProd ), 1.0 / data.Count )
Case AverageType.ArithmeticMean
SumProd = 0.0
For Index = 0 To data.Count - 1
SumProd += data( Index )
Next Index
Return SumProd / data.Count
Case AverageType.Median
If data.Count Mod 2 = 0 Then
Return ( data( data.Count \ 2 ) + _
data( data.Count \ 2 - 1 ) ) / 2.0
Else
Return data( data.Count \ 2 )
End If
End Select
End Function
' Get the AverageInfo object from the caller's format
' provider, or use the local default.
Protected Function GetAverageInfo( _
provider As IFormatProvider ) As AverageInfo
Dim avgInfo As AverageInfo = Nothing
If Not provider Is Nothing Then
avgInfo = provider.GetFormat( GetType( AverageInfo ) )
End If
Return IIf( avgInfo Is Nothing, defaultProvider, avgInfo )
End Function
' Calculate the average and limit the range.
Protected Function CalcNLimitAverage( min As Double, _
max As Double, provider as IFormatProvider ) As Double
' Get the format provider and calculate the average.
Dim avgInfo As AverageInfo = GetAverageInfo( provider )
Dim avg As Double = Average( avgInfo.TypeOfAverage )
' Limit the range, based on the minimum and maximum values
' for the type.
Return IIf( avg > max, max, IIf( avg < min, min, avg ) )
End Function
' The following elements are required by IConvertible.
' None of these conversion functions throw exceptions. When
' the data is out of range for the type, the appropriate
' MinValue or MaxValue is used.
Public Function GetTypeCode( ) As TypeCode _
Implements IConvertible.GetTypeCode
Return TypeCode.Object
End Function
Function ToBoolean( ByVal provider As IFormatProvider ) As _
Boolean Implements IConvertible.ToBoolean
' ToBoolean is false if the dataset is empty.
If data.Count <= 0 Then
Return False
' For median averaging, ToBoolean is true if any
' non-discarded elements are nonzero.
ElseIf AverageType.Median = _
GetAverageInfo( provider ).TypeOfAverage Then
If data.Count Mod 2 = 0 Then
Return ( data( data.Count \ 2 ) <> 0.0 Or _
data( data.Count \ 2 - 1 ) <> 0.0 )
Else
Return data( data.Count \ 2 ) <> 0.0
End If
' For arithmetic or geometric mean averaging, ToBoolean is
' true if any element of the dataset is nonzero.
Else
Dim Index As Integer
For Index = 0 To data.Count - 1
If data( Index ) <> 0.0 Then Return True
Next Index
Return False
End If
End Function
Function ToByte( ByVal provider As IFormatProvider ) As Byte _
Implements IConvertible.ToByte
Return Convert.ToByte( CalcNLimitAverage( _
Byte.MinValue, Byte.MaxValue, provider ) )
End Function
Function ToChar( ByVal provider As IFormatProvider ) As Char _
Implements IConvertible.ToChar
Return Convert.ToChar( Convert.ToUInt16( _
CalcNLimitAverage( 0.0, &HFFFF, provider ) ) )
End Function
' Convert to DateTime by adding the calculated average as
' seconds to the current date and time. A valid DateTime is
' always returned.
Function ToDateTime( ByVal provider As IFormatProvider ) As _
DateTime Implements IConvertible.ToDateTime
Dim seconds As Double = Average( _
GetAverageInfo( provider ).TypeOfAverage )
Try
Return DateTime.Now.AddSeconds( seconds )
Catch ex As ArgumentOutOfRangeException
Return IIf( seconds < 0.0, DateTime.MinValue, _
DateTime.MaxValue )
End Try
End Function
Function ToDecimal( ByVal provider As IFormatProvider ) As _
Decimal Implements IConvertible.ToDecimal
' The Double conversion rounds Decimal.MinValue and
' Decimal.MaxValue to invalid Decimal values, so the
' following limits must be used.
Return Convert.ToDecimal( CalcNLimitAverage( _
-79228162514264330000000000000.0, _
79228162514264330000000000000.0, provider ) )
End Function
Function ToDouble( ByVal provider As IFormatProvider) As _
Double Implements IConvertible.ToDouble
Return Average( GetAverageInfo( provider ).TypeOfAverage )
End Function
Function ToInt16( ByVal provider As IFormatProvider ) As _
Short Implements IConvertible.ToInt16
Return Convert.ToInt16( CalcNLimitAverage( _
Int16.MinValue, Int16.MaxValue, provider ) )
End Function
Function ToInt32( ByVal provider As IFormatProvider ) As _
Integer Implements IConvertible.ToInt32
Return Convert.ToInt32( CalcNLimitAverage( _
Int32.MinValue, Int32.MaxValue, provider ) )
End Function
Function ToInt64( ByVal provider As IFormatProvider ) As Long _
Implements IConvertible.ToInt64
' The Double conversion rounds Int64.MinValue and
' Int64.MaxValue to invalid Long values, so the following
' limits must be used.
Return Convert.ToInt64( CalcNLimitAverage( _
-9223372036854775000, 9223372036854775000, provider ) )
End Function
Function ToSByte( ByVal provider As IFormatProvider ) As _
SByte Implements IConvertible.ToSByte
' SByte.MinValue and SByte.MaxValue are not defined in
' Visual Basic.
Return Convert.ToSByte( CalcNLimitAverage( _
-128, 127, provider ) )
End Function
Function ToSingle( ByVal provider As IFormatProvider ) As _
Single Implements IConvertible.ToSingle
Return Convert.ToSingle( CalcNLimitAverage( _
Single.MinValue, Single.MaxValue, provider ) )
End Function
Function ToUInt16( ByVal provider As IFormatProvider ) As _
UInt16 Implements IConvertible.ToUInt16
' UInt16.MinValue and UInt16.MaxValue are not defined in
' Visual Basic.
Return Convert.ToUInt16( CalcNLimitAverage( _
0, &HFFFF, provider ) )
End Function
Function ToUInt32( ByVal provider As IFormatProvider ) As _
UInt32 Implements IConvertible.ToUInt32
' UInt32.MinValue and UInt32.MaxValue are not defined in
' Visual Basic.
Return Convert.ToUInt32( CalcNLimitAverage( _
0, 4294967295, provider ) )
End Function
Function ToUInt64( ByVal provider As IFormatProvider ) As _
UInt64 Implements IConvertible.ToUInt64
' UInt64.MinValue and UInt64.MaxValue are not defined in
' Visual Basic. The Double conversion would have rounded
' UInt64.MaxValue, so the following limit must be used.
Return Convert.ToUInt64( CalcNLimitAverage( _
0, 18446744073709550000.0, provider ) )
End Function
Function ToType( ByVal conversionType As Type, _
ByVal provider As IFormatProvider) As Object _
Implements IConvertible.ToType
Return Convert.ChangeType( Average( GetAverageInfo( _
provider ).TypeOfAverage ), conversionType )
End Function
Overloads Function ToString( ByVal provider As IFormatProvider _
) As String Implements IConvertible.ToString
Dim avgType as AverageType = _
GetAverageInfo( provider ).TypeOfAverage
Return String.Format( "( {0}: {1:G10} )", avgType, _
Average( avgType ) )
End Function
End Class
' Display a DataSet with three different format providers.
Sub DisplayDataSet( ds As DataSet )
Dim fmt As String = "{0,-12}{1,20}{2,20}{3,20}"
Dim median As AverageInfo = New AverageInfo( AverageType.Median )
Dim geMean As AverageInfo = _
New AverageInfo( AverageType.GeometricMean )
Dim iX As Integer
' Display the dataset elements.
If ds.Count > 0 Then
Console.Write( vbCrLf & "DataSet: [{0}", ds( 0 ) )
For iX = 1 To ds.Count - 1
Console.Write( ", {0}", ds( iX ) )
Next iX
Console.WriteLine( "]" & vbCrLf )
End If
Console.WriteLine( fmt, "Convert.", "Default", _
"Geometric Mean", "Median" )
Console.WriteLine( fmt, "--------", "-------", _
"--------------", "------" )
Console.WriteLine( fmt, "ToBoolean", _
Convert.ToBoolean( ds, Nothing ), _
Convert.ToBoolean( ds, geMean ), _
Convert.ToBoolean( ds, median ) )
Console.WriteLine( fmt, "ToByte", _
Convert.ToByte( ds, Nothing ), _
Convert.ToByte( ds, geMean ), _
Convert.ToByte( ds, median ) )
Console.WriteLine( fmt, "ToChar", _
Convert.ToChar( ds, Nothing ), _
Convert.ToChar( ds, geMean ), _
Convert.ToChar( ds, median ) )
Console.WriteLine( "{0,-12}{1,20:yyyy-MM-dd HH:mm:ss}" & _
"{2,20:yyyy-MM-dd HH:mm:ss}{3,20:yyyy-MM-dd HH:mm:ss}", _
"ToDateTime", Convert.ToDateTime( ds, Nothing ), _
Convert.ToDateTime( ds, geMean ), _
Convert.ToDateTime( ds, median ) )
Console.WriteLine( fmt, "ToDecimal", _
Convert.ToDecimal( ds, Nothing ), _
Convert.ToDecimal( ds, geMean ), _
Convert.ToDecimal( ds, median ) )
Console.WriteLine( fmt, "ToDouble", _
Convert.ToDouble( ds, Nothing ), _
Convert.ToDouble( ds, geMean ), _
Convert.ToDouble( ds, median ) )
Console.WriteLine( fmt, "ToInt16", _
Convert.ToInt16( ds, Nothing ), _
Convert.ToInt16( ds, geMean ), _
Convert.ToInt16( ds, median ) )
Console.WriteLine( fmt, "ToInt32", _
Convert.ToInt32( ds, Nothing ), _
Convert.ToInt32( ds, geMean ), _
Convert.ToInt32( ds, median ) )
Console.WriteLine( fmt, "ToInt64", _
Convert.ToInt64( ds, Nothing ), _
Convert.ToInt64( ds, geMean ), _
Convert.ToInt64( ds, median ) )
Console.WriteLine( fmt, "ToSByte", _
Convert.ToSByte( ds, Nothing ), _
Convert.ToSByte( ds, geMean ), _
Convert.ToSByte( ds, median ) )
Console.WriteLine( fmt, "ToSingle", _
Convert.ToSingle( ds, Nothing ), _
Convert.ToSingle( ds, geMean ), _
Convert.ToSingle( ds, median ) )
Console.WriteLine( fmt, "ToUInt16", _
Convert.ToUInt16( ds, Nothing ), _
Convert.ToUInt16( ds, geMean ), _
Convert.ToUInt16( ds, median ) )
Console.WriteLine( fmt, "ToUInt32", _
Convert.ToUInt32( ds, Nothing ), _
Convert.ToUInt32( ds, geMean ), _
Convert.ToUInt32( ds, median ) )
Console.WriteLine( fmt, "ToUInt64", _
Convert.ToUInt64( ds, Nothing ), _
Convert.ToUInt64( ds, geMean ), _
Convert.ToUInt64( ds, median ) )
End Sub
Sub Main( )
Console.WriteLine( _
"This example of the Convert.To<Type>( Object, " & _
"IFormatProvider ) methods " & vbCrLf & "generates " & _
"the following output. The example displays the " & _
"values " & vbCrLf & "returned by the methods, " & _
"using several IFormatProvider objects." & vbCrLf )
Dim ds1 As New DataSet( 10.5, 22.2, 45.9, 88.7, 156.05, 297.6 )
DisplayDataSet( ds1 )
Dim ds2 As New DataSet( _
359999.95, 425000, 499999.5, 775000, 1695000 )
DisplayDataSet( ds2 )
End Sub
End Module
' This example of the Convert.To<Type>( Object, IFormatProvider ) methods
' generates the following output. The example displays the values
' returned by the methods, using several IFormatProvider objects.
'
' DataSet: [10.5, 22.2, 45.9, 88.7, 156.05, 297.6]
'
' Convert. Default Geometric Mean Median
' -------- ------- -------------- ------
' ToBoolean True True True
' ToByte 103 59 67
' ToChar g ; C
' ToDateTime 2003-05-13 14:52:53 2003-05-13 14:52:09 2003-05-13 14:52:17
' ToDecimal 103.491666666667 59.4332135445164 67.3
' ToDouble 103.491666666667 59.4332135445164 67.3
' ToInt16 103 59 67
' ToInt32 103 59 67
' ToInt64 103 59 67
' ToSByte 103 59 67
' ToSingle 103.4917 59.43321 67.3
' ToUInt16 103 59 67
' ToUInt32 103 59 67
' ToUInt64 103 59 67
'
' DataSet: [359999.95, 425000, 499999.5, 775000, 1695000]
'
' Convert. Default Geometric Mean Median
' -------- ------- -------------- ------
' ToBoolean True True True
' ToByte 255 255 255
' ToChar ? ? ?
' ToDateTime 2003-05-22 07:27:49 2003-05-20 22:17:27 2003-05-19 09:44:29
' ToDecimal 750999.89 631577.237188435 499999.5
' ToDouble 750999.89 631577.237188435 499999.5
' ToInt16 32767 32767 32767
' ToInt32 751000 631577 500000
' ToInt64 751000 631577 500000
' ToSByte 127 127 127
' ToSingle 750999.9 631577.3 499999.5
' ToUInt16 65535 65535 65535
' ToUInt32 751000 631577 500000
' ToUInt64 751000 631577 500000
Megjegyzések
provider lehetővé teszi a felhasználó számára, hogy kultúraspecifikus konverziós információkat adjon meg a tartalomról value. Az alaptípusok figyelmen kívül hagyják a provider paramétert, de a paraméter akkor is használható, ha value egy felhasználó által definiált típus, amely implementálja az interfészt IConvertible .
Lásd még
A következőre érvényes:
ToBoolean(UInt64)
Fontos
Ez az API nem CLS-kompatibilis.
A megadott 64 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::UInt64 value);[System.CLSCompliant(false)]
public static bool ToBoolean(ulong value);[<System.CLSCompliant(false)>]
static member ToBoolean : uint64 -> boolPublic Shared Function ToBoolean (value As ULong) As BooleanParaméterek
- value
- UInt64
Az átalakítandó 64 bites aláíratlan egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
- Attribútumok
Példák
Az alábbi példa egy értéktömböt UInt64 konvertál értékké Boolean .
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
let numbers =
[| UInt64.MinValue; 6121uL; 403890774uL; UInt64.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-26:N0} --> {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
Lásd még
A következőre érvényes:
ToBoolean(UInt32)
Fontos
Ez az API nem CLS-kompatibilis.
A megadott 32 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::UInt32 value);[System.CLSCompliant(false)]
public static bool ToBoolean(uint value);[<System.CLSCompliant(false)>]
static member ToBoolean : uint32 -> boolPublic Shared Function ToBoolean (value As UInteger) As BooleanParaméterek
- value
- UInt32
Az átalakítandó 32 bites aláíratlan egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
- Attribútumok
Példák
Az alábbi példa egy értéktömböt Int32 konvertál értékké Boolean .
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
let numbers =
[| UInt32.MinValue; 612u; 4038907u; uint Int32.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-15:N0} --> {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
Lásd még
A következőre érvényes:
ToBoolean(UInt16)
Fontos
Ez az API nem CLS-kompatibilis.
A megadott 16 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::UInt16 value);[System.CLSCompliant(false)]
public static bool ToBoolean(ushort value);[<System.CLSCompliant(false)>]
static member ToBoolean : uint16 -> boolPublic Shared Function ToBoolean (value As UShort) As BooleanParaméterek
- value
- UInt16
Az átalakítandó 16 bites aláíratlan egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
- Attribútumok
Példák
Az alábbi példa egy értéktömböt UInt16 konvertál értékké Boolean .
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
let numbers =
[| UInt16.MinValue; 216us; 21453us; UInt16.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-7:N0} --> {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
Lásd még
A következőre érvényes:
ToBoolean(String)
Egy logikai érték megadott sztring-ábrázolását logikai megfelelővé alakítja.
public:
static bool ToBoolean(System::String ^ value);public static bool ToBoolean(string value);static member ToBoolean : string -> boolPublic Shared Function ToBoolean (value As String) As BooleanParaméterek
- value
- String
Egy sztring, amely a következő értékeket tartalmazza: vagy TrueStringFalseString.
Válaszok
trueha value egyenlő, vagy false egyenlő valueFalseString vagy null.TrueString
Kivételek
value nem egyenlő vagy TrueStringFalseString.
Példák
Az alábbi példa a metódus használatával konvertálja a Convert.ToBoolean(String) különböző sztringeket logikai értékekké.
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.
open System
let values =
[| null; String.Empty; "true"; "TrueString"
"False"; " false "; "-1"; "0" |]
for value in values do
try
printfn $"Converted '{value}' to {Convert.ToBoolean value}."
with :? FormatException ->
printfn $"Unable to convert '{value}' to a Boolean."
// 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.
Megjegyzések
A sikeres átalakításhoz a paraméternek vagy Boolean.TrueStringegyenlőnek kell lennie , egy állandónak, amelynek értéke True, Boolean.FalseStringegy állandó, amelynek értéke False, vagy annak kell lennie null.value Összehasonlítva valueBoolean.TrueString az és Boolean.FalseString, a metódus figyelmen kívül hagyja az esetet, valamint a vezető és a záró szóköz.
Ha inkább nem szeretne kivételt kezelni, ha az átalakítás sikertelen, hívhatja meg helyette a metódust Boolean.TryParse . Egy értéket ad Boolean vissza, amely jelzi, hogy az átalakítás sikeres volt-e vagy nem sikerült.
Lásd még
A következőre érvényes:
ToBoolean(Single)
A megadott egypontos lebegőpontos szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(float value);public static bool ToBoolean(float value);static member ToBoolean : single -> boolPublic Shared Function ToBoolean (value As Single) As BooleanParaméterek
- value
- Single
Az átalakítandó egy pontosságú lebegőpontos szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy értéktömböt Single konvertál értékké Boolean .
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
let numbers =
[| Single.MinValue; -193.0012f; 20e-15f; 0f
10551e-10f; 100.3398f; Single.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-15} --> {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
Lásd még
A következőre érvényes:
ToBoolean(Object)
Egy adott objektum értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::Object ^ value);public static bool ToBoolean(object value);static member ToBoolean : obj -> boolPublic Shared Function ToBoolean (value As Object) As BooleanParaméterek
- value
- Object
Az interfészt megvalósító IConvertible objektum, vagy null.
Válaszok
truevagy false, amely az alapul szolgáló típus valuemetódusának meghívásával ToBoolean(IFormatProvider) visszaadott értéket tükrözi. Ha value igen null, a metódus visszaadja false.
Kivételek
value olyan sztring, amely nem egyenlő TrueString vagy FalseString.
value nem implementálja az interfészt IConvertible .
-vagy-
A konvertálás valueBoolean nem támogatott.
Példák
Az alábbi példa egy objektumértékeket tartalmazó tömböt konvertál értékké Boolean .
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
let objects: obj[] =
[| 16.33; -24; 0; "12"; "12.7"; String.Empty
"1String"; "True"; "false"; null
System.Collections.ArrayList() |]
for obj in objects do
printf $"""{(if obj <> null then $"{obj} ({obj.GetType().Name})" else "null"),-40} --> """
try
Console.WriteLine("{0}", Convert.ToBoolean(obj))
with
| :? FormatException ->
printfn "Bad Format"
| :? InvalidCastException ->
printfn "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
Lásd még
A következőre érvényes:
ToBoolean(Double)
A megadott dupla pontosságú lebegőpontos szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(double value);public static bool ToBoolean(double value);static member ToBoolean : double -> boolPublic Shared Function ToBoolean (value As Double) As BooleanParaméterek
- value
- Double
Az átalakítandó dupla pontosságú lebegőpontos szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy logikai értéket és egy DoubleDouble logikai értéket ad át.
public void ConvertDoubleBool(double doubleVal) {
bool boolVal;
// Double to bool conversion cannot overflow.
boolVal = System.Convert.ToBoolean(doubleVal);
System.Console.WriteLine("{0} as a Boolean is: {1}.",
doubleVal, boolVal);
// bool to double conversion cannot overflow.
doubleVal = System.Convert.ToDouble(boolVal);
System.Console.WriteLine("{0} as a double is: {1}.",
boolVal, doubleVal);
}
let convertDoubleBool (doubleVal: float) =
// Double to bool conversion cannot overflow.
let boolVal = Convert.ToBoolean doubleVal
printfn $"{doubleVal} as a Boolean is: {boolVal}."
// bool to double conversion cannot overflow.
let doubleVal = Convert.ToDouble boolVal
printfn $"{boolVal} as a double is: {doubleVal}."
Public Sub ConvertDoubleBool(ByVal doubleVal As Double)
Dim boolVal As Boolean
'Double to Boolean conversion cannot overflow.
boolVal = System.Convert.ToBoolean(doubleVal)
System.Console.WriteLine("{0} as a Boolean is: {1}.", _
doubleVal, boolVal)
'Boolean to Double conversion cannot overflow.
doubleVal = System.Convert.ToDouble(boolVal)
System.Console.WriteLine("{0} as a Double is: {1}.", _
boolVal, doubleVal)
End Sub
Lásd még
A következőre érvényes:
ToBoolean(Int32)
A megadott 32 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(int value);public static bool ToBoolean(int value);static member ToBoolean : int -> boolPublic Shared Function ToBoolean (value As Integer) As BooleanParaméterek
- value
- Int32
A konvertálni kívánt 32 bites aláírt egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy értéktömböt Int32 konvertál értékké Boolean .
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
let numbers =
[| Int32.MinValue; -201649; -68; 0
612; 4038907; Int32.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-15:N0} --> {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
Lásd még
A következőre érvényes:
ToBoolean(Int16)
A megadott 16 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(short value);public static bool ToBoolean(short value);static member ToBoolean : int16 -> boolPublic Shared Function ToBoolean (value As Short) As BooleanParaméterek
- value
- Int16
A konvertálandó 16 bites aláírt egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy értéktömböt Int16 konvertál értékké Boolean .
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
let numbers =
[| Int16.MinValue; -10000s; -154s; 0s
216s; 21453s; Int16.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-7:N0} --> {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
Lásd még
A következőre érvényes:
ToBoolean(Decimal)
A megadott decimális szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::Decimal value);public static bool ToBoolean(decimal value);static member ToBoolean : decimal -> boolPublic Shared Function ToBoolean (value As Decimal) As BooleanParaméterek
- value
- Decimal
Az átalakítandó szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy értéktömböt Decimal konvertál értékké Boolean .
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
let numbers =
[| Decimal.MinValue; -12034.87m; -100m; 0m
300m; 6790823.45m; Decimal.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-30} --> {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
Lásd még
A következőre érvényes:
ToBoolean(DateTime)
Ennek a metódusnak a meghívása InvalidCastExceptionmindig dob.
public:
static bool ToBoolean(DateTime value);public static bool ToBoolean(DateTime value);static member ToBoolean : DateTime -> boolPublic Shared Function ToBoolean (value As DateTime) As BooleanParaméterek
- value
- DateTime
Az átalakítandó dátum- és időérték.
Válaszok
Ez az átalakítás nem támogatott. A függvény nem ad vissza értéket.
Kivételek
Ez az átalakítás nem támogatott.
Példák
Az alábbi példa azt mutatja be, hogy egy DateTime érték logikai típussá való konvertálásának kísérlete InvalidCastExceptiondob.
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.");
}
}
let convertBoolean () =
let year = 1979
let month = 7
let day = 28
let hour = 13
let minute = 26
let second = 15
let millisecond = 53
let dateTime = DateTime(year, month, day, hour, minute, second, millisecond)
// System.InvalidCastException is always thrown.
try
let boolVal = Convert.ToBoolean dateTime
()
with :? InvalidCastException ->
printfn "Conversion from DateTime to Boolean is not supported by the .NET Runtime."
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
A következőre érvényes:
ToBoolean(Char)
Ennek a metódusnak a meghívása InvalidCastExceptionmindig dob.
public:
static bool ToBoolean(char value);public static bool ToBoolean(char value);static member ToBoolean : char -> boolPublic Shared Function ToBoolean (value As Char) As BooleanParaméterek
- value
- Char
Az átalakítandó Unicode-karakter.
Válaszok
Ez az átalakítás nem támogatott. A függvény nem ad vissza értéket.
Kivételek
Ez az átalakítás nem támogatott.
Lásd még
A következőre érvényes:
ToBoolean(Byte)
A megadott 8 bites aláíratlan egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(System::Byte value);public static bool ToBoolean(byte value);static member ToBoolean : byte -> boolPublic Shared Function ToBoolean (value As Byte) As BooleanParaméterek
- value
- Byte
Az átalakítandó 8 bites aláíratlan egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy értéktömböt Byte konvertál értékké Boolean .
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
let bytes = [| Byte.MinValue; 100uy; 200uy; Byte.MaxValue |]
for byteValue in bytes do
let result = Convert.ToBoolean byteValue
printfn $"{byteValue,-5} --> {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
Lásd még
A következőre érvényes:
ToBoolean(Boolean)
A megadott logikai értéket adja vissza; nincs tényleges átalakítás.
public:
static bool ToBoolean(bool value);public static bool ToBoolean(bool value);static member ToBoolean : bool -> boolPublic Shared Function ToBoolean (value As Boolean) As BooleanParaméterek
- value
- Boolean
A visszaadandó logikai érték.
Válaszok
value a visszaadott érték változatlan marad.
Lásd még
A következőre érvényes:
ToBoolean(Int64)
A megadott 64 bites aláírt egész szám értékét egyenértékű logikai értékké alakítja.
public:
static bool ToBoolean(long value);public static bool ToBoolean(long value);static member ToBoolean : int64 -> boolPublic Shared Function ToBoolean (value As Long) As BooleanParaméterek
- value
- Int64
A konvertálni kívánt 64 bites aláírt egész szám.
Válaszok
trueha value nem nulla; ellenkező esetben. false
Példák
Az alábbi példa egy értéktömböt Int64 konvertál értékké Boolean .
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
let numbers =
[| Int64.MinValue; -2016493; -689
0; 6121; 403890774; Int64.MaxValue |]
for number in numbers do
let result = Convert.ToBoolean number
printfn $"{number,-26:N0} --> {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