Convert.ToInt16 Method (Object, IFormatProvider)
Converts the value of the specified object to a 16-bit signed integer, using the specified culture-specific formatting information.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
-
Type:
System.Object
An object that implements the IConvertible interface.
- provider
-
Type:
System.IFormatProvider
An object that supplies culture-specific formatting information.
Return Value
Type: System.Int16A 16-bit signed integer that is equivalent to value, or zero if value is null.
| Exception | Condition |
|---|---|
| FormatException | value is not in an appropriate format for an Int16 type. |
| InvalidCastException | value does not implement IConvertible. |
| OverflowException | value represents a number that is less than Int16.MinValue or greater than Int16.MaxValue. |
provider enables the user to specify culture-specific conversion information about the contents of value. For example, if value is a String that represents a number, provider could supply culture-specific information about the notation used to represent that number.
The base types ignore provider; however, the parameter may be used if value is a user-defined type that implements the IConvertible interface.
The following example defines a class that implements IConvertible and a class that implements IFormatProvider. Objects of the class that implements IConvertible hold an array of Double values. An object of each class is passed to the ToInt16 method. This method returns an average of the array of Double values, using the object that implements IFormatProvider to determine how to calculate the average.
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
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1