Convert.ToChar Method (Object, IFormatProvider)
Converts the value of the specified object to its equivalent Unicode character, 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.CharA Unicode character that is equivalent to value, or Char.MinValue if value is null.
| Exception | Condition |
|---|---|
| ArgumentNullException | value is a null string. |
| InvalidCastException | value does not implement the IConvertible interface. -or- The conversion of value to a Char is not supported. |
| OverflowException | value is less than Char.MinValue or greater than Char.MaxValue. |
The return value is the result of invoking the IConvertible.ToChar method of the underlying type of value.
provider enables the user to specify culture-specific conversion information about the contents of value. 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 ToChar method. This method returns a character whose Unicode value is the average of the array of Double values, using the object that implements IFormatProvider to determine how to calculate the average.
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 */
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