IFormatProvider (Interfaz)
Proporciona un mecanismo para recuperar un objeto con el fin de controlar el formato.
Espacio de nombres: System
Ensamblado: mscorlib (en mscorlib.dll)
Ensamblado: mscorlib (en mscorlib.dll)
Algunos métodos en Common Language Runtime convierten un valor a o desde una representación de cadena y toman un parámetro de cadena que contiene uno o más caracteres, denominados especificadores de formato, que indican la forma de convertir el valor. Si el significado del especificador de formato varía en función de la referencia cultural, un objeto de formato suministra los caracteres actuales utilizados en la representación de cadena.
Una clase, o un tipo de valor, implementa el método GetFormat de esta interfaz para obtener un objeto que proporcione información de formato o procesamiento para el tipo de implementación pertinente.
Por ejemplo, NumberFormatInfo y DateTimeFormatInfo implementan IFormatProvider. NumberFormatInfo proporciona información específica sobre la referencia cultural utilizada para dar formato a números en los tipos de datos base y DateTimeFormatInfo proporciona información específica sobre la referencia cultural utilizada para dar formato a los valores de fecha y hora.
En el siguiente ejemplo de código se muestra el uso de una clase que implementa la interfaz IFormatProvider y el método GetFormat. La clase AnyRadix admite el código de formato "Ra" y convierte un valor Int64 en una cadena de cualquier base especificada entre 2 y 36. GetFormat devuelve una referencia a sí mismo si el parámetro Type hace referencia a una clase que implementa ICustomFormatter; en caso contrario, GetFormat devuelve el valor referencia de objeto null (Nothing en Visual Basic).
// Sample for the IFormatProvider interface and // the IFormatProvider.GetFormat( Type ) method. using System; // This class implements the "Ra" formatting code. An instance of this // class should be passed to methods requiring an IFormatProvider. public class AnyRadix : ICustomFormatter, IFormatProvider { // The value to be formatted is returned as a signed string // of digits from the rDigits array. const string radixCode = "Ra"; private static char[] rDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' }; // This method returns an object that implements ICustomFormatter // to do the formatting. public object GetFormat( Type argType ) { // Here, the same object (this) is returned, but it would // be possible to return an object of a different type. if ( argType == typeof( ICustomFormatter ) ) return this; else return null; } // This method does the formatting only if it recognizes the // format codes. public string Format( string formatString, object argToBeFormatted, IFormatProvider provider ) { // If no format string is provided or the format string cannot // be handled, use IFormattable or standard string processing. if( formatString == null || ! formatString.Trim( ).StartsWith( radixCode ) ) { if( argToBeFormatted is IFormattable ) return ( (IFormattable)argToBeFormatted ). ToString( formatString, provider ); else return argToBeFormatted.ToString( ); } // The formatting is handled here. int digitIndex = 0; long radix; long longToBeFormatted; long longPositive; char[ ] outDigits = new char[ 63 ]; // Extract the radix from the format string. formatString = formatString.Replace( radixCode, "" ); try { radix = Convert.ToInt64( formatString ); } catch( Exception ex ) { throw new ArgumentException( String.Format( "The radix \"{0}\" is invalid.", formatString ), ex ); } // Verify that the radix is in the proper range. if( radix <2 || radix > 36 ) throw new ArgumentException( String.Format( "The radix \"{0}\" is not in the range 2..36.", formatString ) ); // Verify that the argument can be converted to a long integer. try { longToBeFormatted = (long)argToBeFormatted; } catch( Exception ex ) { throw new ArgumentException( String.Format( "The argument \"{0}\" cannot be " + "converted to an integer value.", argToBeFormatted ), ex ); } // Extract the magnitude for conversion. longPositive = Math.Abs( longToBeFormatted ); // Convert the magnitude to a digit string. for( digitIndex = 0; digitIndex <= 64; digitIndex++ ) { if( longPositive == 0 ) break; outDigits[ outDigits.Length - digitIndex - 1 ] = rDigits[ longPositive % radix ]; longPositive /= radix; } // Add a minus sign if the argument is negative. if( longToBeFormatted < 0 ) outDigits[ outDigits.Length - digitIndex++ - 1 ] = '-'; return new string( outDigits, outDigits.Length - digitIndex, digitIndex ); } } class IFormatProviderDemo { static void ConvertToAnyRadix( object argToConvert, string formatStr ) { AnyRadix provider = new AnyRadix( ); string messageStr = String.Format( "{{0:{0}}}", formatStr ); // Write the first part of the output line. Console.Write( "{0,18} {1,-6}", argToConvert, formatStr ); // Convert the specified argument using the specified format. try { Console.WriteLine( String.Format( provider, messageStr, argToConvert ) ); } catch( Exception ex ) { // Display the exception without the stack trace. int lineEnd = ex.ToString( ).IndexOf( '\n' ); Console.WriteLine( "{0}\n", ex.ToString( ).Substring( 0, lineEnd ) ); } } static void Main( ) { long twoToThe32 = 4294967296; long fifteenNines = 999999999999999; Console.WriteLine( "This example of the IFormatProvider interface \n" + "and the IFormatProvider.GetFormat( Type ) method " + "\ngenerates the following output.\n" ); Console.WriteLine( "{0,18} Format Result", "Number" ); Console.WriteLine( "{0,18} ------ ------", "------" ); // These are valid conversions. ConvertToAnyRadix( twoToThe32, "Ra2" ); ConvertToAnyRadix( twoToThe32, "Ra5" ); ConvertToAnyRadix( twoToThe32, "Ra16" ); ConvertToAnyRadix( twoToThe32, "Ra23" ); ConvertToAnyRadix( twoToThe32, "Ra36" ); ConvertToAnyRadix( fifteenNines, "Ra2" ); ConvertToAnyRadix( fifteenNines, "Ra3" ); ConvertToAnyRadix( fifteenNines, "Ra8" ); ConvertToAnyRadix( fifteenNines, "Ra11" ); ConvertToAnyRadix( fifteenNines, "Ra16" ); ConvertToAnyRadix( fifteenNines, "Ra23" ); ConvertToAnyRadix( fifteenNines, "Ra36" ); ConvertToAnyRadix( fifteenNines, "E16" ); ConvertToAnyRadix( fifteenNines, "" ); // These are error conditions. ConvertToAnyRadix( fifteenNines, "Ra37" ); ConvertToAnyRadix( "ABCDEFGHIJKLM", "Ra16" ); } } /* This example of the IFormatProvider interface and the IFormatProvider.GetFormat( Type ) method generates the following output. Number Format Result ------ ------ ------ 4294967296 Ra2 100000000000000000000000000000000 4294967296 Ra5 32244002423141 4294967296 Ra16 100000000 4294967296 Ra23 1606K7IC 4294967296 Ra36 1Z141Z4 999999999999999 Ra2 11100011010111111010100100110001100111111111111111 999999999999999 Ra3 11212010201001210101011021212000 999999999999999 Ra8 34327724461477777 999999999999999 Ra11 26A6A3689065639 999999999999999 Ra16 38D7EA4C67FFF 999999999999999 Ra23 1134DIFHLMM4 999999999999999 Ra36 9UGXNORJLR 999999999999999 E16 9.9999999999999900E+014 999999999999999 999999999999999 999999999999999 Ra37 System.ArgumentException: The radix "37" is not in th e range 2..36. ABCDEFGHIJKLM Ra16 System.ArgumentException: The argument "ABCDEFGHIJKLM " cannot be converted to an integer value. ---> System.InvalidCastException: Sp ecified cast is not valid. */
// Sample for the IFormatProvider interface and
// the IFormatProvider.GetFormat( Type ) method.
import System.*;
// This class implements the "Ra" formatting code. An instance of this
// class should be passed to methods requiring an IFormatProvider.
public class AnyRadix implements ICustomFormatter,IFormatProvider
{
// The value to be formatted is returned as a signed string
// of digits from the rDigits array.
private String radixCode = "Ra";
private static char rDigits[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z' };
// This method returns an object that implements ICustomFormatter
// to do the formatting.
public Object GetFormat(Type argType)
{
// Here, the same object (this) is returned, but it would
// be possible to return an object of a different type.
if ( argType.Equals(ICustomFormatter.class.ToType()) ) {
return this ;
}
else {
return null ;
}
} //GetFormat
// This method does the formatting only if it recognizes the
// format codes.
public String Format(String formatString, Object argToBeFormatted,
IFormatProvider provider)
{
// If no format string is provided or the format string cannot
// be handled, use IFormattable or standard string processing.
if(formatString == null||!(formatString.Trim().StartsWith(radixCode))) {
if ( argToBeFormatted instanceof IFormattable ) {
return((IFormattable)(argToBeFormatted)).
ToString(formatString,provider);
}
else {
return argToBeFormatted.ToString();
}
}
// The formatting is handled here.
int digitIndex = 0;
long radix;
long longToBeFormatted;
long longPositive;
char outDigits[] = new char[63];
// Extract the radix from the format string.
formatString = formatString.Replace(radixCode, "");
try {
radix = Convert.ToInt64(formatString);
}
catch(System.Exception ex) {
throw new ArgumentException(String.Format(
"The radix \"{0}\" is invalid.", formatString), ex);
}
// Verify that the radix is in the proper range.
if ( radix < 2 || radix > 36 ) {
throw new ArgumentException(String.Format(
"The radix \"{0}\" is not in the range 2..36.", formatString));
}
// Verify that the argument can be converted to a long integer.
try {
longToBeFormatted =(long)System.Convert.ToUInt64(argToBeFormatted);
}
catch(System.Exception ex) {
throw new ArgumentException(String.Format(
"The argument \"{0}\" cannot be "
+ "converted to an integer value.", argToBeFormatted), ex);
}
// Extract the magnitude for conversion.
longPositive = System.Math.Abs(longToBeFormatted);
// Convert the magnitude to a digit string.
for(digitIndex = 0;digitIndex <= 64;digitIndex++) {
if ( longPositive == 0 ) {
break ;
}
outDigits[outDigits.length - digitIndex - 1] =
rDigits[(int)(longPositive % radix)];
longPositive /= radix;
}
// Add a minus sign if the argument is negative.
if ( longToBeFormatted < 0 ) {
outDigits [outDigits.length - digitIndex ++ - 1] = '-';
}
return new String(outDigits, outDigits.length - digitIndex, digitIndex);
} //Format
} //AnyRadix
class IFormatProviderDemo
{
static void ConvertToAnyRadix(Object argToConvert, String formatStr)
{
AnyRadix provider = new AnyRadix();
String messageStr = String.Format("{{0:{0}}}", formatStr);
// Write the first part of the output line.
Console.Write("{0,18} {1,-6}", argToConvert, formatStr);
// Convert the specified argument using the specified format.
try {
Console.WriteLine(String.Format((IFormatProvider)provider,
messageStr,new Object[]{ argToConvert}));
}
catch(System.Exception ex) {
// Display the exception without the stack trace.
int lineEnd = ex.ToString().IndexOf('\n');
Console.WriteLine("{0}\n", ex.ToString().Substring(0, lineEnd));
}
} //ConvertToAnyRadix
public static void main(String[] args)
{
long twoToThe32 = 4294967296L;
long fifteenNines = 999999999999999L;
Console.WriteLine(("This example of the IFormatProvider interface \n"
+ "and the IFormatProvider.GetFormat( Type ) method "
+ "\ngenerates the following output.\n"));
Console.WriteLine("{0,18} Format Result", "Number");
Console.WriteLine("{0,18} ------ ------", "------");
// These are valid conversions.
ConvertToAnyRadix(((System.UInt64 )(twoToThe32)), "Ra2");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra5");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra16");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra23");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra36");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra2");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra3");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra8");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra11");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra16");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra23");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra36");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "E16");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "");
// These are error conditions.
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra37");
ConvertToAnyRadix("ABCDEFGHIJKLM", "Ra16");
} //main
} //IFormatProviderDemo
/*
This example of the IFormatProvider interface
and the IFormatProvider.GetFormat( Type ) method
generates the following output.
Number Format Result
------ ------ ------
4294967296 Ra2 100000000000000000000000000000000
4294967296 Ra5 32244002423141
4294967296 Ra16 100000000
4294967296 Ra23 1606K7IC
4294967296 Ra36 1Z141Z4
999999999999999 Ra2 11100011010111111010100100110001100111111111111111
999999999999999 Ra3 11212010201001210101011021212000
999999999999999 Ra8 34327724461477777
999999999999999 Ra11 26A6A3689065639
999999999999999 Ra16 38D7EA4C67FFF
999999999999999 Ra23 1134DIFHLMM4
999999999999999 Ra36 9UGXNORJLR
999999999999999 E16 9.9999999999999900E+014
999999999999999 999999999999999
999999999999999 Ra37 System.ArgumentException: The radix "37" is not in th
e range 2..36.
ABCDEFGHIJKLM Ra16 System.ArgumentException: The argument "ABCDEFGHIJKLM"
cannot be converted to an integer value. ---> System.FormatException: Input str
ing was not in a correct format.
*/
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium, Windows Mobile para Pocket PC, Windows Mobile para Smartphone, Windows Server 2003, Windows XP Media Center, Windows XP Professional x64, Windows XP SP2, Windows XP Starter Edition
.NET Framework no admite todas las versiones de cada plataforma. Para obtener una lista de las versiones admitidas, vea Requisitos del sistema.
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