Char.TryParse(String, Char) Método

Definición

Convierte el valor de la cadena especificada en el carácter Unicode equivalente.Converts the value of the specified string to its equivalent Unicode character. Un código devuelto indica si la conversión fue correcta o no.A return code indicates whether the conversion succeeded or failed.

public:
 static bool TryParse(System::String ^ s, [Runtime::InteropServices::Out] char % result);
public static bool TryParse (string s, out char result);
static member TryParse : string * char -> bool
Public Shared Function TryParse (s As String, ByRef result As Char) As Boolean

Parámetros

s
String

Una cadena que contiene un carácter único, o null.A string that contains a single character, or null.

result
Char

Cuando este método devuelve un valor, si la conversión se ha realizado correctamente, contiene un carácter Unicode equivalente al único carácter de s; si se ha producido un error en la conversión, contiene un valor indefinido.When this method returns, contains a Unicode character equivalent to the sole character in s, if the conversion succeeded, or an undefined value if the conversion failed. Se produce un error en la conversión si el parámetro s es null o la longitud de s no es 1.The conversion fails if the s parameter is null or the length of s is not 1. Este parámetro se pasa sin inicializar.This parameter is passed uninitialized.

Devoluciones

true si el parámetro s se convierte correctamente; en caso contrario, false.true if the s parameter was converted successfully; otherwise, false.

Ejemplos

En el ejemplo de código siguiente se muestran las sobrecargas del TryParse método para varios tipos base y el TryParseExact método DateTime para el tipo base.The following code example demonstrates overloads of the TryParse method for several base types, and the TryParseExact method for the DateTime base type.

// This example demonstrates overloads of the TryParse method for
// several base types, and the TryParseExact method for DateTime.
// In most cases, this example uses the most complex overload; that is, the overload
// with the most parameters for a particular type. If a complex overload specifies
// null (Nothing in Visual Basic) for the IFormatProvider parameter, formatting
// information is obtained from the culture associated with the current thread.
// If a complex overload specifies the style parameter, the parameter value is
// the default value used by the equivalent simple overload.
using namespace System;
using namespace System::Globalization;

static void Show( bool parseResult, String^ typeName, String^ parseValue )
{
   String^ msgSuccess = L"Parse for {0} = {1}";
   String^ msgFailure = L"** Parse for {0} failed. Invalid input.";
   
   //
   if ( parseResult == true )
      Console::WriteLine( msgSuccess, typeName, parseValue );
   else
      Console::WriteLine( msgFailure, typeName );
}

void main()
{
   bool result;
   CultureInfo^ ci;
   String^ nl = Environment::NewLine;
   String^ msg1 = L"This example demonstrates overloads of the TryParse method for{0}"
   L"several base types, as well as the TryParseExact method for DateTime.{0}";
   String^ msg2 = L"Non-numeric types:{0}";
   String^ msg3 = L"{0}Numeric types:{0}";
   String^ msg4 = L"{0}The following types are not CLS-compliant:{0}";
   
   // Non-numeric types.
   Boolean booleanVal;
   Char charVal;
   DateTime datetimeVal;
   
   // Numeric types.
   Byte byteVal;
   Int16 int16Val;
   Int32 int32Val;
   Int64 int64Val;
   Decimal decimalVal;
   Single singleVal;
   Double doubleVal;
   
   // The following types are not CLS-compliant.
   SByte sbyteVal;
   UInt16 uint16Val;
   UInt32 uint32Val;
   UInt64 uint64Val;
   
   //
   Console::WriteLine( msg1, nl );
   
   // Non-numeric types:
   Console::WriteLine( msg2, nl );
   
   // DateTime
   // TryParse:
   // Assume current culture is en-US, and dates of the form: MMDDYYYY.
   result = DateTime::TryParse( L"7/4/2004 12:34:56",  datetimeVal );
   Show( result, L"DateTime #1", datetimeVal.ToString() );
   
   // Use fr-FR culture, and dates of the form: DDMMYYYY.
   ci = gcnew CultureInfo( L"fr-FR" );
   result = DateTime::TryParse( L"4/7/2004 12:34:56", ci, DateTimeStyles::None,  datetimeVal );
   Show( result, L"DateTime #2", datetimeVal.ToString() );
   
   // TryParseExact:
   // Use fr-FR culture. The format, "G", is short date and long time.
   result = DateTime::TryParseExact( L"04/07/2004 12:34:56", L"G", ci, DateTimeStyles::None,  datetimeVal );
   Show( result, L"DateTime #3", datetimeVal.ToString() );
   
   // Assume en-US culture.
   array<String^>^dateFormats = {L"f",L"F",L"g",L"G"};
   result = DateTime::TryParseExact( L"7/4/2004 12:34:56 PM", dateFormats, nullptr, DateTimeStyles::None,  datetimeVal );
   Show( result, L"DateTime #4", datetimeVal.ToString() );
   Console::WriteLine();
   
   // Boolean
   result = Boolean::TryParse( L"true",  booleanVal );
   Show( result, L"Boolean", booleanVal.ToString() );
   
   // Char
   result = Char::TryParse( L"A",  charVal );
   Show( result, L"Char", charVal.ToString() );
   
   // Numeric types:
   Console::WriteLine( msg3, nl );
   
   // Byte
   result = Byte::TryParse( L"1", NumberStyles::Integer, nullptr,  byteVal );
   Show( result, L"Byte", byteVal.ToString() );
   
   // Int16
   result = Int16::TryParse( L"-2", NumberStyles::Integer, nullptr,  int16Val );
   Show( result, L"Int16", int16Val.ToString() );
   
   // Int32
   result = Int32::TryParse( L"3", NumberStyles::Integer, nullptr,  int32Val );
   Show( result, L"Int32", int32Val.ToString() );
   
   // Int64
   result = Int64::TryParse( L"4", NumberStyles::Integer, nullptr,  int64Val );
   Show( result, L"Int64", int64Val.ToString() );
   
   // Decimal
   result = Decimal::TryParse( L"-5.5", NumberStyles::Number, nullptr,  decimalVal );
   Show( result, L"Decimal", decimalVal.ToString() );
   
   // Single
   result = Single::TryParse( L"6.6", static_cast<NumberStyles>((NumberStyles::Float | NumberStyles::AllowThousands)), nullptr,  singleVal );
   Show( result, L"Single", singleVal.ToString() );
   
   // Double
   result = Double::TryParse( L"-7", static_cast<NumberStyles>(NumberStyles::Float | NumberStyles::AllowThousands), nullptr,  doubleVal );
   Show( result, L"Double", doubleVal.ToString() );
   
   // Use the simple Double.TryParse overload, but specify an invalid value.
   result = Double::TryParse( L"abc",  doubleVal );
   Show( result, L"Double #2", doubleVal.ToString() );
   
   //
   Console::WriteLine( msg4, nl );
   
   // SByte
   result = SByte::TryParse( L"-8", NumberStyles::Integer, nullptr,  sbyteVal );
   Show( result, L"SByte", sbyteVal.ToString() );
   
   // UInt16
   result = UInt16::TryParse( L"9", NumberStyles::Integer, nullptr,  uint16Val );
   Show( result, L"UInt16", uint16Val.ToString() );
   
   // UInt32
   result = UInt32::TryParse( L"10", NumberStyles::Integer, nullptr,  uint32Val );
   Show( result, L"UInt32", uint32Val.ToString() );
   
   // UInt64
   result = UInt64::TryParse( L"11", NumberStyles::Integer, nullptr,  uint64Val );
   Show( result, L"UInt64", uint64Val.ToString() );
}

/*
This example produces the following results:

This example demonstrates overloads of the TryParse method for
several base types, as well as the TryParseExact method for DateTime.

Non-numeric types:

Parse for DateTime #1 = 7/4/2004 12:34:56 PM
Parse for DateTime #2 = 7/4/2004 12:34:56 PM
Parse for DateTime #3 = 7/4/2004 12:34:56 PM
Parse for DateTime #4 = 7/4/2004 12:34:56 PM

Parse for Boolean = True
Parse for Char = A

Numeric types:

Parse for Byte = 1
Parse for Int16 = -2
Parse for Int32 = 3
Parse for Int64 = 4
Parse for Decimal = -5.5
Parse for Single = 6.6
Parse for Double = -7
** Parse for Double #2 failed. Invalid input.

The following types are not CLS-compliant:

Parse for SByte = -8
Parse for UInt16 = 9
Parse for UInt32 = 10
Parse for UInt64 = 11
*/
// This example demonstrates overloads of the TryParse method for
// several base types, and the TryParseExact method for DateTime.

// In most cases, this example uses the most complex overload; that is, the overload 
// with the most parameters for a particular type. If a complex overload specifies 
// null (Nothing in Visual Basic) for the IFormatProvider parameter, formatting 
// information is obtained from the culture associated with the current thread. 
// If a complex overload specifies the style parameter, the parameter value is 
// the default value used by the equivalent simple overload.

using System;
using System.Globalization;

class Sample 
{
    public static void Main() 
    {
    bool     success;
    CultureInfo ci;
    string   nl = Environment.NewLine;
    string   msg1 = 
             "This example demonstrates overloads of the TryParse method for{0}" +
             "several base types, as well as the TryParseExact method for DateTime.{0}";
    string   msg2 = "Non-numeric types:{0}";
    string   msg3 = "{0}Numeric types:{0}";
    string   msg4 = "{0}The following types are not CLS-compliant:{0}";

// Non-numeric types.
    Boolean  booleanVal;
    Char     charVal;
    DateTime datetimeVal;

// Numeric types.
    Byte     byteVal;
    Int16    int16Val;
    Int32    int32Val;
    Int64    int64Val;
    Decimal  decimalVal;
    Single   singleVal;
    Double   doubleVal;

// The following types are not CLS-compliant.
    SByte    sbyteVal;
    UInt16   uint16Val;
    UInt32   uint32Val;
    UInt64   uint64Val;
//
    Console.WriteLine(msg1, nl);

// Non-numeric types:
    Console.WriteLine(msg2, nl);
// DateTime
  // TryParse:
    // Assume current culture is en-US, and dates of the form: MMDDYYYY.
    success = DateTime.TryParse("7/4/2004 12:34:56", out datetimeVal);
    Show(success, "DateTime #1", datetimeVal.ToString());

    // Use fr-FR culture, and dates of the form: DDMMYYYY.
    ci = new CultureInfo("fr-FR");
    success = DateTime.TryParse("4/7/2004 12:34:56", 
             ci, DateTimeStyles.None, out datetimeVal);
    Show(success, "DateTime #2", datetimeVal.ToString());

  // TryParseExact:
    // Use fr-FR culture. The format, "G", is short date and long time.
    success = DateTime.TryParseExact("04/07/2004 12:34:56", "G", 
             ci, DateTimeStyles.None, out datetimeVal);
    Show(success, "DateTime #3", datetimeVal.ToString());

    // Assume en-US culture.
    string[] dateFormats = {"f", "F", "g", "G"};
    success = DateTime.TryParseExact("7/4/2004 12:34:56 PM", 
             dateFormats, null, DateTimeStyles.None, 
             out datetimeVal);
    Show(success, "DateTime #4", datetimeVal.ToString());

    Console.WriteLine();
// Boolean
    success = Boolean.TryParse("true", out booleanVal);
    Show(success, "Boolean", booleanVal.ToString());
// Char
    success = Char.TryParse("A", out charVal);
    Show(success, "Char", charVal.ToString());

// Numeric types:
    Console.WriteLine(msg3, nl);
// Byte
    success = Byte.TryParse("1", NumberStyles.Integer, null, out byteVal);
    Show(success, "Byte", byteVal.ToString());
// Int16
    success = Int16.TryParse("-2", NumberStyles.Integer, null, out int16Val);
    Show(success, "Int16", int16Val.ToString());
// Int32
    success = Int32.TryParse("3", NumberStyles.Integer, null, out int32Val);
    Show(success, "Int32", int32Val.ToString());
// Int64
    success = Int64.TryParse("4", NumberStyles.Integer, null, out int64Val);
    Show(success, "Int64", int64Val.ToString());
// Decimal
    success = Decimal.TryParse("-5.5", NumberStyles.Number, null, out decimalVal);
    Show(success, "Decimal", decimalVal.ToString());
// Single
    success = Single.TryParse("6.6", 
             (NumberStyles.Float | NumberStyles.AllowThousands), 
             null, out singleVal);
    Show(success, "Single", singleVal.ToString());
// Double
    success = Double.TryParse("-7", 
             (NumberStyles.Float | NumberStyles.AllowThousands), 
             null, out doubleVal);
    Show(success, "Double", doubleVal.ToString());

// Use the simple Double.TryParse overload, but specify an invalid value.

    success = Double.TryParse("abc", out doubleVal);
    Show(success, "Double #2", doubleVal.ToString());
//
    Console.WriteLine(msg4, nl);
// SByte
    success = SByte.TryParse("-8", NumberStyles.Integer, null, out sbyteVal);
    Show(success, "SByte", sbyteVal.ToString());
// UInt16
    success = UInt16.TryParse("9", NumberStyles.Integer, null, out uint16Val);
    Show(success, "UInt16", uint16Val.ToString());
// UInt32
    success = UInt32.TryParse("10", NumberStyles.Integer, null, out uint32Val);
    Show(success, "UInt32", uint32Val.ToString());
// UInt64
    success = UInt64.TryParse("11", NumberStyles.Integer, null, out uint64Val);
    Show(success, "UInt64", uint64Val.ToString());
    }

    protected static void Show(bool parseSuccess, string typeName, 
                               string parseValue)
    {
    string msgSuccess = "Parse for {0} = {1}";
    string msgFailure = "** Parse for {0} failed. Invalid input.";
//
    if (parseSuccess == true)
        Console.WriteLine(msgSuccess, typeName, parseValue);
    else
        Console.WriteLine(msgFailure, typeName);
   }
}
/*
This example produces the following results:

This example demonstrates overloads of the TryParse method for
several base types, as well as the TryParseExact method for DateTime.

Non-numeric types:

Parse for DateTime #1 = 7/4/2004 12:34:56 PM
Parse for DateTime #2 = 7/4/2004 12:34:56 PM
Parse for DateTime #3 = 7/4/2004 12:34:56 PM
Parse for DateTime #4 = 7/4/2004 12:34:56 PM

Parse for Boolean = True
Parse for Char = A

Numeric types:

Parse for Byte = 1
Parse for Int16 = -2
Parse for Int32 = 3
Parse for Int64 = 4
Parse for Decimal = -5.5
Parse for Single = 6.6
Parse for Double = -7
** Parse for Double #2 failed. Invalid input.

The following types are not CLS-compliant:

Parse for SByte = -8
Parse for UInt16 = 9
Parse for UInt32 = 10
Parse for UInt64 = 11
*/
' This example demonstrates overloads of the TryParse method for
' several base types, and the TryParseExact method for DateTime.
' In most cases, this example uses the most complex overload; that is, the overload 
' with the most parameters for a particular type. If a complex overload specifies 
' null (Nothing in Visual Basic) for the IFormatProvider parameter, formatting 
' information is obtained from the culture associated with the current thread. 
' If a complex overload specifies the style parameter, the parameter value is 
' the default value used by the equivalent simple overload.

Imports System.Globalization

Class Sample
   Public Shared Sub Main()
      Dim result As Boolean
      Dim ci As CultureInfo
      Dim nl As String = Environment.NewLine
      Dim msg1 As String = _
                 "This example demonstrates overloads of the TryParse method for{0}" & _
                 "several base types, as well as the TryParseExact method for DateTime.{0}"
      Dim msg2 As String = "Non-numeric types:{0}"
      Dim msg3 As String = "{0}Numeric types:{0}"
      Dim msg4 As String = "{0}The following types are not CLS-compliant:{0}"
      
      ' Non-numeric types.
      Dim booleanVal As [Boolean]
      Dim charVal As [Char]
      Dim datetimeVal As DateTime
      
      ' Numeric types.
      Dim byteVal As [Byte]
      Dim int16Val As Int16
      Dim int32Val As Int32
      Dim int64Val As Int64
      Dim decimalVal As [Decimal]
      Dim singleVal As [Single]
      Dim doubleVal As [Double]
      
      ' The following types are not CLS-compliant.
      Dim sbyteVal As SByte
      Dim uint16Val As UInt16
      Dim uint32Val As UInt32
      Dim uint64Val As UInt64
      '
      Console.WriteLine(msg1, nl)
      
      ' Non-numeric types:
      Console.WriteLine(msg2, nl)
      ' DateTime
      ' TryParse:
      ' Assume current culture is en-US, and dates of the form: MMDDYYYY.
      result = DateTime.TryParse("7/4/2004 12:34:56", datetimeVal)
      Show(result, "DateTime #1", datetimeVal.ToString())
      
      ' Use fr-FR culture, and dates of the form: DDMMYYYY.
      ci = New CultureInfo("fr-FR")
      result = DateTime.TryParse("4/7/2004 12:34:56", ci, DateTimeStyles.None, datetimeVal)
      Show(result, "DateTime #2", datetimeVal.ToString())
      
      ' TryParseExact:
      ' Use fr-FR culture. The format, "G", is short date and long time.
      result = DateTime.TryParseExact("04/07/2004 12:34:56", "G", ci, DateTimeStyles.None, datetimeVal)
      Show(result, "DateTime #3", datetimeVal.ToString())
      
      ' Assume en-US culture.
      Dim dateFormats As String() =  {"f", "F", "g", "G"}
      result = DateTime.TryParseExact("7/4/2004 12:34:56 PM", dateFormats, Nothing, DateTimeStyles.None, datetimeVal)
      Show(result, "DateTime #4", datetimeVal.ToString())
      
      Console.WriteLine()
      ' Boolean
      result = [Boolean].TryParse("true", booleanVal)
      Show(result, "Boolean", booleanVal.ToString())
      ' Char
      result = [Char].TryParse("A", charVal)
      Show(result, "Char", charVal.ToString())
      
      ' Numeric types:
      Console.WriteLine(msg3, nl)
      ' Byte
      result = [Byte].TryParse("1", NumberStyles.Integer, Nothing, byteVal)
      Show(result, "Byte", byteVal.ToString())
      ' Int16
      result = Int16.TryParse("-2", NumberStyles.Integer, Nothing, int16Val)
      Show(result, "Int16", int16Val.ToString())
      ' Int32
      result = Int32.TryParse("3", NumberStyles.Integer, Nothing, int32Val)
      Show(result, "Int32", int32Val.ToString())
      ' Int64
      result = Int64.TryParse("4", NumberStyles.Integer, Nothing, int64Val)
      Show(result, "Int64", int64Val.ToString())
      ' Decimal
      result = [Decimal].TryParse("-5.5", NumberStyles.Number, Nothing, decimalVal)
      Show(result, "Decimal", decimalVal.ToString())
      ' Single
      result = [Single].TryParse("6.6", NumberStyles.Float Or NumberStyles.AllowThousands, Nothing, singleVal)
      Show(result, "Single", singleVal.ToString())
      ' Double
      result = [Double].TryParse("-7", NumberStyles.Float Or NumberStyles.AllowThousands, Nothing, doubleVal)
      Show(result, "Double", doubleVal.ToString())
      
      ' Use the simple Double.TryParse overload, but specify an invalid value.
      result = [Double].TryParse("abc", doubleVal)
      Show(result, "Double #2", doubleVal.ToString())
      '
      Console.WriteLine(msg4, nl)
      ' SByte
      result = SByte.TryParse("-8", NumberStyles.Integer, Nothing, sbyteVal)
      Show(result, "SByte", sbyteVal.ToString())
      ' UInt16
      result = UInt16.TryParse("9", NumberStyles.Integer, Nothing, uint16Val)
      Show(result, "UInt16", uint16Val.ToString())
      ' UInt32
      result = UInt32.TryParse("10", NumberStyles.Integer, Nothing, uint32Val)
      Show(result, "UInt32", uint32Val.ToString())
      ' UInt64
      result = UInt64.TryParse("11", NumberStyles.Integer, Nothing, uint64Val)
      Show(result, "UInt64", uint64Val.ToString())
   End Sub
   
   
   Protected Shared Sub Show(parseResult As Boolean, typeName As String, parseValue As String)
      Dim msgSuccess As String = "Parse for {0} = {1}"
      Dim msgFailure As String = "** Parse for {0} failed. Invalid input."
      '
      If parseResult = True Then
         Console.WriteLine(msgSuccess, typeName, parseValue)
      Else
         Console.WriteLine(msgFailure, typeName)
      End If
   End Sub
End Class
'This example produces the following results:
'
'This example demonstrates overloads of the TryParse method for
'several base types, as well as the TryParseExact method for DateTime.
'
'Non-numeric types:
'
'Parse for DateTime #1 = 7/4/2004 12:34:56 PM
'Parse for DateTime #2 = 7/4/2004 12:34:56 PM
'Parse for DateTime #3 = 7/4/2004 12:34:56 PM
'Parse for DateTime #4 = 7/4/2004 12:34:56 PM
'
'Parse for Boolean = True
'Parse for Char = A
'
'Numeric types:
'
'Parse for Byte = 1
'Parse for Int16 = -2
'Parse for Int32 = 3
'Parse for Int64 = 4
'Parse for Decimal = -5.5
'Parse for Single = 6.6
'Parse for Double = -7
'** Parse for Double #2 failed. Invalid input.
'
'The following types are not CLS-compliant:
'
'Parse for SByte = -8
'Parse for UInt16 = 9
'Parse for UInt32 = 10
'Parse for UInt64 = 11
'

Comentarios

El TryParse método es como el Parse método, con la TryParse excepción de que el método no produce una excepción si se produce un error en la conversión.The TryParse method is like the Parse method, except the TryParse method does not throw an exception if the conversion fails.

Se aplica a

Consulte también: