Char.TryParse(String, Char) Metodo

  • Riferimento

Definizione

Spazio dei nomi:
System
Assembly:
System.Runtime.dll
Assembly:
netstandard.dll
Assembly:
mscorlib.dll

Converte il valore della stringa specificata nell'equivalente carattere Unicode. Un codice restituito indica se la conversione ha avuto esito positivo o negativo.

public:
 static bool TryParse(System::String ^ s, [Runtime::InteropServices::Out] char % result);
public static bool TryParse (string s, 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

Parametri

s
String

Stringa che contiene un solo carattere oppure null.

result
Char

Se la conversione ha esito positivo, il risultato restituito dal metodo contiene un carattere Unicode equivalente all'unico carattere contenuto nel parametro s; in caso contrario, il risultato contiene un valore non definito. La conversione non viene eseguita se il parametro s è null o se la lunghezza di s non è 1. Questo parametro viene passato non inizializzato.

Restituisce

Boolean

true se il parametro s è stato convertito correttamente; in caso contrario, false.

Esempio

Nell'esempio di codice seguente vengono illustrati gli overload del metodo per diversi tipi TryParse di base e il metodo per il tipo di TryParseExact DateTime base.

// 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.

open System
open System.Globalization

let show parseSuccess typeName parseValue =
    if parseSuccess then
        printfn $"Parse for %s{typeName} = %s{parseValue}"
    else
        printfn $"** Parse for %s{typeName} failed. Invalid input."

[<EntryPoint>]
let main _ =
    printfn "This example demonstrates overloads of the TryParse method for\nseveral base types, as well as the TryParseExact method for DateTime.\n"

// Non-numeric types:
    printfn "Non-numeric types:\n"
// DateTime
  // TryParse:
    // Assume current culture is en-US, and dates of the form: MMDDYYYY.
    let success, datetimeVal = DateTime.TryParse "7/4/2004 12:34:56"
    show success "DateTime #1" (string datetimeVal)

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

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

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

    printfn ""
// Boolean
    let success, booleanVal = Boolean.TryParse "true"
    show success "Boolean" (string booleanVal)
// Char
    let success, charVal = Char.TryParse "A"
    show success "Char" (string charVal)

// Numeric types:
    printfn "\nNumeric types:\n"
// Byte
    let success, byteVal = Byte.TryParse("1", NumberStyles.Integer, null)
    show success "Byte" (string byteVal)
// Int16
    let success, int16Val = Int16.TryParse("-2", NumberStyles.Integer, null)
    show success "Int16" (string int16Val)
// Int32
    let success, int32Val = Int32.TryParse("3", NumberStyles.Integer, null)
    show success "Int32" (string int32Val)
// Int64
    let success, int64Val = Int64.TryParse("4", NumberStyles.Integer, null)
    show success "Int64" (string int64Val)
// Decimal
    let success, decimalVal = Decimal.TryParse("-5.5", NumberStyles.Number, null)
    show success "Decimal" (string decimalVal)
// Single
    let success, singleVal = Single.TryParse("6.6", NumberStyles.Float ||| NumberStyles.AllowThousands, null)
    show success "Single" (string singleVal)
// Double
    let success, doubleVal = Double.TryParse("-7", NumberStyles.Float ||| NumberStyles.AllowThousands, null)
    show success "Double" (string doubleVal)

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

    let success, doubleVal = Double.TryParse "abc"
    show success "Double #2" (string doubleVal)
//
    printfn "\nThe following types are not CLS-compliant:\n"
// SByte
    let success, sbyteVal = SByte.TryParse("-8", NumberStyles.Integer, null)
    show success "SByte" (string sbyteVal)
// UInt16
    let success, uint16Val = UInt16.TryParse("9", NumberStyles.Integer, null)
    show success "UInt16" (string uint16Val)
// UInt32
    let success, uint32Val = UInt32.TryParse("10", NumberStyles.Integer, null)
    show success "UInt32" (string uint32Val)
// UInt64
    let success, uint64Val = UInt64.TryParse("11", NumberStyles.Integer, null)
    show success "UInt64" (string uint64Val)

    0

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

Commenti

Il metodo è simile al metodo , ad eccezione del fatto che il metodo non TryParse genera un'eccezione se la Parse TryParse conversione ha esito negativo.

Si applica a

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