Char.TryParse Method

Parameters

• s
  Type: System.String
  A string containing a single character or nulla null reference (Nothing in Visual Basic).

• result
  Type: System.Char%
  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. The conversion fails if the s parameter is nulla null reference (Nothing in Visual Basic) or the length of s is not 1. This parameter is passed uninitialized.

Return Value

Type: System.Boolean
true if the s parameter was converted successfully; otherwise, false.

' 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 Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim result As Boolean
      Dim ci As CultureInfo
      Dim nl As String = vbCrLf
      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
      '
      outputBlock.Text &= String.Format(msg1, nl) & vbCrLf

      ' Non-numeric types:
      outputBlock.Text &= String.Format(msg2, nl) & vbCrLf
      ' 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(outputBlock, 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(outputBlock, 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(outputBlock, 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(outputBlock, result, "DateTime #4", datetimeVal.ToString())

      outputBlock.Text &= vbCrLf
      ' Boolean
      result = [Boolean].TryParse("true", booleanVal)
      Show(outputBlock, result, "Boolean", booleanVal.ToString())
      ' Char
      result = [Char].TryParse("A", charVal)
      Show(outputBlock, result, "Char", charVal.ToString())

      ' Numeric types:
      outputBlock.Text &= String.Format(msg3, nl) & vbCrLf
      ' Byte
      result = [Byte].TryParse("1", NumberStyles.Integer, Nothing, byteVal)
      Show(outputBlock, result, "Byte", byteVal.ToString())
      ' Int16
      result = Int16.TryParse("-2", NumberStyles.Integer, Nothing, int16Val)
      Show(outputBlock, result, "Int16", int16Val.ToString())
      ' Int32
      result = Int32.TryParse("3", NumberStyles.Integer, Nothing, int32Val)
      Show(outputBlock, result, "Int32", int32Val.ToString())
      ' Int64
      result = Int64.TryParse("4", NumberStyles.Integer, Nothing, int64Val)
      Show(outputBlock, result, "Int64", int64Val.ToString())
      ' Decimal
      result = [Decimal].TryParse("-5.5", NumberStyles.Number, Nothing, decimalVal)
      Show(outputBlock, result, "Decimal", decimalVal.ToString())
      ' Single
      result = [Single].TryParse("6.6", NumberStyles.Float Or NumberStyles.AllowThousands, Nothing, singleVal)
      Show(outputBlock, result, "Single", singleVal.ToString())
      ' Double
      result = [Double].TryParse("-7", NumberStyles.Float Or NumberStyles.AllowThousands, Nothing, doubleVal)
      Show(outputBlock, result, "Double", doubleVal.ToString())

      ' Use the simple Double.TryParse overload, but specify an invalid value.
      result = [Double].TryParse("abc", doubleVal)
      Show(outputBlock, result, "Double #2", doubleVal.ToString())
      '
      outputBlock.Text &= String.Format(msg4, nl) & vbCrLf
      ' SByte
      result = SByte.TryParse("-8", NumberStyles.Integer, Nothing, sbyteVal)
      Show(outputBlock, result, "SByte", sbyteVal.ToString())
      ' UInt16
      result = UInt16.TryParse("9", NumberStyles.Integer, Nothing, uint16Val)
      Show(outputBlock, result, "UInt16", uint16Val.ToString())
      ' UInt32
      result = UInt32.TryParse("10", NumberStyles.Integer, Nothing, uint32Val)
      Show(outputBlock, result, "UInt32", uint32Val.ToString())
      ' UInt64
      result = UInt64.TryParse("11", NumberStyles.Integer, Nothing, uint64Val)
      Show(outputBlock, result, "UInt64", uint64Val.ToString())
   End Sub 'Main


   Protected Shared Sub Show(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal parseResult As Boolean, ByVal typeName As String, ByVal 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
         outputBlock.Text &= String.Format(msgSuccess, typeName, parseValue) & vbCrLf
      Else
         outputBlock.Text &= String.Format(msgFailure, typeName) & vbCrLf
      End If
   End Sub 'Show
End Class 'Sample '
'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 Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      bool result;
      CultureInfo ci;
      string nl = "\n";
      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;
      //
      outputBlock.Text += String.Format(msg1, nl) + "\n";

      // Non-numeric types:
      outputBlock.Text += String.Format(msg2, nl) + "\n";
      // DateTime
      // TryParse:
      // Assume current culture is en-US, and dates of the form: MMDDYYYY.
      result = DateTime.TryParse("7/4/2004 12:34:56", out datetimeVal);
      Show(outputBlock, 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, out datetimeVal);
      Show(outputBlock, 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, out datetimeVal);
      Show(outputBlock, result, "DateTime #3", datetimeVal.ToString());

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

      outputBlock.Text += "\n";
      // Boolean
      result = Boolean.TryParse("true", out booleanVal);
      Show(outputBlock, result, "Boolean", booleanVal.ToString());
      // Char
      result = Char.TryParse("A", out charVal);
      Show(outputBlock, result, "Char", charVal.ToString());

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

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

      result = Double.TryParse("abc", out doubleVal);
      Show(outputBlock, result, "Double #2", doubleVal.ToString());
      //
      outputBlock.Text += String.Format(msg4, nl) + "\n";
      // SByte
      result = SByte.TryParse("-8", NumberStyles.Integer, null, out sbyteVal);
      Show(outputBlock, result, "SByte", sbyteVal.ToString());
      // UInt16
      result = UInt16.TryParse("9", NumberStyles.Integer, null, out uint16Val);
      Show(outputBlock, result, "UInt16", uint16Val.ToString());
      // UInt32
      result = UInt32.TryParse("10", NumberStyles.Integer, null, out uint32Val);
      Show(outputBlock, result, "UInt32", uint32Val.ToString());
      // UInt64
      result = UInt64.TryParse("11", NumberStyles.Integer, null, out uint64Val);
      Show(outputBlock, result, "UInt64", uint64Val.ToString());
   }

   protected static void Show(System.Windows.Controls.TextBlock outputBlock, bool parseResult, string typeName,
                              string parseValue)
   {
      string msgSuccess = "Parse for {0} = {1}";
      string msgFailure = "** Parse for {0} failed. Invalid input.";
      //
      if (parseResult == true)
         outputBlock.Text += String.Format(msgSuccess, typeName, parseValue) + "\n";
      else
         outputBlock.Text += String.Format(msgFailure, typeName) + "\n";
   }
}
/*
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
*/