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Byte.TryParse Method (String, NumberStyles, IFormatProvider, Byte%)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Converts the string representation of a number in a specified style and culture-specific format to its Byte equivalent. A return value indicates whether the conversion succeeded or failed.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Shared Function TryParse ( _
    s As String, _
    style As NumberStyles, _
    provider As IFormatProvider, _
    <OutAttribute> ByRef result As Byte _
) As Boolean

public static bool TryParse(
    string s,
    NumberStyles style,
    IFormatProvider provider,
    out byte result
)

Parameters

  • s
    Type: System.String
    A string containing a number to convert. The string is interpreted using the style specified by style.
  • provider
    Type: System.IFormatProvider
    An IFormatProvider object that supplies culture-specific formatting information about s. If provider is nulla null reference (Nothing in Visual Basic), the thread current culture is used.
  • result
    Type: System.Byte%
    When this method returns, contains the 8-bit unsigned integer value equivalent to the number contained in s if the conversion succeeded, or zero if the conversion failed. The conversion fails if the s parameter is nulla null reference (Nothing in Visual Basic), is not of the correct format, or represents a number less than MinValue or greater than MaxValue. This parameter is passed uninitialized.

Return Value

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

Exceptions

Exception Condition
ArgumentException

style is not a NumberStyles value.

-or-

style is not a combination of NumberStyles.AllowHexSpecifier and NumberStyles.HexNumber values.

Remarks

The TryParse method is like the Parse method, except the TryParse method does not throw an exception if the conversion fails.

The s parameter is parsed using the formatting information in a NumberFormatInfo object supplied by the provider parameter.

The style parameter defines the style elements (such as white space or the positive sign) that are allowed in the s parameter for the parse operation to succeed. It must be a combination of bit flags from the NumberStyles enumeration. Depending on the value of style, the s parameter may include the following elements:

[ws][$][sign]digits[.fractional_digits][e[sign]digits][ws]

Or, if the style parameter includes AllowHexSpecifier:

[ws]hexdigits[ws]

Elements in square brackets ( [ and ] ) are optional. The following table describes each element.

Element

Description

ws

Optional white space. White space can appear at the beginning of s if style includes the NumberStyles.AllowLeadingWhite flag, or at the end of s if style includes the NumberStyles.AllowTrailingWhite flag.

$

A culture-specific currency symbol. Its position in the string is defined by the NumberFormatInfo.CurrencyPositivePattern property of the NumberFormatInfo object returned by the GetFormat method of the provider parameter. The currency symbol can appear in s if style includes the NumberStyles.AllowCurrencySymbol flag.

sign

An optional positive sign. (The parse operation fails if a negative sign is present in s.) The sign can appear at the beginning of s if style includes the NumberStyles.AllowLeadingSign flag, or at the end of s if style includes the NumberStyles.AllowTrailingSign flag.

digits

A sequence of digits from 0 through 9.

.

A culture-specific decimal point symbol. The decimal point symbol of the culture specified by provider can appear in s if style includes the NumberStyles.AllowDecimalPoint flag.

fractional_digits

One or more occurrences of the digit 0. Fractional digits can appear in s only if style includes the NumberStyles.AllowDecimalPoint flag.

e

The e or E character, which indicates that the value is represented in exponential notation. The s parameter can represent a number in exponential notation if style includes the NumberStyles.AllowExponent flag.

hexdigits

A sequence of hexadecimal digits from 0 through f, or 0 through F.

A string with decimal digits only (which corresponds to the NumberStyles.None style) always parses successfully. Most of the remaining NumberStyles members control elements that may be but are not required to be present in this input string. The following table indicates how individual NumberStyles members affect the elements that may be present in s.

Non-composite NumberStyles values

Elements permitted in s in addition to digits

NumberStyles.None

Decimal digits only.

NumberStyles.AllowDecimalPoint

The . and fractional_digits elements. However, fractional_digits must consist of only one or more 0 digits or the method returns false.

NumberStyles.AllowExponent

The s parameter can also use exponential notation. If s represents a number in exponential notation, it must represent an integer within the range of the Byte data type without a non-zero fractional component.

NumberStyles.AllowLeadingWhite

The ws element at the beginning of s.

NumberStyles.AllowTrailingWhite

The ws element at the end of s.

NumberStyles.AllowLeadingSign

A positive sign can appear before digits.

NumberStyles.AllowTrailingSign

A positive sign can appear after digits.

NumberStyles.AllowParentheses

Although this flag is supported, the method returns false if parentheses are present in s.

NumberStyles.AllowThousands

Although the group separator symbol can appear in s, it can be preceded by only one or more 0 digits.

NumberStyles.AllowCurrencySymbol

The $ element.

If the NumberStyles.AllowHexSpecifier flag is used, s must be a hexadecimal value. The only other flags that can be present in style are NumberStyles.AllowLeadingWhite and NumberStyles.AllowTrailingWhite. (The NumberStyles enumeration has a composite number style, NumberStyles.HexNumber, that includes both white space flags.)

The provider parameter is an IFormatProvider implementation, such as a CultureInfo object or a NumberFormatInfo object, whose GetFormat method returns a NumberFormatInfo object. The NumberFormatInfo object provides culture-specific information about the format of s.

Examples

The following example calls the TryParse(String, NumberStyles, IFormatProvider, Byte%) method with a number of different string values.

Imports System.Globalization

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim byteString As String
      Dim styles As NumberStyles

      byteString = "1024"
      styles = NumberStyles.Integer
      CallTryParse(outputBlock, byteString, styles)

      byteString = "100.1"
      styles = NumberStyles.Integer Or NumberStyles.AllowDecimalPoint
      CallTryParse(outputBlock, byteString, styles)

      byteString = "100.0"
      CallTryParse(outputBlock, byteString, styles)

      byteString = "+100"
      styles = NumberStyles.Integer Or NumberStyles.AllowLeadingSign _
               Or NumberStyles.AllowTrailingSign
      CallTryParse(outputBlock, byteString, styles)

      byteString = "-100"
      CallTryParse(outputBlock, byteString, styles)

      byteString = "000000000000000100"
      CallTryParse(outputBlock, byteString, styles)

      byteString = "00,100"
      styles = NumberStyles.Integer Or NumberStyles.AllowThousands
      CallTryParse(outputBlock, byteString, styles)

      byteString = "2E+3   "
      styles = NumberStyles.Integer Or NumberStyles.AllowExponent
      CallTryParse(outputBlock, byteString, styles)

      byteString = "FF"
      styles = NumberStyles.HexNumber
      CallTryParse(outputBlock, byteString, styles)

      byteString = "0x1F"
      CallTryParse(outputBlock, byteString, styles)
   End Sub

   Private Sub CallTryParse(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal stringToConvert As String, ByVal styles As NumberStyles)
      Dim byteValue As Byte
      Dim result As Boolean = Byte.TryParse(stringToConvert, styles, Nothing, _
                                            byteValue)
      If result Then
         outputBlock.Text += String.Format("Converted '{0}' to {1}", _
                        stringToConvert, byteValue) + vbCrLf
      Else
         If stringToConvert Is Nothing Then stringToConvert = ""
         outputBlock.Text += String.Format("Attempted conversion of '{0}' failed.", _
                           stringToConvert.ToString()) + vbCrLf
      End If
   End Sub
End Module
' The example displays the following output:
'       Attempted conversion of '1024' failed.
'       Attempted conversion of '100.1' failed.
'       Converted '100.0' to 100
'       Converted '+100' to 100
'       Attempted conversion of '-100' failed.
'       Converted '000000000000000100' to 100
'       Converted '00,100' to 100
'       Attempted conversion of '2E+3   ' failed.
'       Converted 'FF' to 255
'       Attempted conversion of '0x1F' failed.

using System;
using System.Globalization;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      string byteString;
      NumberStyles styles;

      byteString = "1024";
      styles = NumberStyles.Integer;
      CallTryParse(outputBlock, byteString, styles);

      byteString = "100.1";
      styles = NumberStyles.Integer | NumberStyles.AllowDecimalPoint;
      CallTryParse(outputBlock, byteString, styles);

      byteString = "100.0";
      CallTryParse(outputBlock, byteString, styles);

      byteString = "+100";
      styles = NumberStyles.Integer | NumberStyles.AllowLeadingSign
               | NumberStyles.AllowTrailingSign;
      CallTryParse(outputBlock, byteString, styles);

      byteString = "-100";
      CallTryParse(outputBlock, byteString, styles);

      byteString = "000000000000000100";
      CallTryParse(outputBlock, byteString, styles);

      byteString = "00,100";
      styles = NumberStyles.Integer | NumberStyles.AllowThousands;
      CallTryParse(outputBlock, byteString, styles);

      byteString = "2E+3   ";
      styles = NumberStyles.Integer | NumberStyles.AllowExponent;
      CallTryParse(outputBlock, byteString, styles);

      byteString = "FF";
      styles = NumberStyles.HexNumber;
      CallTryParse(outputBlock, byteString, styles);

      byteString = "0x1F";
      CallTryParse(outputBlock, byteString, styles);
   }

   private static void CallTryParse(System.Windows.Controls.TextBlock outputBlock, string stringToConvert, NumberStyles styles)
   {
      Byte byteValue;
      bool result = Byte.TryParse(stringToConvert, styles,
                                  null as IFormatProvider, out byteValue);
      if (result)
         outputBlock.Text += String.Format("Converted '{0}' to {1}",
                        stringToConvert, byteValue) + "\n";
      else
         outputBlock.Text += String.Format("Attempted conversion of '{0}' failed.",
                           stringToConvert.ToString()) + "\n";
   }
}
// The example displays the following output:
//       Attempted conversion of '1024' failed.
//       Attempted conversion of '100.1' failed.
//       Converted '100.0' to 100
//       Converted '+100' to 100
//       Attempted conversion of '-100' failed.
//       Converted '000000000000000100' to 100
//       Converted '00,100' to 100
//       Attempted conversion of '2E+3   ' failed.
//       Converted 'FF' to 255
//       Attempted conversion of '0x1F' failed.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.