Byte.TryParse Method (System) (original) (raw)

Source:

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.

public:
 static bool TryParse(System::String ^ s, System::Globalization::NumberStyles style, IFormatProvider ^ provider, [Runtime::InteropServices::Out] System::Byte % result);

public:
 static bool TryParse(System::String ^ s, System::Globalization::NumberStyles style, IFormatProvider ^ provider, [Runtime::InteropServices::Out] System::Byte % result) = System::Numerics::INumberBase<System::Byte>::TryParse;

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

public static bool TryParse(string? s, System.Globalization.NumberStyles style, IFormatProvider? provider, out byte result);

static member TryParse : string * System.Globalization.NumberStyles * IFormatProvider * byte -> bool

Public Shared Function TryParse (s As String, style As NumberStyles, provider As IFormatProvider, ByRef result As Byte) As Boolean

Parameters

String

A string containing a number to convert. The string is interpreted using the style specified by style.

style

NumberStyles

A bitwise combination of enumeration values that indicates the style elements that can be present in s. A typical value to specify is Integer.

provider

IFormatProvider

An object that supplies culture-specific formatting information about s. If provider is null, the thread current culture is used.

result

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 null or Empty, is not of the correct format, or represents a number less than Byte.MinValue or greater than Byte.MaxValue. This parameter is passed uninitialized; any value originally supplied in result will be overwritten.

Returns

true if s was converted successfully; otherwise, false.

Exceptions

Examples

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

using System;
using System.Globalization;

public class ByteConversion2
{
   public static void Main()
   {
      string byteString;
      NumberStyles styles;

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

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

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

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

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

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

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

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

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

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

   private static void CallTryParse(string stringToConvert, NumberStyles styles)
   {
      Byte byteValue;
      bool result = Byte.TryParse(stringToConvert, styles,
                                  null as IFormatProvider, out byteValue);
      if (result)
         Console.WriteLine("Converted '{0}' to {1}",
                        stringToConvert, byteValue);
      else
         Console.WriteLine("Attempted conversion of '{0}' failed.",
                           stringToConvert.ToString());
   }
}
// The example displays the following output to the console:
//       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.

open System
open System.Globalization

let callTryParse (stringToConvert: string) (styles: NumberStyles) =
    match Byte.TryParse(stringToConvert, styles, null) with
    | true, byteValue ->
        printfn $"Converted '{stringToConvert}' to {byteValue}"
    | _ ->
        printfn $"Attempted conversion of '{stringToConvert}' failed."
                        
[<EntryPoint>]
let main _ =
    let byteString = "1024"
    let styles = NumberStyles.Integer
    callTryParse byteString styles

    let byteString = "100.1"
    let styles = NumberStyles.Integer ||| NumberStyles.AllowDecimalPoint
    callTryParse byteString styles

    let byteString = "100.0"
    callTryParse byteString styles

    let byteString = "+100"
    let styles = NumberStyles.Integer ||| NumberStyles.AllowLeadingSign ||| NumberStyles.AllowTrailingSign
    callTryParse byteString styles

    let byteString = "-100"
    callTryParse byteString styles

    let byteString = "000000000000000100"
    callTryParse byteString styles

    let byteString = "00,100"
    let styles = NumberStyles.Integer ||| NumberStyles.AllowThousands
    callTryParse byteString styles

    let byteString = "2E+3   "
    let styles = NumberStyles.Integer ||| NumberStyles.AllowExponent
    callTryParse byteString styles

    let byteString = "FF"
    let styles = NumberStyles.HexNumber
    callTryParse byteString styles

    let byteString = "0x1F"
    callTryParse byteString styles

    0

// The example displays the following output to the console:
//       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.

Imports System.Globalization

Module ByteConversion2
   Public Sub Main()
      Dim byteString As String 
      Dim styles As NumberStyles
      
      byteString = "1024"
      styles = NumberStyles.Integer
      CallTryParse(byteString, styles)
      
      byteString = "100.1"
      styles = NumberStyles.Integer Or NumberStyles.AllowDecimalPoint
      CallTryParse(byteString, styles)
      
      byteString = "100.0"
      CallTryParse(byteString, styles)
      
      byteString = "+100"
      styles = NumberStyles.Integer Or NumberStyles.AllowLeadingSign _
               Or NumberStyles.AllowTrailingSign
      CallTryParse(byteString, styles)
      
      byteString = "-100"
      CallTryParse(byteString, styles)
      
      byteString = "000000000000000100"
      CallTryParse(byteString, styles)
      
      byteString = "00,100"      
      styles = NumberStyles.Integer Or NumberStyles.AllowThousands
      CallTryParse(byteString, styles)
      
      byteString = "2E+3   "
      styles = NumberStyles.Integer Or NumberStyles.AllowExponent
      CallTryParse(byteString, styles)
      
      byteString = "FF"
      styles = NumberStyles.HexNumber
      CallTryParse(byteString, styles)
      
      byteString = "0x1F"
      CallTryParse(byteString, styles)
   End Sub
   
   Private Sub CallTryParse(stringToConvert As String, styles As NumberStyles)  
      Dim byteValue As Byte
      Dim result As Boolean = Byte.TryParse(stringToConvert, styles, Nothing, _
                                            byteValue)
      If result Then
         Console.WriteLine("Converted '{0}' to {1}", _
                        stringToConvert, byteValue)
      Else
         If stringToConvert Is Nothing Then stringToConvert = ""
         Console.WriteLine("Attempted conversion of '{0}' failed.", _
                           stringToConvert.ToString())
      End If                        
   End Sub
End Module
' The example displays the following output to the console:
'       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.

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.

Note

Any terminating NUL (U+0000) characters in s are ignored by the parsing operation, regardless of the value of the style argument.

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 without a prefix. For example, "F3" parses successfully, but "0xF3" does not. 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.